STRESS-STRAIN-STRENGTH ANISOTROPY OF VARVED CLAYS by Surachat Sambhandharaksa BE, University of New South Wales (1967) ME, Asian Institute of Technology (1970) SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF SCIENCE at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY August 1977 -1 j2 .UJ-. Signature of Author ._ _ Department of Civil Engineering Certified by Thesis Supervisor Accepted by I I I~ I IIII C~an,'nt II I Committee on Graduate Studies Archives JAN 5 1978 STRESS-STRAIN-STRENGTH ANISCMT PY OF VARVED CLAYS by Surachat Sambhandharaksa Submitted to the Department of Civil Engineering on August, 1977 in partial fulfillment of the requirements for the Degree of Doctor of Science. ABSTRACT The objectives of this thesis are: (1) to contribute to a fundamental understanding of the nature of undrained shear strength anisotropy of varved clays; (2) to present best estimates of normalized stress-strain-strength parameters for undrained total stress analyses and for predictions of pore pressures and undrained deformations used in the design of structures on Connecticut Valley varved clays, with background information showing how these parameters were developed; and (3) to recommend suitable testing procedures for developing normalized soil parameters for other varved clay deposits. To achieve these objectives, several types of K o consolidated and isotropically consolidated strength tests were performed at various overconsolidation ratios (OCR). These include: (1) SHANSEP CIUC tests on Amherst and East Windsor samples with different inclinations; (2) SHANSEP CK UC and CKoUE tests on vertical Amherst and East Windsor samples; (3) SHANSEP CKoUDSS tests on vertical Northampton, Amherst, and East Windsor samples; and (4) SHANSEP CIUE tests on vertical and horizontal East Windsor samples. The testing program also includes CKoU plane strain tests on normally consolidated Northampton samples and CKoUDSS tests on normally consolidated inclined East Windsor samples. For the study of suitable testing procedures of varved clay, RECOMPRESSION CKoU triaxial compression and extension tests at OCR's of 2 and 4, and RECOMPRESSION CIUC tests on East Windsor samples with different inclinations at OCR=4 (the in situ OCR) were performed along with UUC tests on East Windsor samples with different inclinations. The three factors that control the anisotropic strength behavior of varved clays are: (1) the layered nature of the soil (material anisotropy); (2) the prior Ko consolidation (structural anisotropy); and (3) when Kofl, the stress system induced anisotropy. An attempt was made to separate the influence on undrained shear strength (qf) of material anisotropy from the effects due to structural and stress system induced anisotropy. The anisotropy in qf/avm is due to the anisotropy in pore pressure response and in the normalized effective stress envelope (NESE) at qf, the plot of qfium versus pvm. A major finding is the fact the anisotropy in NESE at (/ _ is onlydue to material anisotropy. Thus, there are three possible NESE at (/C3)max, ii namely: NESE for failure across the varves, that for failure within a clay layer, and that for failure within a silt layer. The first two NESE are shown to be basic material properties. Test data on a block sample from East Windsor show that disturbance is mostly due to separation of the varves and is therefore directional dependent. With block samples, the SHANSEP method of consolidation is thought to yield reasonable estimates of undrained shear strength but the stress-strain characteristics are less brittle and less sensitive compared to the in situ soil. Chapter 8 presents: recommended normalized soil parameters for the design of structures on Connecticut Valley varved clays; type of tests for checking these parameters; recommended testing procedures for developing design strengths for other varved clay deposits; and suitable methods of stability analysis wherein anisotropic strengths are taken into consideration. Thesis Supervisor Title Charles C. Ladd Professor of Civil Engineering iii ACKNOWLEDGEMENTS During the preparation of this thesis, I have received help and encouragement from many people and organizations. Their mention here cannot begin to express my sincere thanks for their support. Foremost among these is Professor Charles C. Ladd who is my faculty and thesis advisor. His guidance in the preparation of this thesis, his understanding of my writing problems, the encouragement that he provided in the difficult periods are sincerely appreciated. The Massachusetts Department of Public Works and US Department of Transportation provided financial support during the first two years of this research. Professor R.P. Long of the University of Connecticut provided two block samples of varved clay from East Windsor. I greatly appreciated the long hours Mr. Jacques N. Levadoux spent with me in the laboratory. I also would like to thank former MIT students who contributed valuable test data presented in this thesis. They are David, H. Connell, Suzanne M. Lacasse and Francis D. Leathers. To my thesis committee, Professor T.W. Lambe and Professor Mohsen M. Baligh, I owe a special debt of thanks for their suggestions to improve the quality of this thesis. Special thanks are also extended to Dr. W.A. Marr who kindly reviewed iv this thesis. The thesis was typed by Michele P. Jarrabet and the figures were drafted by Nancy Iffland. V TABLE OF CONTENTS Page TITLE PAGE. ABSTRACT . . . i . . . . . . . ACKNOWLEDGEMENTS. . . . . . . . .. OF TABLES. 2 2.1 2.2 2.2.3 2.3 .. ............. 1 . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . .. . . . . . . . . . . . . 6 6 6 Anisotropy in Undrained Shear Strength . . Measurement of Undrained Shear Strength 6 Anisotropy 9 .. . . . . . The Normalized Soil Properties (NSP) . . . . . . . . . . . . . . . . . . . 13 17 18 18 of Anisotropic Behavior . . . 19 2.3.1 Analytical Approach . 2.3.1(a) Curve Fitting Method 2.3.1(b) . . Theoretical Prediction 2.3.1(c) Factors Affecting the Anisotropic Shear Strength Behavior of Varved Clay Experimental Approach . . . . . . O .. 2.3.2(a) Evidence from UUC Tests . . . 2.3.2(b) Evidence from CIUC Tests . . 2.3.2(c) Evidence from CK Tests . . C~~re,,,,, ,~ r,-3 0,· Z.J.J ummarUy anaL ;olCUsln . . . . . . . . . 2.3.4 Effect of Certain Stress System Variables on Undrained Shear Strength Behavior. . . 2.3.4(a) Effect of Intermediate Principal 2.3.4(b) 3 1 2 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Concept . . Literature Review . 2.3.2 x xiv ................... Introduction Background. 2.2.1 2.2.2 vi ........... Background Objectives Scope . BACKGROUND iv . . . . . . . . . . . . . . . . . . . . . . INTRODUCTION 1.1 1.2 1.3 ii ............... LIST OF FIGURES .... 1 .. ................... TABLE OF CONTENTS. LIST .. . Stress . . . . . . . Effect of K o Consolidation EXPERIMENTALPROGRAM .... . . 21 23 23 25 29 32 34 35 36 60 vi Page ... . . . . . . . .. General Scope and Objectives . ... . . . . . . . . . . . Program Experimental Description of Varved Clays . . . . . . . . . . . Varved Clay . . . . . . . . . 3.3.1 East Windsor Amherst Varved Clay . . . . . . . . . . . . 3.3.2 Clay . . . . . . . . . Varved 3.3.3 Northampton 3.3.4 Hackensack Valley Varved Clay . . . . . . . of Soil Properties . . . . . . . . . . . . Summary . . . . . . . . . . . . Procedures General Testing 60 3.5.1 3.5.2 Consolidated Undrained Triaxial Tests . Testing Problems with Consolidated 73 3.5.3 3.5.4 . . . .. Tests. Triaxial Undrained . . . . . . . The Direct Simple Shear Test The Plane Strain Tests . ... . . . . . . 77 78 79 3.1 3.2 3.3 3.4 3.5 4 60 64 66 67 68 70 71 72 COMPARISON OF NORMALIZED BEHAVIOR OF DIFFERENT VARVED CLAYS . . . . . . . . . . . . . . . . . . . . . and Background. . . 100 . . . . . . . .. 4.1 Introduction 4.2 Effect of Sample Stress History (MPPR) . 4.3 Effect of Soil 4.3.1 4.3.2 Results from CIU Tests. . ..... Results from CKoU Tests 4.3.2(a) Data from CKoUC Tests . . . . .. Location 100 ... . 102 . . . . . . . . . . . . . 105 .... .. 105 107 107 4.3.2(b) Data from CKUDSS Tests . . . . . 108 Data from CKoUE Tests . . . . .. 4.3.2(c) 4.4 4.5 5. 109 Discussion . . . . . . . . . . . . . . .. . . . . . . . . . . Summary and Conclusions . 111 115 EFFECT OF STRESS SYSTEM ON UNDRAINED BEHAVIOR FROM * - . 145 . Introduction . Effect of K o Versus Isotropic Consolidation. .... 145 148 SHANSEP 5.1 5.2 SAMPLES of . . . . . . 148 Method 5.2.2 Volume Change Data from CIU and CKoU 149 ................... 5.2.3 5.2.4 Results from CIUC and CKoUC Tests . . ... Results from CIUE and CKoUE Tests . . . . . 5.2.5 Summary and Discussion. . . . . .. .. .. . . . Effect of Intermediate Principal Stress . . . . . 5.3.1 Method 5.3.2 5.3.3 . .. .161 Results from CIU Tests Results from K Consolidated Plane of Strain 5.3.4 Investigation and Triaxial .. Tests . . . . . . . . . 157 160 . 160 . . . . . . 165 DSS Tests. . ... 5.3.5 Summary and Discussion.. Effect of Testing Method for Shearing Parallel to Varves 5.4.1 I50 154 Interpretation and Results from Special 5.4 . . Investigation . 5.2.1 Tests 5.3 . . . . .. . . . .. . . . . Introduction and Method of Investigation vii 170 181 182 182 Page 5.4.2 5.4.3 Results from CDDS and CIUC Tests Results from CKoUDSS Tests and Their 5.4.4 Interpretation . .. . . . . .. . 184 . * 186 Comparison of Results from CIUC (8=450)and CKoUDSSTests. . . . . . ... 6 5.5 General Discussion ........ 5.6 Summary and CONSIDERATION OF 6.1 6.1.5 . . . . . . . . . .... DISTURBANCE . . . . . 191 . . . . . 251 Experimental Program . . . . . . . ... 256 Effect of Methods for Minimizing Disturbance on Undrained Shear Strength Behavior . . . ... 6.2.1 Behavior from Vertical Loading. . . . . .. 6.2.2 Behavior from Horizontal Loading. ..... 6.2.3 Behavior from Inclined Loading. .. .. . 6.3 6.4 256 257 260 262 Discussion . . . . . . . . . . . . . . . . . . . . 263 Summary and Conclusions. . . . . . . . . . . . . . 266 INTERPRETATION OF ANISOTROPIC BEHAVIOR OF CONNECTICUT VALLEY 8 SAMPLE 188 .190 Introduction and Background .251 6.1.1 Purpose . ....... 251 6.1.2 Types and Causes of Sample Disturbance . 251 6.1.3 General Effect of Sample Disturbance . . . 252 6.1.4 Methods for Minimizing Sample Disturbance 6.2 7 Conclusions. . .. VARVED CLAYS . . . . . . . . . . . . . . . . . . 292 7.1 7.2 Introduction . . . . . . . . . . . . .292 Method of Investigation . . . . . . . . . . ... 294 7.3 7.4 7.5 Interpretation of "Material" Anisotropic Behavior Effect of Structural Aniostropy Component . . .. Interpretation of Combined Anisotropy ...... 296 299 301 7.6 Summary 305 and Conclusions . . . . . . . . . . . . . EVALUATION OF UNDRAINED STRESS-STRAIN-STRENGTH PROPERITES OF CVVC FOR USE IN DESIGN 8.1 Objectives and Scope .... 8.2 . . . . . . . . . . . .... . 322 322 Development of Undrained Strength Parameters of CVVC for Total Stress Stability Analyses Using SHANSEP. . .323 . 8.2.1 Criteria for Developing Design Undrained 8.2.2 Anisotropic Su Parameters Developed by Strength Ladd 8.3 . . Parameter (1975) . . . . . . . . . . . 324 . . . . . .327 8.2.3 Design Parameters Developed by the Author Comparison of the Use of SHANSEP Anisotropic Su Versus Corrected FV Strength Data . . . . 8.3.1 Introduction 8.3.2 Recommended Correction Factor () for Connecticut Valley Varved Clay. .... 331 . . . . . . . . . . . . . . . 331 viii 332 Page 8.3.3 Compatibility of Using SHANSEP Anisotropic Su with M-P Analyses . . . . . 334 Evaluation of Undrained Shear Strength for 8.4 Total Stress Analyses in Practice . . . . . .. 335 8.4.1 8.5 Initial Undrained Shear Strength for Total Stress Analyses (Undrained Case) . 8.4.2 Undrained Shear Strength for Total Stress Analysis in Partially Drained Case . . .. Recommended Parameters for Undrained Analyses of Pore Pressure and Deformation. .339 8.5.1 Parameters for Predictions Using Elastic 8.5.2 .. . . . . . . . . . 339 . . . . . . . . . . . . . . . . . . 343 Recommended Procedures for Checking CVVC NSP and For Developing Normalized Shear Strength Parameters for Other Varved Clays . . . . . .. 8.6.1 Parameters . . . . . . . . . . . . . . . . 346 Recommended Laboratory Testing Procedures for Developing Normalized Soil Parameters for Other Varved Clay Deposits. 10 SUMMARY AND APPENDIX . . . . CONCLUSIONS REFERENCES BIBLIOGRAPHY 345 Recommended Method for Checking Soil 8.6.2 9 336 Parameters for Finite Element Program FEECON 8.6 Theory 335 .. . . .. .... 346 . . . . . . . . . . . . . . . 369 . . . . . . . . . . . . . . 381 . . . . . . . . . . . . . . . . . . . . . . . 387 A - NOTATION . . . . . . . . . . . . . . . . . . . 388 APPENDIX B - BEST ESTIMATE OF STRESS-STRAIN-STRENGTH DATA OF CONNECTICUT VALLEY VARVED CLAYS. . . . 395 APPENDIX C - SUMMARY OF TEST RESULTS FROM CONNECTICUT,VALLEY AND'HACHENSACK VALLEY VAVARVED CLAYS .406 APPENDIX D - TABULATION OF TEST RESULTS FROM AMHERST AND EAST WINDSOR VARVED ix CLAYS . . . . . . . . . . 431 LIST OF TABLES Table No. 2.1 2.2 2.3 2.4 Page General Problems with Testing Methods for Investigating Direction Variation of Undrained Shear Strength (Su ) 38 Prediction of Anisotropy in S from Hansen and Gibson's Equation for Plane Srain Loading 39 Influence of Inherent Anisotropy on Measured Undrained Shear Strengths of Homogeneous Clay from UUC Tests 40 Influence of Inherent Aniostropy on Measured Undrained Shear Strength of Non-Homogeneous Clay from UUC Tests 41 2.5 Anisotropy in Su Measured from CKoUPSC, CKoUDSS, CPSE Tests (Option 4) of Several NC Cohesive Soils 42 2.6 Anisotropy in Su Measured from CK-UC, CK UE, and CKOUDSS Tests (Option 3) of Several Soft Clays 43 Summary of Anisotropic Data from Several NC Cohesive Soils 44 2.7 2.8 Effect of Stress History on Anisotropic Shear Strength Behavior of Boston Blue Clay Measured from Plane Strain Compression and Extension Tests 45 Effect of 2 on Vertical and Horizontal Undrained Shear Strength Behavior of Several NC Cohesive Soils 46 3.1 Summary of the Experimental Program 83 3.2 Summary of Index Properties and Engineering Properties of East Windsor Varved Clay 85 Laboratory Testing Program of East Windsor Varved Clay 86 Laboratory of Testing Program of Amherst Varved Clay 87 Laboratory Testing Program of Northampton Varved Clay 88 2.9 3.3 3.4 3.5 x Table No. 3.6 3.7 3.8 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 5.1 5.2 5.3 5.4 5.5 Page Laboratory Testing Program of Hackensack Valley Varved Clay 89 Summary of the Index Properties of Varved Clay Samples from Amherst, East Windsor, Northampton and Hackensack Valley 90 Comparison of the Undrained Shear Strengths frnmthe CKoUE Tests from Different Testing Procedures 91 Experimental Program for Investigating the Effects of Soil Samples' Stress History and Soil Location on NSP 118 Effect of Sample Stress History on the NSP of Amherst Varved Clay 119 Effect of Stress History on the NSP of Northampton Varved Clay 120 Effect of Sample Stress History on the NSP of East Windsor and Hackensack Valley Varved Clay 121 Effect of Soil Location on NSP from CIUC Tests on Normally Consolidated Samples. 122 Effect of Soil Location on NSP from CKoUC Tests 123 Effect of Soil Location on the NSP from CKoUDSS Tests 124 Undrained Strength Data on Samples from Two Depths of Matagami Varved Clay 125 Experimental Program for Investigating the Effect of Stress System on SHANSEP NSP 196 Comparison of NSP from CIUC and CKoUC Tests on Connecticut Valley Varved Clays 197 Comparison of NSP from CIUE and CKoUE Tests on Connecticut Valley Varved Clays 198 Comparison of NSP from CIUE (8=900) and CIUC (e=00) Tests on Connecticut Valley Varved clays (Vertical Loading) 199 Comaprison of NSP from CIUE (8=0) and CIUC (8=900) Tests on Connecticut Valley Varved clays (Horizontal Loading) xi 200 Page Table No. Comparison of NSP from CKoU Triaxial, Plane Strain, and Special DSS Tests on Normally Consolidated Samples 201 Load Increments in CKoUDSS(C) and CKoUDSS(E) Tests on Normally Consolidated Inclined Samples 202 Estimation of Af from DSS Test Sample (=450) Using NESE Assumption 203 Summary of the Effect of Ac2 on Vertical Loading 204 Summary of the Effect of Aa2 on Horizontal Loading 205 Summary of NSP from CIUC Tests on Inclined Samples (0=450) 206 Results from Drained Direct Shear Tests on Northampton Varved Clay for Failure Within a Clay Layer 207 5.13 Summary of the Test Results from CKoUDSS Tests 208 5.14 Comparison of Typical Values of qf/vc, Tff/avc at (a /a 3 )max and Af from CIUC Tests on Inclined Samples and CKoUDSS Tests 209 Experimental Program for Investigating the Effect of Method for Minimizing Disturbance on Undrained Shear Strength Behavior 271 Comparison of Test Results from CKoU Tests on SHANSEP and RECOMPRESSION Samples from Connecticut Valley 272 Comparison of Test Results from CIUC Tests on SHANSEP and RECOMPRESSION Samples 273 Summary of Test Data from CIUC Tests for the Investigation of "Material" Anisotropy 308 Summary of Measured and Estimated Data from CKoUPSC, CK UDSS, and CKoUPSE Tests for the Study of Combined Anisotropy 309 5.6 5.7 5.8 5.9 5.10 5.11 5.12 6.1 6.2 6.3 7.1 7.2 8.1 Types of Stability Analyses and Recommendations for Embankments on Connecticut Valley Varved Clays xii 349 Page Table No. 8.2 8.3 8.4 Input Parameters for Connecticut Valley Varved Clays for Undrained Deformation and Pore Pressure Analyses Using FEECON 350 Soil Parameters for the Estimation of Initial Settlement and Pore Pressure 351 Determination of Su at OCR = 1.0 from Plane Strain Loading Using Strain Compatibility Method 352 Determination of S at OCR = 1.0 from Triaxial Loading Using Strain Compatibility Method 353 Determination of S by Using Strain Compatibility Method for riaxial Loading at OCR=2 354 Determination of Su by Using Strain Compatibility Method for Triaxial Loading at OCR=4 355 8.7 Determination of Su by the Author's Approach 356 8.8 Comparison of Su values from Ladd (1975), Author, and Corrected Field Vane Strengths 356 8.5 8.6(a) 8.6(b) xiii LIST OF FIGURES Page Fig. No. 1.1 2.1 Locations of Soil Samples of Varved Clays from Connecticut Valley Definition of Undrained Shear Strength Aniso- 47 tropy 2.2(a) In Situ and Applied Stresses in Field Situation of Elements 2.2(b) 2.3 2.4 2.5 2.6 48 A, B, and C. Testing Methods for Investigating the Undrained Shear Strength Anisotropy of Varved Clays in the Laboratory 49 Davis-Christian (1971) Elliptical Anisotropic Strength Relationship 50 Modified Mohr-Coulomb Failure Criteria for CrossAnisotropic Soil (After Merkle, 1971) 51 Summary of Results from UUC Tests oh Connecticut Valley Varved Clays (Data from Healy, 1967; Ladd and Wissa, 1970; and Long, 1975) 52 Anisotropic Behavior of London Clay at the Site of the Ashford Common Shaft Measured from CIUC Tests on Vertical and Horizontal Samples (Data from Bishop 2.7 53 et al., 1965) Test Data from CIUC Tests on OC Welland Clay Samples with Different Inclinations (From Lo, 54 1965; and Lo, 1966) 2.8 Anisotropy in qf and Af of Fulford Soft Clayey Silt Measured from CIUC tests on Samples with Different Inclinations (Data from Perry and Nadarajah, 2.9 2.10 55 1974) Test Data from CIUC Tests on Laboratory Prepared Vertical and Horizontal Samples of OC Kaolin (Duncan and Seed, 1966) 56 Test Data from CIUC Tests on Horizontal and Vertical Samples of a Laboratory Prepared Lightly Overconsolidated Kaolin (Data from Mitchell, 57 R.J., 1972) 2.11 5 Effect of c on the Measurement of Undrained Shear Strength Anisotropy of Connecticut Valley Varved Clay (After Long, 1975) xiv 58 Fig. No. 2.12 2.13 3.1 3.2 Page Anisotropy in S (S = fma) from CK UDSS Tests on Samples withuDi~feren inclinations (Option 5) of Three Soft Clays (Data from Soydemir, 1972) 58 Anisotropic Undrained Strength Ratio. Versus Plasticity Index 59 Results of Consolidation Tests on East Windsor Varved Clay 92 Soil Profile, Atterberg Limits, Recompression Ratio, and Virgin Compression Ratio of Amherst Varved Clay 93 3.3 Soil Profile, Stress History and Undrained Strength Data at Amherst, Massachusetts 94 3.4 Summary of Atterberg Limits and Compressibility of Northampton Varved Clay (From Ladd and Wissa, 1970) 3.5 95 Summary of Stress History, Undrained Shear Strength of Northampton Varved Clay (From Ladd and Wissa, 1970) 3.6 96 Summary of Consolidation Data at Boring 65 and 65A, Secaucus, New Jersey (from Saxena, et al., 1974) 97 3.7 Schematic Diagram of Essential Elements in Triaxial Extension Test 98 3.8 Diagramatic Drawing of Plane Strain Sample and Loading Systems 4.1 Normalized Stress-Strain Curves from CK UC Tests on Overconsolidated Amherst Varved Clay at Two vm(L)/vm Ratios 99 126 4.2 Normalized Stress-Strain Curves from CKUDSS Tests on Normally Consolidated Northampton Varved Clay 127 4.3 Effect of MPPR on Values of 3 G/avc from CKoUDSS Tests on Northampton, Amherst, East Windsor and Hackensack Valley Varved Clays 128 Comparison of Stress-Strain Curves from CIUC and CIUE Tests on Normally Consolidated Vertical Samples from Amherst, East Windsor and Hackensack Valley 129 4.4 xv Fig. No. 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 Page a/C -E Curves from CIUC and CUE Tests on Nrm~lly Consolidated Vertical Samples from Amherst, East Windsor and Hackensack Valley 130 Comparison of Stress-Strain Curves from CIUC Tests on Inclined Samples (450) of Normally Consolidated Amherst and East Windsor Varved Clays 131 Comparison of Stress-Strain Curves from CIUC Tests on Horizontal Samples of Normally Consolidated Amherst and East Windsor Varved Clays 132 Normalized Stress-Strain Curves from CKoUC Tests on Normally Consolidated Vertical Samples from Connecticut Valley 133 Normalized Effective Stress Paths from CKUC Tests on Normally Consolidated Vertical Samples from Connecticut Valley 134 Pf Versus qf at Maximum Shear Stress from CK UC Tests on Normally Consolidated Vertical Sampes from Connecticut Valley 135 Comparison of Normalized Stress-Strain Curves from CK UC Tests on Overconsolidated Amherst and Ease Windsor Varved Clays 136 A and c Versus OCR from CK UC Tests on Amherst and East Windsor Varved Clays 137 Effects of Soil Location on Normalized Effective Stress Envelope at Maximum Shear Stress 138 Normalized Undrained Shear Strength of Connecticut Valley and Hackensack Valley Varved Clays 139 Normalized Stress-Strain Curves from CK UDSS Tests on Normally Consolidated Northampton, Amherst, East Windsor and Hackensack Valley Varved Clays 140 Versus av/avm of ConnectiNormalized Thma /a cut Valley an~ aclRnsack Valley Varved Clays from CKoUDSS Tests 141 Normalized Stress-Obliquity-Strain from CK UE Tests on Overconsolidated Amherst and East Windsor Varved Clays 142 xvi Fig. No. 4.18 Page Af and Ef Versus OCR from CK UE Tests of East Windsor and Amherst Varved Clays 143 Comparison of the Normalized Undrained Shear Strengths of Connecticut Valley, Matagami and New Liskeard Varved Clays 144 Volume Change Data from CIU and CK U Tests with Horizontal Varved (=0 0 ) 'Samples from East Windsor 210 5.2 Ko Versus OCR for Connecticut Valley Varved Clay 211 5.3 Normalized Stress-Strain Data from CIUC and CKoUC Tests on Normally Consolidated Amherst Varved Clay 212 Normalized Stress-Strain Curves from CIUC and CK0 UC Tests on Overconsolidated (OCR=4) East Windsor Varved Clay 213 A Versus OCR from CUC, CKoUC, CIUE and CKoUE Tests on Connecticut Valley Varved Clays 214 e Versus OCR from CIUC, CKoUC, CIUE and CKoUE Tsts on Connecticut Valley Varved Clay. 215 Typical Normalized Effective Stress Paths for CIU and CK U Triaxial Compression and Extension Tests on N 8 rmally Consolidated and Overconsolidated Connecticut Valley Varved Clays 216 4.19 5.1 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 Normalized Effective Stress Envelopes from CIUC and CK UC Tests on Connecticut Valley Varved Clay:s 217 Eu/qf Versus Aq/Aqf from CIUC and CK UC Tests on Samples from Connecticut Valley 0 218 Eu/avc at e = 0.2% Versus OCR from CIUC, CKoUC, CIUE, and CKoUE Tests on Samples from East Windsor 219 Normalized Stress-Strain Curves from CIUE and CKoUE Tests on Normally Consolidated East Windsor Varved Clay 220 Normalized Stress-Strain Curves from CIUE and CK UE Tests on Overconsolidated (OCR=4) Conne8ticut Valley Varved Clays 221 xvii Fig. No. 5.13 5.14 Page EU/Su Versus Aq/Aqf from CIUE and CKoUE Tests on Samples from East Windsor States of Stress for CIUC CIUE (8=900) and CIUC (= 5.15(a) 5.15(b) 5.16(a) 5.16(b) (=0e), CiUE (=00), 900) Test Samples Normalized Stress-Strain Curves for Normally Consolidated CIUE (=900) and CIUC (=00) Test Samples (Vertical Loading) 5.18 5.19 5.20 5.21 5.22 5.23 5.24 223 224 Normalized Stress-Strain Curves for Overconsolidated CIUE (=900) and CIUE (=0 e) Test Samples (OCR=4) 225 Normalized Stress-Strain Curves for Normally Consolidated CIUE (=0 °) and CIUC (=90) Test Samples (Horizontal Loading) 226 Normalized Stress-Strain Curves for Overconsolidated CIUE (=00) and CIUC (=00) Test Samples (OCR = 4) 5.17 222 227 Normalized Effective Stress Envelopes from CIUC and CIUE Tests on Vertical and Horizontal Samples of Connecticut Valley Varved Clays 228 Effect of Intermediate Principal Stress on Normalized Octahedral Stress Paths 229 Effects of a2 : Normalized Effective Stress Paths from CIUC and CIUE Tests on Vertical and Horizontal Samples of East Windsor Varved Clay 230 Normalized Stress-Strain Curves of Normally Consolidated Samples from CKoUC and CKOUPSC Tests 231 Normalized Stress-Strain Curves of Normally Consolidated Samples from CKoUE and CKoUPSE Tests 232 Normalized Effective Stress Paths for Plane Strain and Triaxial Shear or Normally Consolidated Connecticut Valley Varved Clays 233 Comparison of Eu/F. from eK U Plane Strain, Triaxial and Speciai DSS Tests 234 Estimation of qf/Uvc of Overconsolidated Plane Strain Horizontal and Vertical Loading Samples from Connecticut Valley Varved Clays 235 xviii Fig. No. 5.25 Page Assumed State of Stress (Pure Shear~for Measuring Su(V) and SU(H) of Inclined (45 ) Normally Consolidated Samples from CKoUDSS(C) and CKoUDSS(E) Tests 236 5.26 NESE at (/3)max 237 5.27 Normalized Stress-Strain Curves of'Normally Consolidated Inclined Samples from CKoUDSS(C) and CKoUDSS(E) Tests 238 Comparison of qf/Uvc from CKoU Triaxial Tests and CKoUDSS Tes'ton Inclined Samples from East Windsor (Using NESE Assumption) 239 Comparison of qf/v Values from NESE Assumption and the Pure ShearVAssumption 240 NESE at qf and (l/Gmaxfrom CIUE Tests on Inclined Samples and CDDS Tests 241 NESE at (al/a3)max for Failure Within the Clay Layer 242 Typical Normalized Stress-Strain Curves from CKoUDSS Tests on NC and OC Connecticut Valley Varved Clays 243 Method of Computing qmax from CKOUDSS Test- on Normally Consolidated Amherst Varved Clay (Assumed NESE at qf from CIUC Tests on Inclined Samples) 244 Method of Computing qf from CKoUDSS Test on OverConsolidated (OCR=2) Northampton Varved Clay at Th (Assumed NESE at qf from CIUC Tests on InclileM Samples) 245 Method of Computing qf from CKoUDSS Testson OverConsolidated (OCR=4) East Windsor Varved Clay at (Th)pax (Assumed NESE at qf from CIUC Tests on Incllned Samples) 246 Determinations of Tests 247 5.28 5.29 5.30 5.31 5.32 5.33 5.34 5.35 5.36 5.37 5.38 for Failure Across the Varves ff at (Th/av)max from CKoUDSS Failure Strains at Thma and (Th/ )max from CKoUDSS Tests on Connecicut Varved Clay Computation of Relative Magnitudes of qf/v, Tof and Thmax/aVC by Assuming Two Locations ofNESE v/249 xix 248 Fig. No. 5.39 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 Page Comparison of the Effect of Stress System on qf/vc Versus OCR for Three Different Directions of Loading 250 General Effects of Disturbance on UUC Test, RECOMPRESSION and SHANSEP samples. 274 Effect of Method of Consolidation on Vertical Undrained -c- Strength Behavior from Triaxial Compression Tests on East Windsor Varved Clay OCR = 4 275 Effect of Method of Consolidation on Vertical Undrained a-c- Strength Behavior from Triaxial Compression Tests on East Windsor Varved Clay at OCR=2 276 Normalized Effective Stress Envelopes from CU Tests on SHANSEP and RECOMPRESSION Varved Clay Samples from Connecticut Valley (Data from Both Amherst and East Windsor for SHANSEP Samples) 277 Normalized Stress Paths from CK U Tests on SHANSEP and RECOMPRESSION Samples from Connecticut Valley 278 Compari-sonof qf(V)/vc from CKoUC Test SHANSEPSamples and UU Test Samples from Amherst and Northampton 279 Comparison of qf(V)/Uvc Versus OCR from C UC, CIUC and UU(V) Tests on SHANSEP and RECOPRESSION Samples of Amherst and East Windsor Varved Clays 280 Effect of Method of Consolidation on Horizontal Undrained -eStrength Behavior from Triaxial Tests of East Windsor Varved Clay at OCR = 4 281 Effect of Method of Consolidation on Horizontal Undrained ao-- Strength Behavior from Triaxial Tests of Connecticut Varved ClayTat OCR = 2 282 Eu/avc at 1/2 Aq/Aqf from CKoUC and CKoUE Tests on SHANSEP and RECOMPRESSION Samples from Connecticut Valley 283 Comparison of qf(H)/a c Versus OCR from CKoUE CIUC (=90) and UU ( 90°) Tests on SHANSEP and RECOMPRESSION Samples of Amherst and East Windsor Varved Clays xx - 284 Page Fig. No. 6.12 6.13 6.14 Normalized Stress-Strain Curves from CIUC (8=900) Tests on SHANSEP and RECOMPRESSION Samples (OCR= 4) from East Windsor 285 Normalized Stress Strain Curves from CIUC (=90 0 ) Tests on SHANSEP and RECOMPRESSION Samples (OCR= 2) from East Windsor 286 Normalized Stress-Strain Curves from CIUC (8=450) Test on SHANSEP and RECOMPRESSION Samples (OCR= 4) from East Windsor 287 6.15 NESE from CIUC (8=450 ) Tests on SHANSEP and RECOM288 PRESSION Samples 6.16 Comparison of qf/avc Versus OCR from CIUC (=450°) KOUD~SS, and UU (450 ) Test onSHANSEP and RECOMPRESSION Samples from Amherst and East Windsor 289 Comparison of G/a aty = 1.0% from CKdUDSS Tests on SHANSEP and RESMPRESSION Samples 290 Comparison of qf/avc from CIUC and CK UC Tests on SHANSEP and RECOMPRESSION Samples 291 Effect of Sample Orientation on Stress Versus Strain from CIUC Tests on Samples of Normally Consolidated East Windsor Varved Clay 310 Effect of Sample Orientation on Stress Versus Strain from CIUC Tests on Samples of Overconsolidated (OCR=4) East Windsor Varved Clay 311 Anisotropy in qf/ayc and Af of Connecticut Valley Varved Clay Resulting from Material" Anisotropy Component 312 Normalized Effective Stress Paths and Envelopes from Connecticut Valley Varved Clay at Different Varved Inclinations 313 "Material" Anisotropy in Pore Pressure and Pore Pressure Parameter A ate = 1.0% 314 7.6 Anisotropy in Undrained Modulus from CIUC Tests 315 7.7 Comparison of Anisotropy in qf Measured from Plane Strain and CIUC Tests 316 6.17 6.18 7.1 7.2 7.3 7.4 7.5 7.8 Effect of Structural Anisotropy Component Anisotropy on 317 in q xxi Fig. No. 7.9 Combined Anisotropy in qf of Connecticut Valley Varved Clay Measured from CKoU Plane Strain Tests 7.10 Estimated Combined Anisotropy in NESE from Plane Strain Loading 7.11 Anisotropy with Respect to G/3v of Normally Consolidated East Windsor Varvea Clay at Various Applied Shear Stress Levels 320 7.12 of Normally Anisotropy with Respect to G/. = 0.1% 321 Clay at VarvXa East Windsor Consolidated 8.1 Consideration of Anisotropy in Undrained Shear Strength in Morgenstern-Price Analyses (After 8.2 Recommended Su/avc for Total Stress Analyses by Ladd 8.3 357 1975) Ladd, - 358 (1975) Comparison of Simplified Bishop Circular Arc and Morgenstern-Price Analyses (from Ladd and Foott, 359 1977) Comparison of Normalized Undrained Shear Strength Data from UUV, FV and Thesis's Recommended Undrained Shear Strength Parameters for Design 360 8.5 SHANSEP EU/Su Versus OCR for Connecticut Valley Varved Clays 361 361 8.6 Recommended Initial Stress Ratio Versus OCR for Connecticut Valley Varved Clays for Plane Strain Loading 362 Settlement Ratio Versus Applied Stress Ratio for Load on Isotropic Homogeneous Foundation (from D'Appolonia, Poulos and Ladd, 1971) 363 Recommended Pore Pressure Parameter A Versus OCR for Predictions of Pore Pressure in Connecticut Valley Varved Clays for Plane Strain Loading 364 8.4 8.7 8.8 xxii Fig. No. 8.9 8.10 8.11 8.12 9.1 9.2 9.3 9.4 Page Recommended Undrained Hyperbolic Stress-Strain Parameters for Use in Finite Element Analyses with Connecticut Valley Varved Clays 365 Recommended Vertical Undrained Strength for Use in Finite Element Analyses with Connecticut Valley Varved Clays in Plane Strain Loading 366 Recommended Elliptical Anisotropic Undrained Strength Parameters for Use in Finite Element Analyses with Connecticut Valley Varved Clays 367 Recommended Pore Pressure Parameter a Versus OCR for Use in Finite Element Analyses with Connecticut Valley Varved Clays 368 Material and Combined Anisotropy in q Connecticut Valley Varved Clays at OC 377 of = 4 Combined Anisotropy in qf and in NESE at qf at (l/53)max 378 Recommended Anisotropic Undrained Strength Parameters for Use in Total Stress MorgensternPrice Stability Analyses with Connecticut Valley Varved Clays 379 Effect of Method of Consolidation on Vertical and Horizontal a-c- Strength Behavior from CKoUC and CKoUE Tests on Connecticut Valley Varved Clays at OCR = 2 380 xxiii 1. 1.1 INTRODUCTION BACKGROUND A varved clay is a rythmite or a rythmically layered sedi- ment comprised of two layers and a couplet. generally glacial lake deposits. Varved clays are Each varve represents the deposition during a year, and is composed of a lower part of coarser grained material deposited in the summer and an upper finer grained part deposited in the winter. The composition of varved deposits can vary from alternating layers of highly plastic clay and clayey silt (typical of varved clays in northern US and Canada) to alternating layers of silt and medium to fine sand. The thickness of the varves also varies consider- ably, although 1/4 to 2 1/4 in,is most typical. There'is gen- erally a gradual transition of the soil composition within a varve, but there is an abrupt change between varves resulting from the rapid influx of sediments during the runoff season. The strength, deformation and permeability characteristics of varved clays are highly anisotropic as a result of this layering. A three-year research program entitled, "The Behavior of Varved Clays in Civil Engineering Structures," sponsored by the Massachusetts' Department of Public Works in cooperation with the US Department of Transportation Federal Highway Administration, was conducted by the Constructed Facilities Division of the Department of Civil Engineering at MIT. 1 The final objective of the program was development of field and laboratory procedures that can be used with confidencein conjunction with realistic theoretical models for the design of civil engineering structures, and especially embankments, on varved clays encountered in the Connecticut Valley. In order to achieve this objective, it was necessary to: 1. Develop a better understanding of the fundamentals controlling the anisotropic engineering properties of varved clay; 2. Develop an experimental approach and theoretical model for predicting the engineering performance of varved clays; 3. Evaluate the reliability of these procedures based on case studies of the actual performance of structures on varved clays. At the conclusion of the above research project, Ladd (1975) presented detailed recommendations for the foundation design of embankments constructed on Connecticut Valley varved clays. This report had to be prepared before research on the fundamentals controlling the undrained stress-strain-strength properties of varved clay, the topic of this thesis, was completed. 1.2 OBJECTIVES The thesis concentrates on a study of the fundamentals of the undrained shear strength anisotropy of varved clays. 2 The objectives are: 1. To contribute to a fundamental understanding of the nature of undrained shear strength anisotropy of varved clays; 2. To present best estimates of normalized stressstrain strength parameters for undrained total stress analyses and for predictions of pore pressures and undrained deformations used in the design of structures on Connecticut Valley varved clays, with background information showing how these parameters were developed; 3. To recommend suitable testing procedures for developing normalized soil parameters for other varved clay deposits. 1.3 SCOPE In order to achieve these objectives, it is necessary to study: 1. The normalized behavior of several varved clays using consolidated undrained shear tests; 2. The effects of stress system* and sample disturbance on the normalized stress-strain-strength parameters of varved clays; 3. Suitable laboratory methods for measuring the undrained shear behavior of varved clays; *This denotes the applied stress conditions during consolidation and shear. 3 4. The fundamental factors controlling the anisotropic behavior of varved clays. A laboratory testing program was conducted at MIT on four varved clays. These were located in the Connecticut Valley at Amherst and Northampton in Massachusetts and at East Windsor, Connecticut and in the Hackensack Valley at Secaucus, New Jersey. The geological formation of the latter soil is similar to that of the Connecticut Valley. Fig. 1.1 shows the location of the three Connecticut Valley varved clays. The basic background and literature review of the anisotropic behavior of cohesive soils are presented in Chapter 2. Chapter 3 presents the general testing program and description of the varved clays, while Chapter 4 investigates their norma- lized soil properties (NSP). Chapters 5 through 7 study the fundamental factors influencing the anisotropic behavior of varved clays. The recommended NSP are presented in Chapter 8 with the necessary background showing how these parameters were developed. 4 cn J 0 w -J Uo ' a< p CfZ LL0 z0O) J 5 FIGURE 1.1 2. 2.1 BACKGROUND INTRODUCTION The object of this chapter is to provide basic background on the subject of undrained shear strength anisotropy. Since the study of this subject yielded rather conflicting results, an attempt is made to include a fairly detailed summary of available information. The normalized soil properties (NSP) concept of Ladd and Foott (1974) will also be presented because it is used throughout the thesis. Experimental data on undrained shear strength anisotropy are also reviewed. Appendix A lists the notation used in this thesis. 2.2 BACKGROUND 2.2.1 Ansiotropy in Undrained Shear Strength Definitions: The term anisotropy means that the proper- ties vary with direction of the measurement. Anisotropy of un- drained shear strength denotes variation in the undrained shear strength with the direction of loading. The convention that will be used to define direction is shown in Fig. 2.1. The angle B is the angle between the major principal stress at failure (alf) and the vertical direction in the ground. Aniso- tropy of the undrained shear strength, therefore, implies a variation in undrained shear strength with measured in the laboratory using tests with different directions of alf and with controlled magnitudes of the applied intermediate principal 6 stress (A62). Causes and Types of Anisotropy: The anisotropic undrained strength behavior of cohesive soil is intimately connected with "soil structure" (Lambe, 1958) which in turn depends on the environmental conditions during soil deposition, environmental and stress changes subsequent to deposition, and the applied stress system during shear. Stress changes subsequent to the deposition most frequently result from changes in the overburden pressure and in the ground water table elevation, including desiccation. It is convenient, according to Ladd et al. (1977), to divide undrained shear strength anisotropy, as measured in the laboratory, into three components, as follows: (1) Inherent Anisotropy -- This component of strength anisotropy is a direct result of the in situ soil structure. Soil structure is affected by the arrangement of the soil particles, which in turn depends upon the environmental conditions during deposition and the geological stress history. The one- dimensional consolidation which prevails during the geological stress history of most sedimentary clays causes the platelyshaped soil particles to have a tendency to align themselves at right angles to the direction of the major principal stress (e.g., Martin and Ladd, 1975). As a result, when a clay is loaded in a direction such that the failure surface is horizontal or nearly horizontal, it may have the lowest shear strength (Perry, 1971; Merkle, 1971). This type of inherent anisotropy is therefore termed the "structural" anisotropy. 7 Inherent anisotropy also occurs if the material is non-homogeneous. The prime example of this type of anisotropy is with varved clays due to the presence of clay and silt layers, each of which has different stress-strain-strength characteristics. 'Thiswill be In addition, each layer may also called "material" anisotropy. exhibit structural anisotropy. (2) Stress System Induced Anisotropy -- This component of undrained strength anisotropy results from the fact that different increments of shear stress are required to produce failure as the major principal stress at failure, lf' varies between the vertical and the horizontal direction, when the coefficient of earth pressure at rest (K ) is not equal to unity. Hansen and Gibson (1949) first discussed the existence of a stress system induced anisotropy and predicted large variations in undrained shear strength with direction of loading for isotropic soils (i.e., no inherent anisotropy) with constant values of the effective strength parameters (c and lent of Skempton's (1954) pore pressure ) and of the equivaparameter, Af. essence, stress system induced anisotropy results in in effective stress as In changes lf varies in direction during shear. (3) Combined Anisotropy -- "Combined" anisotropy (used in place of the term "in situ" anisotropy because anisotropic behavior is generally measured via laboratory tests) includes the total effects of inherent and stress system induced anisotropy. Ko consolidated undrained (CKoU) plane strain tests* i.e., plane strain compression (PSC) and plane strain extension (PSE). 8 run on vertical samples should measure the combined effect of inherent and stress system induced aniostropy for plane strain loading conditions in the vertical and horizontal direction because the anisotropic fabric is oriented in the same direction as in situ,and because shear starts from a K consolidation. However, with CK U triaxial tests, the directional variations in strength shown by comparing data from triaxial compression (TC) tests ( = 0) and triaxial extension (TE) tests (B = 900) result both from the total effect of anisotropy (inherent and stress system induced) and the differences in the magnitudes of the intermediate principal tests while Ao>1 Ao2 = A 3 stress (Aa2 ). [Aa1 = a2 > Aa 3 in TE in TC tests.] Section 2.2.2 will discuss the problems associated with various types of laboratory strength tests for predicting in situ shear strength anisotropy. 2.2.2 Measurement of Undrained Shear Strength Anisotropy Figure 2.2(a) shows states of stress for three typical soil elements along a potential sliding surface beneath an embankment. For simplicity, straight lines are used to represent the failure surface. The stress components shown reflect both the initial in situ stress on the failure surface (i.e., Tao' Tao) and the incremental (decremental) effects (AT-) due to subsequent undrained shearing caused by construction of the embankment. At Point A, the major principal stress at failure is in the vertical direction (i.e., B = 0) while it acts in the hori- zontal direction at Point C ( = 90°). 9 At an intermediate location such as Point B, the major principal stress at failure is inclined. Thus, unless K is unity, the principal stresses are rotated during shear at Points B and either A or C. Types of laboratory consolidated-undrained shear tests that might be used to measure the undrained shear strength of Points A, B, and C are shown in Fig. 2.2(b). For Point A, a vertical sample can be sheared in triaxial or plane strain compression (TC or PSC), after Ko consolidation for Method Al. An inclined sample can also be tested in a direct simple shear (DSS) test for Method A 2 (Bjerrum, 1973). At Point B, Ko con- solidated undrained direct simple shear (CKoUDSS) tests run on vertical samples, or isotropically consolidated undrained triaxial compression (CIUC) tests performed on inclined samples might be used, Method B1 and B 2, respectively. K o consolidated undrained (CKoU) triaxial and plane strain extension (TE and PE) tests on vertical samples and isotropically consolidated undrained (CIU) triaxial compression tests on horizontal* samples could be used to simulate the state of stresses at Point C for Methods C 1 and C 2. A CKoUDSS test on an inclined sample, varved inclination 8 = 450, which is sheared by reversing the direction of the applied shear stress can be used to measure the strength at Point C for Method C 3. Figure 2.2(b) shows the states of stress acting on the soil samples during consolidation and subsequent shear for each method. It should be noted, however, *Horizontal sample means that the axis of the sample is cut from the in situ horizontal direction (i.e., °0 = 90 for varved clay; and the specimen varves are vertical). 10 that only the stress components that can be measured are shown for methods involving the direct simple shear test. Both conventional and sophisticated methods of investigating undrained strength anisotropy are summarized in Table 2.1. The problems associated with these approaches are also outlined. Many investigators (e.g., Bjerrum and Landva, 1966; Beere, 1969,; Bjerrum, 1973; and Ladd et al.; 1977) are convinced that undrained shear strength and its anisotropy can only be reliably measured in the laboratory provided: the samples are consolidated anisotropically and sheared with the same stress system as in the field. These researchers have de- veloped their "standard" procedures for measuring "anisotropy." They include K o consolidated triaxial compression and extension tests (or less frequently plane strain compression and extension tests) for vertical and horizontal loadings respectively (Points A and C) and a direct simple shear test for inclined loadings (Point B). Since the CK UDSS test can cause a rota- tion of principal planes during shear, Bjerrum (1973) also suggested Methods A 2 and C 3 in Fig. 2.2, i.e., Option 5 in Table 2.1. Table 2.1 also lists problems associated with each option. Unconsolidated undrained triaxial compression (UUC) tests, Option 1, can at best yield only crude estimates of anisotropy because of sample disturbance. Furthermore, shear starts from an isotropic state of stress, and therefore neglects the stress system induced component. With CIUC tests, wherein samples 11 are usually consolidated to the effective vertical overburden stress (avo) or less, Option 2, the effect of sample disturbance may be somewhat reduced, but isotropic consolidation will undoubtedly cause some change in the initial structure anisotropy. Also, as with Option 1, there is no stress system induced anisotropy during the actual shearing process. Option 3 uses Ko consolidated triaxial compression and extension tests and the direct simple shear test. three different pal stress (2 = values of the intermediate princi- 3 in triaxial rect simple shear, and 1 = This involves compression, a1 > 2 > 3 in di- 2 in triaxial extension), and thus, can not be directly used to obtain the in situ directional variation of undrained shear strength unless variations in the intermediate principal stress have little effect on the undrained shear strength (or the data are corrected for estimated effect of this factor). The DSS test also has problems with interpretation of the results, since the state of stress at failure is unknown. parameters, c and Consequently, the effective shear strength ~, and Skempton's pore pressure parameter, Af, can not be directly measured (Ladd and Edgers, 1972). Fur- thermore, it is not certain what the measured maximum horizontal shear stress (thmax) represents. It is generally less than the maximum shear stress (qf) and may be, even less than the shear stress on the failure plane at failure, Tff 5.4). (see Section Because of the presence of the cylindrical wire rein- forced rubber membrane,the non-uniform stresses and possibly 12 progressive action (especially at the edges of the sample) exist in the DSS test. In Option 4, use of plane strain equipment often presents problems due to friction forces that are generated along the loading piston and along the vertical boundaries of the samples. Unless these friction forces are measured, one is never sure of the reliability of the data. In Option 5, the direct simple shear test has the same problems associated with tation of test results, as discussed above. interpre- In addition, there are two problems with tests simulating Points A and C. The first is that K o must be known or estimated in order to apply the correct value of a and Tao (see Fig. 2.2(b)). The second is that the consolidation stresses perpendicular to this plane can not be controlled. Thus, based on the above discussion, all options involve problems of a different nature and magnitude. Option 4 is theoretically the best if reliable plane strain equipment is available; if not, Option 3 or 5 offer the most attractive alternatives. 2.2.3 The Normalized Soil Properties (NSP) Concept The normalized soil properties (NSP) concept is used to study the undrained shear strength behavior of varved clays throughout this thesis. In this section, the basic ideas of the NSP concept arepresented. For further information on this subject, the reader is referred to Ladd (1971), Ladd and Foot 13 (1974) and Ladd et al. (1977). The NSP concept was developed from the following empirical observation that applies to many clays: the results of consoli- dated undrained (CU) laboratory shear tests performed on samples with the same overconsolidation ratio (OCR), but different consolidation stresses and therefore, different maximum past pressures ( vm vm), exhibit very similar strength and stressstrain characteristics when normalized with respect to the consolidation stress. Thus, it is possible to run laboratory tests at various OCR values and develop an unique normalized plot of soil parameters versus OCR. Examples of normalized soil parameters that can be used in such plots are the normalized maximum.'shearstress at failure (qf/avc), the normalized undrained Young's modulus (EU/ vc), Skempton's pore pressure parameter (Af), and (K). the coefficient of earth pressure at rest With a knowledge of the in situ stress history, perti- nent soil properties can then be computed. Measurement of NSP Laboratory measurement of engineering properties always involves effects of sample disturbance. In cohesive soils, sample disturbance reduces the undrained shear strength (qf) as measured in UUC tests (e.g., Ladd and Lambe, 1963; Davis and Poulos, 1967). But observations of compression curves from consolidation tests (Schmertmann, 1955) indicate that "disturbed" samples have approximately the same virgin compression characteristics as those of undisturbed samples provided that the 14 consolidation stress is beyond the maximum past pressure (and the degree of disturbance is not excessive). Thus, the effect of sample disturbance can be reduced if the soil sample is consolidated beyond the maximum past pressure into the virgin compression range. Based on this observation, Ladd and Foott (1974) suggest that for soils exhibiting normalized behavior, undrained strength parameters should be obtained from samples which are consolidated according to the SHANSEP approach. This involves consolidation of soil samples to stresses in excess of the in situ maximum past pressure in order to minimize sample disturbance effects, and subsequently reducing the effective stress to obtain samples at the required OCR values. Thus, this method not only reduces the effect of sample disturbance, but it also provides a sample of known OCR. For obtaining the appropriate SHANSEP NSP, the samples must be K consolidated to at least 1.5 to 2 times the in situ a vm and sheared with stress systems similar to the in situ conditions. Also, use of SHANSEP NSP (obtained from the above testing procedure) for estimating the in situ soil properties (qf, Eu etc.) requires a knowledge of the in situ stress history (vo and avm ), since NSP are related to OCR. Limitation of SHANSEP Method of Consolidation With highly structured soils (e.g., "quick" clays and naturally cemented soils), consolidation above the in situ stresses will cause radical changes in soil behavior. The SHANSEP method of consolidation, therefore, does not apply to 15 such soil. With these materials, the in situ stresses should be used for consolidation (Berre and Bjerrum, 1973) although this requires samples of exceptionally high quality if meaningful data are to be obtained. Recent work by Sangrey (1975) illustrated that the NSP concept could be used in cemented soils provided the soil parameters were normalized with respect to yield stress, defined as the maximum stress to which the samples can be consolidated without changing its basic behavior. In theory, if a soil truely exhibits normalized behavior, NSP from the SHANSEP method of consolidation should represent the in situ soil properties. In reality, almost all natural clays will undergo some change in structure when they are consolidated above the in situ vm. As a result, NSP from the SHANSEP samples, especially those of overconsolidated (OC) soils, may be different from those of the in situ soil. How- ever, this does not imply that the SHANSEP method of consolidation necessarily yields unsatisfactory NSP, especially when compared to those obtained from other methods (e.g., UU tests or CU with the RECOMPRESSION* Method). Since sample disturbance also causes changes in soil structure, data obtained by the other methods also yield soil properties which are different from those existing in situ. SHANSEP samples (a In fact, for most NC soils, > (1.5 to 2) avm) should have a structure *RECOMPRESSION: the method of consolidation whereby the sample is consolidated at the desired OCR with a vertical consolidation stress is less than the in situ maximum past pressure. 16 similar to in situ normally consolidated clay and hence yield reasonable NSP (Ladd et al. 1977). Chapter 4 will present the experimental evidence showing that for the stress range used in the study (which is rather small), the varved clays under investigation do indeed exhibit normalized behavior, at least with regard to certain properties. Chapter 6 then compares properties obtained via the SHANSEP method with those measured using other procedures. 2.3 LITERATURE REVIEW Two areas of research for the study of the undrained shear strength anisotropy are considered. The first, the analytical approach, concentrates on the analytical presentation of undrained shear strength anisotropy and includes (1) curve fit- ting methods to describe anisotropy using empirical equations and semi-theoretical relations; and (2) theoretical predictions wherein, after hypothesizing possible causes of shear strength anisotropy, "theoretical" anisotropic shear strength relations are derived. The second approach is experimental, in which possible causes and the factors influencing undrained shear strength anisotropy are investigated. Section 2.3.1 will review the analytical approach, including both curve fitting methods (Section 2.3.1(a)) and theoretical predictions (Section 2.3.1(b)). Possible factors affecting the aniostropic shear strength behavior of varved clay, using isotropic Mohr-Coulomb failure theory, are presented in Section 17 2.3.1(c). from: CKoU Section 2.3.2 summarizes the experimental results UUC and CIUC tests on samples with different inclinations; triaxial, direct simple shear (DSS), and plane strain tests on vertical samples; and special CKoUDSS tests on samples with different inclinations. Since the effect of stress system on NSP is studied in Chapter 5, a brief review of the influence of the intermediate principal stress and the K consolidation on the strength behavior is presented in Section 2.3.3. 2.3.1 Analytical Approach 2.3.1(a) Curve Fitting Method The first curve fitting method,proposed by Casa- grande and Carillo (1944),for presenting anisotropic shear strength behavior is the equation: S ) = Su(H) +(Su(V) - Su(H))cos2 (Eq. 2.1) Their relationship was suggested originally as a working hypothesis without experimental justification. Davis and Christian (1971) later showed that experimental data from UUC tests on several relatively homogeneous soft clays (e.g., Welland clay, San Francisco Bay mud, and Kaolinite) fitted this relationship reasonably well. Bishop (1966) proposed a modification of Casa- grande-Carillo equation: Su(B) = Su(V) (1 - m sin2 ) (1 - n sin2 2) (Eq. 2.2) to fit UUC test data on London clay in which the parameters Su(V), m, and n are determined from laboratory tests (Bishop suggested using Su(V), S(45) and S(H) lishing these parameters). 18 as a minimum in estab- Davis and Christian (1971) proposed an elliptical anisotropic strength model to use in bearing capacity analyses. They modified the anisotropic yield criteria for metals (Hill, 1950 and Scott, 1963) to apply to cohesive soil as follows: (a Y - a S (V)-S (H)2 x u u 2 + 2 a xy b - a 2 2 (Eq. 2.3) Su(V) and SU(H) = the apparent undrained shear strength in compression in the vertical and horizontal directions. a and b = constants S U (V)+Su (H ) to be found experimentally. = a, and b/a = 2 (45) Su(V)S U (H) u In the polar plot such as shown in Fig. 2.3, the variation in undrained shear strength with angle 2 is elliptical. This equation was found to fit most existing UUC test data (Davis and Christian, 1971). 2.3.1(b) Theoretical Prediction of Anisotropic Behavior Hanson and Gibson (1949) recognized that K con- solidation could cause anisotropy with respect to undrained shear strength even in soil having isotropic Hvorslev (1960) effective shear strength parameters and Skempton's (1948) X parameter (the ratio of the slope of a swelling curve to the slope of the virgin consolidation curve). They first predicted the existence of stress system induced anisotropy (Ladd et al. 19 1977). Their expression for Su(=qf) for any orientation of the failure plane was in terms of the initial shear stress the Hvorslev shear strength parameters, the angle between the failure plane and the horizontal plane (a), and the change in pore pressure due to changes in total stress based on Skempton's (1948) "A theory." Duncan and Seed (1966(a)) re- viewed their work and modified the Hanson and Gibson equation to use isotropic Mohr-Coulomb effective stress strength parameters 4 and c and Skempton's pore pressure parameter Af. The equation in trms of c, ~ and Af for plane strain condition is S suu (a) c- Cc cos 4 + 1/2 (1+Ko)sin 4 - sinf(2Af-l) (a)2 [(S) Vc + /2 -) zivc 1-K + ( S (a) -u _ (1-Ko)cos2(45 2 1/2 (Eq. 2.4) 2 ) Although the theory is simplistic in that Af, c and are assumed constant, and therefore independent of the direction of loading, Eq. 2.4 predicts trends (shown in Table 2.2) which are amazingly realistic compared to test data on homogeneous clays reported in Tables 2.5 and 2.6. Baker and Krizek (1970) and Markle (1971) considered directional variations in 4 and c with failure plane inclinations (a). They independently developed equations for calculating the shear strength (qf) and the failure plane inclination in a 20 cross-anisotropic soil, given the values of Band pf (Markle, 1971), or and 03f (Baker and Krizek, 1970) provided the varia- tions of and c with a are known. The governing equations (Eqs. 2.5 to 2.7) from Markle's method (1971) are presented in Figs. 2.4(a) and 2.4(b). Based on the modified Mohr-Coulomb (M-C) failure criteria (i.e., and vary with failure plane inclin- ations (a)), for a given value of , failure in the soil occurs when the point representing the state of stress at failure (tff and aff) on the failure plane at orientation 6 lies on the corresponding failure envelope (only one envelope exists for given values of and f). As a result, the failure envelope can in the general case, intersect or be tangent to the Mohr circle. It is seen that the resulting equations are difficult to use (since the variations of and c with inclinations of failure plane (a) must be known) and they require know- ledge of pf for computing qf and the failure plane inclination (a). As a result, they have little practical value for predicting the variation in qf with , though the basic causes of ani- sotropy in qf are hypothesized. 2.3.1(c) Factors Affecting the Anisotropic Shear Strength Behavior of Varved Clay The variables that could affect 4 and c of varved clays were studied by Townsend et al. (1965). They presented the following general expression indicating the possible variables in the case where failure planes cut across the varves. tan ~ = (1 -nc) tan ~s + nc tan ~c 21 (Eq. 2.8(a)) c = (1 - n c) C s + and (Eq. 2.8(b)) c Cs p and c = M-C effective stress strength parameters where of bulk material %s and cs= M-C effective stress strength parameters of silt portion c and cc= M-C effective stress strength parameters of clay portion n c = % of clay layer in the failure plane The following are the assumptions used for developing Eq. 2.8: 1. The failure surface is a plane that intersects clay and silt layers at the same inclination. 2. Both silt and clay layer exhibit isotropy with respect to the effective stress strength parameters 4 , and c (i.e., c c s , s Cc and c s are independent c of failure plane inclinations). 3. The same off acts in both clay and silt layers. The above equation suggests that in the case where nc is constant, values of and c of varved clays will be constant. Thus, for homogeneous varved clay, there are three possible values of and c. These are: (1) for failure within the clay layer (i.e., n c = 1.0); (2) for failure within the silt layer (i.e., n = 0); and (3) for failure across the varves. Data in Chapter 5 will show, provided samples have the same failure mechanism (i.e., failure across the varves or failure within the clay layer), that values of and c at (a1/a3)ma of OC samples are constant and independent of failure 22 plane inclination. But for other conditions, i.e., (c=O) at (al/a3)max of NC soil or ' and c at qf (when they are not equal to those at (al/a3) ), it is not true. max 2.3.2 Experimental Approach The purpose of the literature review in this section is to synthesize experimental evidence from several cohesive soils regarding: (1) the possible causes of anisotropy in Su , and the factors influencing anisotropic behavior measured in laboratory tests. The presentation of results will be organized according to the types of laboratory tests, namely: UUC* and CIUC tests on samples with different inclinations; and CK0U tests such as those described in Table 2.1. Experimental re- sults from homogeneous clays and from varved clays are included. 2.3.2.(a) Evidence from UUC Tests Table 2.3 summarizes the data from UUC tests on differently inclined homogeneous samples (presumably measuring the inherent anisotropy) of six clays. The results illustrate the possible trends that may be encountered from UUC tests on homogeneous samples, as follow: (1) The isotropic trend: Jacobson (1955) reported results of 34 unconfined compression tests performed at various inclinations on sarhples.of post-glacial marine clay fromiStockholm. As shown in Table 2.3, the variation in qf is within the limit *The unconfined compression test is treated as a UUC test where oc is equal to zero. c 23 of the mean error. This apparent isotropic trend could be the result of sample disturbance which tends to mask undrained strength anisotropy of homogeneous clay (Ladd et al., 1977). (2) The anisotropic trend. As shown in Table 2.3, with the exception of test results from Kaolin (Mitchell, 1967; and Duncan and Seed (1966(b))and from Little Belt clay (Hvorslev, 1960), the horizontal strength is the weakest. Therefore, these data suggest, for homogeneous clays, as shown for UUC test data, that the lowest strength will be either in the inclined or horizontal loading direction. (ii) Non-Homogeneous Clay Non-homogeneous clays include stratified soils as well as varved clays. The London clay which has laminations and fissures is also included in this category. Table 2.4 and Fig. 2.5 summarizes data on non-homogeneous clays from several locations. These data show that samples inclined with to 45 to 60 degrees had the lowest strength. equal The UUC results for Connecticut Valley varved clays, summarized in Fig. 2.5, are of particular interest. The main points worthy for mention are: 1. The qf (45)/qf(V) ratio ranges from 0.3 to 0.5 2. The anisotropic effect is more pronounced in samples at shallow depth (WNI 50%) compared to those at greater depth. qf(H) (3) ) ratio is greater than one for varved clay located near the surface, and less than oneforsample 24 located at greater depth. This difference sug- gests that the stress history influences anisotropic behavior, i.e., the sample at shallow depth probably has a higher OCR. Sample disturbance in non-homogeneous clay may amplify the inherent anisotropic effect as measured with UUC tests. Ward et al. (1965) concluded that opening of the laminations in London clay (caused by disturbance during sampling) was likely to have little effect on shear strength unless the failure surface was nearly horizontal (generally observed in inclined loading) in which case the shear strength could be appreciably reduced. Disturbance due to separation of clay and silt layers in varved clay during sampling and trimming may also cause a significant reduction in qf(4 5 0 ) while qf(V) is slightly affected (see Chapter 6 and Section 2.3.2(b)). 2.3.2(b) Evidence from CIUC Tests The anisotropic behavior from CIUC tests on samples with different inclinations was measured for both undisturbed samples (Bishop et al., 1965; Lo, 1966, and Perry and Nadarajah, 1974) and laboratory prepared Kaolin samples (Duncan and Seed (1966(a)) and Mitchell (1972). Figures 2.6 to 2.10 summarize their results. Test data from Connecticut Valley varved clays (Long, 1975) are presented in Fig. 2.11. For the laboratory prepared Kaolin samples (Duncan and Seed, 1966(a); and Mitchell, 1972), the test specimens were anisotropically consolidated and then extruded so that the effective stress 25 immediately after sampling was due to a negative pore pressure and was therefore isotropic. The specimens were then isotropic- ally consolidated to stresses less than the a of the block sample before they were sheared, with the exception of two samples (vertical and horizontal) reported by Mitchell (1972) where c was greater than vc of the block sample. The undis- turbed soils are the OC Welland clay from Ontario (LO, 1966); the heavily overconsolidated London clay at Ashford Common Shaft (Bishop et al., 1965); an overconsolidated soft clayey silt from Fulford, England; and the Connecticut Valley varved clays. The available index properties and the UUC test data (only from Welland Clay (Lo, 1965) and Connecticut Valley varved clay Long (1975)) are also presented. These CIUC data, mostly for OC vertical and horizontal samples, show the following: 1. Data from London clay (Fig. 2.6) and laboratory prepared Kaolin (Figs. 2.9 and 2.10) show that the failure envelope in terms of effective stress (i.e., the effective stress strength parameters and ) was essentially the same for vertical and horizontal samples. The differ- ences in qf are therefore the result of the differences in Af and hence pore pressure developed during shear. Data from the soft clayey silt from Fulford (Fig. 2.8) show only slight differences in failure envelopes from vertical, 26 inclined, and horizontal samples (practically insignificant considering the difficulty in determining and c from the scatter of lab- oratory data). For the East Windsor varved clay, the anisotropy in qf is due to both the anisotropy in effective stress strength parameters and the pore pressure (Fig. 2.11). 2. The data from UUC and CIUC tests on Welland clay (Fig. 2.7) and the East Windsor varved clay (Fig. 2.11) show different trends with respect to anisotropy in qf. It is believed, however, that sample disturbance affected the UUC test results so as to decrease the anisotropy in qf for the Welland clay and to increase it for the East Windsor varved clay 3. (see Chapter 6). Based on test data from Welland clay (Fig. 2.7) and laboratory prepared Kaolin (Fig. 2.10), the excess pore pressure versus axial strain relation is unique for samples tested with various orientations, though Af samples 4. is different of these (since Ef is different). For both homogeneous and non-homogeneous soils (Figs. 2.6 to 2.11), the vertical strength (qf(V)) is larger than the horizontal strength (qf(H)). 27 5. An increase in the magnitude of isotropic consolidation stress ( ) in CIUC tests decreases the anisotropic shear strength behavior. Data from Figs. 2.6 and 2.8 to 2.11 indicate that qf(H) qf(H) qf(V) Af(H) andA ) approach unity as Af (V) c reaches vm for undisturbed soil or approach or exceeds vc of the block for laboratory prepared VC Kaolin samples. Test data from prior K con- solidated laboratory prepared Kaolin (Mitchell, 1972; in Fig. 2.10) in fact, showed that when a c exceeds avc of the block, the Kaolin behaved like an isotropic material. The stress-strain- pore pressure (a-e-u) behavior and thus the stress paths (plotsof q versus a + 3 53 ), of horizontal and vertical samples (shown as the dashed line in Fig. 2.9) are essentially identical. Therefore, the data in Figs. 2.6 and 2.8 to 2.11 (especially those in Fig. 2.9) sug- gest that the structural anisotropy component resulting from prior K consolidation which causes anisotropic behavior is reduced (or may even be completely eliminated if a exceeds avm) c stresses. vmconsolidation by high isotropic consolidation stresses. 28 2.3.2(c) Evidence from CK U Tests The total effect of the combined anisotropy (that resulting from the inherent and the stress system induced components) and the difference in the applied magnitudes of a2 (only when comparing data from TC and TE tests) on variations of S with , is measured with CKoU tests. This section will present the NC and OC anisotropic shear strength behavior data obtained from Options 3, 4, and 5 of Table 2.1. The variations of S U with loading direction, of several soft clays from these options are presented in Tables 2.5, 2.6, and 2.7 and Fig. 2.12. The data in Table 2.6 and Fig. 2.12 were obtained from the RECOMPRESSION ( VC = avo ) method of consolidation used by NGI.. The SHANSEP method of consolidation (avc > (1.5 to 2.0) a ) was used to obtain test data in Tables 2.5 and 2.7 for CK U plane strain and traixial test results. Su(DSS)* The strength ratios qf(H) and (V) from Options 3 and 4 (excluding Option 5 because of problems in the interpretation of test data) are presented in Figs. 2.13(a) and 2.13(b). The data from Tables 2.5, 2.6, and 2.7 and Figs. 2.13(a) and (b) show that: 1. The anisotropy in S is more pronounced in the lean sensitive clay (having lower PI) than in the plastic insensitive clays. 2. For both plane strain and triaxial loading , *See the definition in Tables 29 2.5 and 2.6. SU(H) of homogeneous clays is lowest, partly because of the effect of the rotation of prin- cipal planes and, for the triaxial tests, also 3. due to the difference in the magnitude of a2. qf(H) qf(V) ratio is affected by the type of test qf(v) (i.e., plane strain versus triaxial) and (perhaps) the method of consolidation. at same PI (Fig. 2.13(b)), Compared SHANSEP CK U o strain (Option 4) tests yield higher plane qsf(H) qf:(V ratios than those from RECOMPRESSION (a =a ) VC VO C--U triaxial (Option 3) tests,and to a lesser 0 extent, the SHANSEP CK U triaxial samples. Su(DSS) 4. Su (V) ratio is apparently affected little by the type of test and the method of consolidation. The test data from CK UDSS tests (Option 5, Fig. 2.12) give the variation of qf with sample inclination rather than the loading direction. It is seen that the maximum Su from CK oUDSS (C) tests occurs between sample inclinations of 40 to 45 degrees, and the minimum S from CK UDSS (E) tests occurs between sample inclinations of 50 to 60 degrees. Thus, the use of sample inclinations of 450 (see Chapter 5) should yield S values close to S maxfrom CK0 UDSS (C) tests and somewhat larger than Su min from CK UDSS (E) tests. 30 Table 2.7 also presents a summary of effective stress CKoUPSE, CKOUC and CK0 UE tests strength data from CKoUPSC, o on SHANSEP normally consolidated samples of several soft clays. It is seen that the direction of loading can cause differences in both and Af. It should be noted that, at the same av , a smaller Af in CK UPSE tests compared to in CKoUPSC tests, such as occurred with the San Francisco Bay Mud and AGS CH clay,does not mean that the extension tests had smaller pore pressure. Because of the larger magnitude of Aq required to cause failure, Pf/Ov CK0UPSE tests (when K value from the <1) can be lower than that from CK UPSC tests (i.e., the effect of stress system induced anisotropy). To illustrate this point, Pf/vc values from San Francisco Bay Mud (Duncan and Seed, 1966(b))are given below: Af qf/avc Pf/vc 0 CK UPSC 1.12 0.12 0.60 380 CK UPSE 0.70 0.57 0.49 350 Type of Test o Based on test data in Table 2.7, the differences in Af, Yf* and ~ from vertically and horizontally loaded samples are more pronounced in lean sensitive clays than in plastic insensitive clays. The stress history can also affect the combined *Defined in Table 2.7, based on linear isotropic elastic theory. 31 anisotropic behavior. Table 2.8 shows the effect of OCR on the qf, Af and Ef ratios from plane strain compression and extension tests on Boston Blue Clay. anisotropy in qf and increasing OCR. It is seen that the f decrease, but Af increases with The fact that the effect of the rotation of principal planes is more pronounced in NC samples than in OC samples (since K increases with increasing OCR) partly explains such trends. 2.3.3. Summary and Conclusions Based on the review test data from UUC, CIU and CKoU tests, the possible factors affecting the anisotropy in Su measured 1. in the laboratory are: Sample disturbance: For homogeneous clay, sample disturbance tends to mask the anisotropic effect measured with the UUC tests. However, for non-homogeneous clay, sample disturbance may increase the anisotropic effect. 2. The Magnitude of c: The use of high a , especially using ac >avm in CIUC tests on samples with different inclinations tends to minimize, if not completely eliminate, the structural anisotropy resulting from prior in situ K less K o consolidation. As a result, un- o is equal to 1, it is not possible 32 to truly separate the effect of stress system induced anisotropy from the combined anisotropy by comparing test data from CIUC tests (avc = avo ) on samples with different inclinations (presumably measuring the inherent anisotropy), and from CKoU tests on vertical samples (measuring combined anisotropy). Anisotropy is found to be more pronounced in the lean sensitive soils than in highly plastic clays. Based on limited data, the anisotropic behavior of cohesive soil is also dependent upon the in situ stress history. The magnitude the q(V) of the 2 used in the test can affect ratio... Test data from CKoU plane strain and triqf(H) axial tests show that the qf(v) ratios from plane strain tests are somewhat larger than those from triaxial tests. Such differences are thought to be due to the differences in the magnitudes of a2 between triaxial and plane strain loading. Data from both plane strain and triaxial tests on NC sample show that the directional variation of S (qf) with B is due to the directional variations of both the effec- tive stress strength parameter ~ at qf and the pore pressure. The directional variation in pore pressure is in turn the result of the directional variation of Af, and the difference in the magnitudes of Aqf. The larger mag- nitude of Aqf in a horizontally loaded sample, compared to 33 that in the vertically loaded sample, can cause larger pore pressures and a lower effective stress at failure, even though the Af for horizontally loaded sample is lower. For OC samples, based on data from CIUC tests on RECOMPRESSION samples of several homogeneous cohesive soils with different inclinations, the anisotropy in qf is due only to the anisotropy in pore pressure. strength parameters The effective stress and c at qf are practically unaffected by sample inclination. However, one should realize that CIUC test do not cause a rotation of principal planes during shear and thus, the directional variations in 4 and c could occur in the combined anisotropic behavior of OC soil. The interpretation of the anisotropic behavior of both NC and OC Connecticut Valley varved clay measured using SHANSEP method of consolidation will be presented in Chapter 7. 2.3.4 Effect of Certain Stress System Variables on Undrained Shear Strength Behavior This section summarizesexperimental data showing the general effects of intermediate principal stress and K 0 consolidation on undrained shear strength behavior. The effect of the intermediate principal stress is shown by comparing test data from CK0 U triaxial and plane strain tests. The results from NC and CKoUC (Ao>A =A3) T-rU PSC tests (A >a2>A )3 tests are compared for the inter- mediate principal' stress'effect in vertical loading. 34 For horizontal loading, results from CK UPSE tests (Aa1 >Au2 >AG3 ) o CKUE tests (A=Aa2>A of K 3) are compared. (versus isotropic consolidation The influence consolidation) is shown by comparing test data from CIUC and CKoUC tests, and from CIUE and CK UE tests for vertical and horizontal load- o ing respectively. 2.3.4(a) Effect of Intermediate Principal Stress Tables 2.9(a) and 2.9(b) summarize data from CK UPSC versus CK UC tests and from CK UPSE versus CK UE o o o o tests on several normally consolidated undisturbed and remolded clays. For San Francisco Bay Mud, Atchfalaya Clay, and remolded Weald Clay, only data for vertical loading are available. These data show that shearing in plane strain compared to that in triaxial: 1. Increases qf for both vertical and horizontal loadings. Such increases are larger for hori- zontal loading (up to 25%) thanfor the vertical loading 2. (an increase of about 10 to 15%). Generally decreases Yf* for both vertical and horizontal loadings. Such decreases are, however, larger for vertical loading than for horizontal loading. 3. Significantly increases loading, though 4 at qf for vertical 4 at (l/3)ma x is only *Defined according to Table 2.9 for triaxial and plane strain tests based upon linear isotropic elasticity theory. 35 slightly increased. the difference in For horizontal loading, at qf between TE and PSE test is somewhat smaller. 4. Does not consistently affect Af. is not to say, however, This that increase in a 2 will not increase Au. For an ideal isotropic soil, the intermediate principal stress will not affect the stress path in terms of octahedral stress (c t versus act) ference in the magnitude of For such a material, dif2 does not change the pore pressure parameter "a" defined below: Au =AcT + a Ar oct oct (Eq. 2.9) For vertical loading, test data from CK UC and CK UPSC o o tests on remolded Weald clay and natural Hanney clay show unique stress path in terms of octahedral stress. For hori- zontal loading, however, (i.e.,the data from CKoUPSE and CKoUE test), the octahedral stress paths are far from unique. 2.3.4(b) Effect of K Consolidation Ladd (1971) summarized the effect of isotropic versus K consolidation undrained (CU) triaxial compres- sion tests on several normally consolidated clays. Accord- ing to Ladd (1971), the results from NC clays generally show that K consolidation relative to the isotropic con- solidation: 1. Has a variable effect on qf/Ovc 36 the change being + 10 to 15%; 2. Generally decreases 3. Causes a substantial change in stress strain and Af at qf; behavior, with a much smaller strain at failure, and more strain softening; and 4. Little change in at (/a3)max For horizontal loading, NC test data on Boston Blue clay (Ladd and Varallyay, 1965) indicate a significant decrease in qf and Af and a slight increase in with K con- solidation. For OC samples, test data from CIUC, CK UC, CIUE and CK UE tests on Kaolin (Amerasinghe and Perry, 1975) indicate essentially the same trends as reported by Ladd (1971) and Ladd and Varallyay (1965) with the exception that for the same loading direction (i.e., TC or TE tests), the isotropically consolidated specimens had the same failure envelope (i.e., the same and c). 37 - >1 0(i 4-) U) .H 'Hl , H rzl .0 _-1 0z 4-) 9 a) W E H lY .r H a0 z_, I-t 0, o 0 - O Hk( U o0 cn 5-4HP QPr- V U' C .-4 .p 4.) k 04'H 1 :n .p 0o .P. ( U) e-r rl U -k re a P k .a P. .n 4) -H U k 44 Ok Ok H O H O H O I 4. H H W4 U) 0 D4 8rd or 0 a I I I I a4 r- Z 04 W44-) (U 0b(J fCD4U (a 4PLQ M-4 N M 0 E-4 H W t) a rl (d 0 4 i I z U)-I t.O 5-H H ) -H Id+ + C) r4 (a H H 4JW H U) 5 0X 4- t-H O W rz CA a E-1 0 p4 u H 0 (N U U) H 'O HO P: U 0 H U P U U) 0 -k 4- 3,--i . X 'l (N ") c m m a N rZ; H I H U) O H 0 .UH U) U)CA E-4 ow) ) O H4- rd4H *H 4-) rd 44 U ( P r I ) U) to H H E a 'H I4.4 'H0 Pk ( 'H4 H C, . -) X U) O z CL9 rJ CQ O 'O P" · m · rl HU) cr10 UM U1 0r4 Z o *r H O 0 O, _- HO H U) rz o0 U)04 Or r,0 H O b ) U U) O ) .,I U) H 0r "4 C rU )o U1) a z .'H 00 u) H 04 -P (U . U I i a) ,4 U) i i i im iii *, t) a)4.) tOQr OW (N A4J H 0 U)U) a a)W H Erz U) 0 UN a) O D u , 0oU) H : CN U U- U C z W *' U) toP U EH a4 0 0 P4 _l Ln O -- - --- - --- 38 --- --- Table 2 1 PREDICTION OF ANISOTROPY IN Su FROM HANSEN AND GIBSON'S EQUATION FOR PLANE STRAIN LOADING (DUNCAN AND SEED, 1966(a))'. Assuming Af = 1.0; Ko = 0.5; c = 38°; f o~~ Loading Direction a = 0 S u (a)/Cvc Su) S (a=64° ) Vertical loading(i) 64 0.37 1.0 0 0.22 0.59 -26 0.20 0.54 Inclined loading( Horizontal loading(3) ., Notes: . . . (1) i.e., Data from PSC test (2) i.e., Data from DSS (=0) (3) i.e., Data from PSE test test Table 2.2 39 INFLUENCE OF INHERENT ANISOTROPY ON MEASURED UNDRAINED SHEAR STRENGTHS OF HOMOGENEOUS CLAY FROM UUC TESTS Relative Undrained Shear Strength References Clay Vertical akobson (1955) post glacial 1.0 450 1.13+ Horizontal .02 1.05+ .05 marine clay vorslev (1960) Vienna 1.0 0.92 0.87 Hvorslev (1960) Little Belt 1.0 1.08 1.20 Duncan and Seed S.F. Bay Mud 1.0 0.86 0.81 Kaolin 1.0 0.75 0.87 itchell (1967) Kaolin 1.0 0.87 1.06 'Appolonia Resediment (1968) Boston Blue Clay 1.0 0.9 +0.03 (1966(b)) Duncan and Seed (1966(a)) 0.82+0.03 Table 2.3 40 INFLUENCE OF INHERENT ANISOTROPY ON MEASURED UNDRAINED SHEAR STRENGTHS OF NON HOMOGENEOUS CLAY FROM UUC TESTS Investigators Lo and Milligan Relative Undrained Shear Strengi I Vertical 450 Horizontal Clay Welland (Block F) 1.00 0.63 0.56 0.99 Heavily OC London Clay 1.00 0.60 -- 1.23 Varved clay from Surte, Sweden 1.00 0.82 -- 0.93 Varved clay from Step Rock Lake 1.00 0.51 0.53 1.18 (1967) Ward et al. (1965) Jakobson (1952) Eden (1955) ,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ,. Table 2.4 41 I n ak o e V ra 4 o - O W44 , H V o(o ja (N @a zo a) 4 U) M p., rU LA 0' (N *H 40 VO a0 9 W- I X- u m < t I I H r " 9 - O r.O " (N aN r( I H 0 v M (IH d oO V > H or. a M LA co co H OU rO4) 4 H* ( (N H rO r0 (e -H -H! E-4: : aH > (O ;4 Ho r- 0 N UUU) ED _ E U) U)> 0 00 00 U) C CO o O *, -- I o c gu U N E-4 U) H U) C) I0 U O *. o0o 0. UZ 1 I0: ,I 0 00 0 0: U U U) Z oU (nU) U)) P4 0 4-4 4.J U) U) o 4.. U) to a) P4 C) H g U), t ,IM o~ U I o * o o', IV)* om _ * ', I0" U) 04 pn. 0H 9: Z H 4.t a H) 40"Cr O p. · ,4 (n I 0i0 0 O O, . . * .' O- V r). Z } 3 EN _ '141a 0 44 0 0 4-4 E-i n E-4 H 01 ; 0 o _ U)O 0 X- a) o 1. - - o 0 0 0 0 t' O m a) 4 O d 0 _ _ h Co' 0 , , 0 II .U) 0 _ 0 4W a) 4) 0 WU r 00 en E-i E-i Ln ~ -oo U)QU) D (N 00 N N M o o o a) E- O 40 E- c)nU 0 H Er OsL , U) E-4 IU) H H -0 Q Ee mCN koCX m 0 LC) Ln Dr r 0 3 O 0 H rO zC4 0) O .) k H O rd ::r II OD 40 u) m Z 00 H U H W m UD z 0 0 0 a U zIU U u) o o o o o t) 00 0U) ( U U H PLU) (n N O r tP ; 4.) 0 HO -O 0 0 0 (N 0q 0 .-H0 0 0 00 0o0O o'U H O ~> n En7 'l U 0 lb 11 U. )m 43 II 0 -H O U ka H CO ) 01 H 3 H 0 O H O U a Eq 44 X O rci 0 0 H O 1>i - 144-1I H H 00 U) Oi 0 0~ - O0 I 4 - a) ,' 0G~ ,'0 00"0 U) 4-4 E- a m 0 k) P k a) 1()0 r r u 4 4) En 43 Cd C 43 U) U 0 Cas V a4- 0 c0)- U' E F' '-4 _ 0O N O U)A n - l ·-0 C EU aE 4 l',.N a 0 H > EN ,-")I N _ 4 -4 I L.r'O ~. A EU4 U] > H . .:> ,a ~. ECa o oHa Eo 0 N - _ co 0 O ',c 44 ,,4 C. -4 -'0 -4 co l Ln CD vl 4)0 __" NN'4 > x -, 1X N 0 ro > I0 ,-4 . > - I -4 N 1 ,J 9 O OO , N 4 eq ZF NN -4% 0 I o...4 oI ~. o · U" 0 Io q 4) o" o 4.40 ou o o o o N o 4u " I H) U 0 0 .:oI. n co I 0 N 4. n N 1 o U I 0-4 t, co N I3o3 HH ) a 00 m LN co 4 oN .,4 HC -.4 0 40 -4 ____t 0 -4 4 l0 to 0 U) 4 .S 0 .4 o N U o ~ : -4 4.4 --40 N O N 0 O 0 N 4 C. q* N -4 4 '' w 4 - "C I. 4 10go N: -4 to U)~~r -4 1. 44.4 1% IN I 0 0, 00,-.4 N c 0 -44 r0 I ,0 -> -0 4.4Urla, 0 C) 0 X ,4 o t o- U .4. O e Lt *T EU 4. ~O -40>4 0>4r) U)U E -4 C 4.4 A 0 .,4 E4 Plm~~~'d 2 44 N0 00 C z0 H a) r-4 H H z0 H rT: U) zz W E-4 0 o U) x -u W 0 ae H Q N 0z 0-1 I W 0 0I ON 4i 0 H U) O ,-4 r0 l O H- U U) U) O U H 0< 0 z L Lm l N L) %n C0 P4 E4 C' I W E Lf) U) U) H U4 O H Ere E-4 0 _z 0 M u] ) 0 0 0 H @ c- H CN r U) U) U C9 H 45 *ra *. 'D i 0a to : - - C O'~ I I~ C la a 0' ( _ 04 0 O - 4H 'e .0 1-4 (4 v. l N m C _ E- L L tfil 2.- r E_ 9 I_ 1.0 H - o - W W (A C t en h _ -- Vo a4 E V O O O O C4 4 I _ _ C H C) O 0 0 a 0 W , 4i -14ax (A a 41.' 0 V, to 0 9 1 e .'o o c' I 0 N V ^ ENr U o a 0 A 40 H o 0;'0 W 0) 0) N 0 4I 0w IE,4 0H 04 O 01 f14 040' %4 'H H 0 0 4-4 C ( I 0 4 8 6 C0 x (a S *4 N 0 to ru 0 14 0. C* '0 II > H> 0o 0H E1 tH EN 0 ll r 0r 1. H H H 04l~c 44 04 N 00C N _C))0H EN U 0 0 N 0 EN N 1404 r IA c H E-4 a ' 0o NEd P04 0 W ru P m - In - ' 0 44 1 E1 aw O 1-4 C) 04 '0) 4) H 0 14 r * (N 01 C .H tJ C -14 e _ IA* H U H EN~ go H0 34 0 0 .H 0 N 4.4 H .4 aC w o c 2 46 *) i IaJ "o K 4q IC 0 90 ANGLE O0 gVrtical Direc tion - ? e DEFINITION OF UNDRAINED SHEAR STRENGTH ANISOTROPY 47 FIGURE 2.1 l Q .Mc Fe I.s r 7 T'b--' ~ v t, %.UK I QU vK \ 4 n a% 0: Q Nrrr l*. IF g l~~~~b-S[[LllL~· 'tpl il 4. 0% bbI. ·- ani~~~~~~ 1!11-4 tiii'- q 0 ± s I4 t + + + bq ± C I 1l3X[ g 0 0 0C z 4· Cl)U) !a ZCL))- Z1) o jl4. I , -'--- /J w e z CD Cl) W 2 z w Ew Cfw I o0 a J LL. 0 0 .0 C z _ 4n U) C- 0 < <J w Z L 0 a - 48 wJ cnoo 0 IL Q a0 P(1Icrwfcr x O0 - I-1:z az 4 Ci M: 0 w a cL C oCO 2 :3 z CD t r oc t Cl) w .~~ X: Z ~ =: w _ CX .0 FIGURE 2.2 I a -------- a ---- am b s 404 f. (v)J O.SClc) s () ____ ?oszt(;;)3;c; V)H L a= cos2l 4=a where A= s,() su(H) L= = DAVIS-CHRISTIAN 2 /r3o /+0)n2 ngyle between and oaf vartical (1971) ELLIPTICAL ANISOTROPIC STRENGTH RELATIONSHIP 49 FIGURE 2.3 In Sitv VertIcal Directiotn o(= -s r. 2.5S 7f alf - a) DF/N/ITION OF fAILlRE PLANE ORIENTAT/ON rf circle *o-t _ I 3f from &eome try cowi=I f f in r si (26- ) Eq. 2.6 Fq. 2.7 b) STATE OF STRESS AT FAIL RE IN AN A/SOTROP/C CLAYr MODIFIED MOHR-COULOMB FAILURE CRITERIA FOR CROSS ANISOTROPIC SOIL (After Merkle,1971) FIGURE 2.4 50 Z5 SYM44. SOIL LOCATION 0 /lorthampton 0 East Windsor /3 - 12 - I REFERENCES Ladd W, fHealy, /967 East Windsor Lon9 , 1975 /./ WN= SO% - depthr 7 ft iron surfrce -- -. =60 / dA/th = -_, /12 . IV,,, frnm 10 1970 _N-\- 0.8 urfAro __, Ivx ll I i) 7kt I; from . m 1" 07 su(V) 5,, 'v) 06 OS 0.4 0.5 m 0.2 m 0.1 0 0 I /0 I I 20. 30 I 40 I I 50 60 I 70 I 80 90 P° SUMMARY OF RESULTS FROM UUC TESTS ON CONNECTICUT VALLEY VARVED CLAYS (Data from Healy, 1967; Ladd and Wissa, 1970; and Long, 1975) 51 FIGURE 2.5 U. oO B I 10 0.. S% / 0 z 0 ox I147 7/ 'I'4 /8 a 'I .41 OZ I-0 2 i Z: 0 Z ,¢~ 4- I I I co e. ( o () 0 rI I*.-~ OU) z U 0 _ot Q< O m L L~~ II ~ LL a II II Ili z cc~ U 0 0 FIGURE 2. *_ ZIG 52 0 I U) w e a. 3 o0I zj 0 _J o E 0 ~" L U.LL.. O ()Z , I- Z Iz z 'I LLL 4% - XDW(aUo)~ 53 _ FIGURE 2.7 · /. W /.0 qf (v) 0.8 0.6_ 40 0 /60 120 80 e, kN/mn A/ (4.5) At(s) al Z2 _ i/ 0 /. Af a) Af(V) 10 0Z0 "- A (cV) "0-- / o AtCH) _ .tIN rA f j -0 /I 80 I II 40 I i20 i , ktN/mZ ANISOTROPY IN qf AND Af OF FULFORD /60 2OO SOFT CLAYEY SILT MEASURED FROM CIUC TESTS ON SAMPLES WITH DIFFERENT INCLINATIONS (Data from Perry 8 Nadarajah, 54 54 1974) FIGURE 2.8 - :l I II!0) zQ tN - 0 IIi Crl- 0 '0 o 0 10 1b 1 I I 1; 0 O- U . o 0 t- c I r1i Cik IION Irs OD :kL cn C o I all. CD (0 Z 0 z ZY r% . 0 0MO.- 0 0in -J 0 w .4 0 0 I- r LJ 111 -< 1o cn coQ " 0 v< Q NoB)t k 4% 0 o k" '; o N t F C 0 n w I Z 11) I O s i U . I I I I '6 eI 681e, 55 FIGURE 2.9 \I 4 LL 0 I'Z\s NL 11 I)cn w 4 Ca z J 0 he -J tvU 411 U q'N N 4 w ti w z i% 00, C- rl% 0- z N 4 I a I I ' 'is I 11 4 t to .N t N z0 0 0wo %4 IIcn 4 (IU) tyI-.b : 0) wIM Z%' - , I I .4 e I N 4 II 0- O O llJ '4 : - -i IVI 4. > I- . I- 4 <cr cr C0 I' " " C .I '9 '.'1 a. J-io A. Ik 4s < FIGURE 2.10 i Aq0 -a c REMARK 2.6 22 28 0 0 0 C/i/c Tests I 0 45 /2.0 I 90 . l ! ._.- cc .- _ .- -_-- o = 60 psi, OCR=/.0 /0.0 I =8.5 psi v r I I. 8.0 ' &V," = 3-P pr % 1 x qf 5- =20,psi I - \~~elr _... m.mEU"°S O.C in psi -011t=1.7 OCR I . -1 I 0 ut/C T#'sts 2.0 0o EFFECT I 0 I. 20 OF &c ON THE I. i I. I. 40 ,a I 60 I I 80 MI EASUREMENT OF UNDRAIINED SHEAR STRENGTH ANISC)TROPY OF CONNECTICUT VALLEY VARVED CLAY (After Long, 1975) FIGURE 2.11 57 I- ii E L. 0-- z-J 00 CA L W) cn w I- w W cn 0-ZC cr '6- O LL - ZL -z zz icr 0 W. LL 58 FIGURE 2.12 C ('a) /.0 0.8 U Jo.-- -l (DSS) sL (V) 0.6 - ~ 0.4 a FronmTable 2.5 0 From 7able 2.6 - 0o. 0 I 0 I o , 40 I I 60 80 /0 PLAS/C/ITY INPEX,PI % O Plane Strain (b) o0 Trioial 1. 0 q (H) q () 0.u · 0 0.6 0.4 04P o.z -_ 13 From O *0 abl/e 2.7 (a *· From Table 2.6 0 FromTble 2.7(h) 0 I 0 I I I o0 80 PLA T/CITY INDEX, Pi % 20 40 1lg UNDRAINED STRENGTH RATIO VS PLASTICITY INDEX ANISOTROPIC 59 FIGURE 2.13 3. 3.1 EXPERIMENTAL PROGRAM GENERAL SCOPE AD OBJECTIVES This chapter provides a general description of varved clays from four locations, namely: East Windsor in Connecti- cut, Amherst and Northampton in Massachusetts, and Hackensack Valley in New Jersey. The similarity in the general proper- ties of these soils is discussed. The experimental program, and the details of the testing conditions used for the soil samples at each location are presented. The last portion of the chapter describes the standard testing procedures used for triaxial compression, triaxial extension, direct simple shear, plane strain compression and plane strain extension tests. 3.2 EXPERIMENTAL PROGRAM The plan of the laboratory testing program was to make a comprehensive study of the anisotropic behavior of the four varved clays. Additional test results for the Northampton and and Hackensack Valley varved clays are reported in Lacasse et al. (1972) and Saxena et al. (1974). Tables 3.1(a) and 3.1 (b) present a summary of the experimental program. consisted 1. of: A series of unconsolidated-undrained triaxial 60 It compression (UUC) tests run with different orientations of the varves; 2. A series of isotropically consolidated-undrained triaxial compression (CIUC) tests with pore pressure measurement run with different orientations of varves and at varying 3. A series of K OCR; consolidated-undrained triaxial compression (CK UC) tests with pore pressure 0 measurement at varying OCR; 4. A series of isotropically consolidated-undrained triaxial extension (CIUE) tests with pore pressure measurement run on vertical and horizontal samples at varying OCR; 5. A series of K o consolidated-undrained triaxial extension (CKoUE) tests with pore pressure measurement at varying OCR; 6. A series of Ko consolidated-undrained direct simple shear (CKoUDSS) 7. tests at varying OCR; One special Ko consolidated-undrained direct simple shear test run on a normally consolidated sample where the normal and shear stresses were applied during consolidation before the sample was sheared by increasing the horizontal shear stress to simulate plane strain compression (CKoUDSS 8. (C) test); One special Ko consolidated-undrained direct 61 simple shear test run on a normally consolidated sample where the normal and shear stresses were applied during consolidation before the sample was sheared by reversing the direction of the horizontal shear stress to simulate plane strain extension (CKoUDSS (E) test); 9. One K consolidated plane strain compression (CKoUPSC) test run on a normally consolidated sample from Northampton; 10. Two Ko consolidated undrained plane strain (CK0 UPSE) tests run on a normally consolidated sample from Northampton; 11. A series of consolidated drained direct shear (CDDS) tests at different OCR on Northampton varved clay; 12. Two isotropically consolidated drained triaxial unloading (CID (U)) tests on Northampton varved clay. Both SHANSEP and RECOMPRESSION* methods of consolidation were used for items 3 and 5. The locations and the testing condi- tions of soil samples are presented in Section 3.3. Chapter 4 will present the investigation of the normalized behavior of these soils, and a comparison of their NSP. *RECOMPRESSION--the method of consolidation whereby the sample is consolidated at the desired OCR with a vertical consolidation stress that is less than the in situ maximum past pressure. 62 The testing program included CKoUC, CKoUE, and CKoUDSS tests on varved clays from East Windsor, Amherst, Northampton, and Hackensack Valley. NC CIUE test vertical samples and NC CIUC test samples with different inclinations, of East Windsor and Amherst varved clays, were also tested to compare their NSP. All samples were consolidated according to the SHANSEP approach. The effect of stress system on the NSP, obtained via the SHANSEP approach, of Connecticut Valley varved clays is presented in Chapter 5. 1. This includes: The effect of initial shear stress (i.e., isotropic versus K consolidation); 2. The effect of the intermediate principal stress; 3. The effect of testing method for shearing parallel to the varves. CK UC and CIUC tests on vertical samples which had OCR's of 1,2, and 4 were run to study the effect of initial shear stress on NSP for vertical loading. For horizontal loading, CK UE and CIUE tests were run on vertical samples with OCR's of 1, 2, and 4. CIUC tests on vertical samples, and CIUE tests on horizontal samples, at OCR's of 1, 2, and 4, were run to study the effect of the magnitude of the intermediate principal stress for vertical loading. Similarly, CIUC tests on horizontal samples and CIUE tests on vertical samples at OCR's of 1,2, and 4, were performed to study the effect of 2 on NSP for horizontal loading. Results from CKoUPSC and CK UPSE tests (Lacasse et al., 1972) were also used to o 63 compare with data from CK oUC and CKo UE tests for the investigation of the effect of 2' The special CK UDSS (C) and CK UDSS (E) tests on inclined samples from East Windsor also O served this purpose. and CK UDSS CIUC tests on inclined samples (8=45), tests on vertical samples at varying OCR, were performed to study the effect of testing method for shearing parallel to the varves. Test results from drained direct shear tests on samples from Northampton (Lacasse et al., 1972) were also used for this purpose. Chapter 6 will study the effect of "sample disturbance" on NSP. UUC tests on samples with different inclinations, CIUC tests on samples with different inclinations consolidated tests on verby the RECOMPRESSION method and CK 0UC and CK oUE 0 tical samples consolidated by the RECOMPRESSION method were performed for this study. The NSP from these tests are then compared with the NSP from SHANSEP samples which have the same OCR. Interpretation of the anisotropic undrained strength behavior of varved clays, which is based upon the results from Chapter 5, is presented in Chapter 7, while Chapter 8 provides the "best estimates" of soil parameters for use in the design of structures on varved clays. 3.3 DESCRIPTION OF VARIOUS CLAYS This section provides a general description of the soil samples and their index properties. 64 Details of the geological formation of the Connecticut Valley varved clays are presented in Ladd and Wissa (1970); the geological formation of the Hackensack Valley varved clay is discussed in Saxena et al., (1974). Briefly, the Connecticut Valley varved clays were deposited in glacial Lake Hitchcock during the late Pleistocene time. The bedrock of this area was covered by a widespread but discontinuous blanket of till. After deposition of the varved clays, glacial Lake Hitchcock was drained when the natural dam at Rocky Hill, Connecticut breached. As a result, the varved clays along the Connecticut River were then deeply eroded. The eroded surface was subsequently covered by post glacial sand deposits. The upper present-day surface of the varved clay is thus not necessarily the same as its original surface under Lake Hitchcock. The varve thicknesses vary typically from 1/2 to 2 1/2 inch. The thickness often de- creases with increasing elevation because of the disappearance of the glaciers with time. The Hackensack Valley varved clay was obtained from the Hackensack Meadows. It is a tidal marsh occupying the area of a glacial lake formed by the obstruction of a preglacial valley with glacial drift in the vicinity of Perth Amboy. In recent times, extensive areas of the meadows have been covered with uncontrolled fill varying in thickness from 2 to 12 ft. 65 3.2.1 East Windsor Varved Clay Two undisturbed one cubic foot block samples of East Windsor varved clay from the same depth, were provided by Prof. R.P. Long of the University of Connecticut. They were ob- tained from a clay pit located off Route 5 and owned by the Kelsey-Ferguson Brick Co. in East Windsor, Connecticut. The clay is greyish in color and the varves show a gradual transition in grain size from top to bottom; but upon drying, the "clay" and "silt" layer can be easily distinguished by their dark and light colors, respectively. The thickness of these layers generally varies from 1/16 in. to 3/16 in. The block samples were taken from the clay pit at a depth of about 11 ft. Five ft of medium sand and six ft of brown varved clay overlie these samples. They have an esti- mated effective overburden pressure of 0.6 kg/cm 2. The samples generally had very uniform properties, based on torvane strengths and natural bulk water contents. Only portions of these samples which had the same torvane strength and moisture content were used for testing. Table 3.2 shows the index and the engineering properties of the East Windsor varved clay. plasticity chart According to Casagrande's with the basis of limited data, the clay por- tion can be classified as CH material and the silt portion can be classified as ML material. Fig. 3.1 shows results from three standard consolidation tests on samples from these two blocks. The strains at the end of primary consolidation, 66 determined by the %'t~method, are used in the plot of the vertical strain versus log avc A small variation in the values of the maximum past pressure (avm) and the virgin compression vm ratio (CR) is noted in these tests. clay is 2.4 kg/cm 2. The average avm of this The in situ OCR is therefore about four. Table 3.3 gives the details of the testing conditions and the types of tests performed on the samples. 3.2.2 Amherst Varved Clay Under sponsorship of the Massachusetts Department of Public Works and the US Department of Transportation Federal Highway Administration for research on varved clays, the Department of Civil Engineering at MIT obtained 5 in. diameter undisturbed samples from a boring near the Route 116 by-pass and North Hadley Road at the University of Massachusetts, Amherst. These samples were obtained by using an Osterberg type fixed piston sampler. Field vane tests using the Geonor apparatus were also run adjacent to the boring. The clay is generally grayish and brown in color, and the varve thickness varies from 1/2 in. to 1 in. The varve thicknesses of the Amherst varved clay are larger than those from East Windsor. Figure 3.2 shows the soil profile, Atter- berg limits and compressibility data. The soil profile con- sists of a thick deposit of varved clay overlain by 3 ft of clayey sand. The bulk moisture content and plasticity index first increase and then decrease with depth (below El. 95), 67 but such changes are relatively small indicating a fairly uniform deposit of varved clay. The bulk moisture content is also larger than the bulk liquid limit, indicating that the soil may be somewhat sensitive. Figure 3.3 shows the general soil profile, stress history, and undrained shear strength from triaxial UUC and field vane tests. The stress history shows that the soil is overconsoli- dated at all depths. of the maximum It is presumed that the increasing values past pressure prior disiccation (avm) above El. 110 is due to (Ladd, 1975). slightly overconsolidated. Below El. 110, the soil is This resulted from a lowering of the ground water table and/or erosion of the overburden. The Geonor field vane strengths below the crust are almost constant with depth at 700 + 100 psf; the sensitivity from the field vane test is about 7 above El. 100, and 5 to 6 below that depth. Triaxial UUC tests yield strengths fairly close to those measured with the field vane in the upper portion of the clay, whereas below El. 110 they are significantly lower. Table 3.4 shows the details of the testing conditions and testing program. 3.2.3 Northampton Varved Clay Four borings, B through B4, were made at several loca- tions near the intersection of I91 and Route 9 in Northampton, Massachusetts (Ladd and Wissa, 1970). Three in. diameter undisturbed samples were obtained from borings B1 and B2 in 68 1967 and 5 in. diameter undisturbed Osterberg type samples were obtained from Borings B3 and B4 in 1970. Field vane tests using the Geonor apparatus were run adjacent to Boring B3 and B4. Soil samples from Borings B3 and B4 were used for consoli- dated - undrained strength tests. See Ladd and Wissa (1970) for further details. Figure 3.4 shows the soil profile, Atterberg limits, and virgin compression ratios from the borings. The soil profile generally consists of a thick deposit of varved clay which is covered by medium sand. The clay is grayish or gray brown in color and has typical varve thicknesses of one-half to one inch. The Atterberg limits of the clay and silt portions of the Northampton varved clay show no significant difference from those of the Amherst and East Windsor varved clays. Values of the virgin compression ratio range from 0.2 to 0.4. The upper values are larger than those from Amherst and East Windsor. The varved clay deposit at Northampton is not as uniform as that at Amherst. Figure 3.5 shows stress history and undrained shear strength data from triaxial UUC, unconfined compression, and field vane tests. The stress history from the "good quality" undisturbed sample at Boring B3 and B4 shows that soil is overconsolidated at all depths. The stress history from Bor- ings B1 and B2 is not as reliable because the samples were more disturbed. The results from the Geonor field vane tests indicate that the clay is medium to stiff and that the strength 69 increases with depth from 1000 psf at El. 90 to 1700 psf at El. 50. Undrained strength data from unconfined compression and triaxial UUC tests on vertical samples are significantly lower, exhibit appreciable scatter and show no consistent trend with depth. This occurred in spite of the fact that the tests were run on samples from 5 in. diameter fixed piston samples. Table 3.5 shows the testing program of Northamp- ton varved clay. Other experimental results were also reported in Lacasse et al. (1972). 3.3.4 Hackensack Valley Varved Clay Five in. diameter Osterberg type samples of varved clay were obtained from the Hackensack Valley at Sacaucus, New Jersey in cooperation with the Port Authority of New York and New Jersey. The boring was located immediately to the south- west of the Palisades in the township of Secaucus (see Saxena et al., 1974). Figure 3.6 shows the general soil profile, Atterberg limits, the stress history, and the values of the virgin compression ratio. The soil profile consists of fill, peat, sand, and silty clay overlying about 35 ft of varved clay. The varved clay is red-brown in color. nesses vary widely. The varve thick- They are about 3/8 in. at shallow depths and about 1 in. below El. -40. Though the bulk natural mois- ture content is somewhat lower, the bulk Atterberg limits and the values of the virgin compression ratio are generally 70 similar to those for the Connecticut Valley varved clays, at least for samples between El. -35 to 50 ftwhich were used for the consolidated-undrained strength tests. The stress history at this site shows that the clay is overconsolidated at all depths. The causes of the overconsoli- dation are mostly due to desiccation for soil above El. -40 and to the lowering of the ground water table for soil below El. -40. Table 3.6 shows the experimental program for the Hackensack Valley varved clay. 3.4 SUMPARY OF SOIL PROPERTIES The following is the summary of the soil properties of Northampton, Amherst, East Windsor, and Hackensack Valley varved clays. 1. The soil profiles of Amherst, Northampton and Hackensack Valley have thick deposits of varved clay, although the varve thicknesses varied. 2. At Amherst, the deposit was quite uniform, as were the thicknesses of the clay and silt layers. On the other hand, the deposits at Northampton and Hackensack Valley were more variable. 3. The varve thicknesses of samples from Amherst, Northampton, and East Windsor used in the testing program (Tables 3.3 to 3.6) are different. 71 Northampton and Amherst samples have about the same varve thicknesses. East Windsor samples have the smallest varve thickness. The varve thickness of Hackensack Valley samples are between those from Amherst and East Windsor. 4. Despite the difference in varve thicknesses, the samples used in the undrained strength tests from East Windsor, Amherst, Northampton, and Hackensack Valley have essnetially the same bulk Atterberg limits and virgin recompression ratio (see the summary in Table 3.7). The Atterberg limits of the individual clay and silt portions of the Connecticut Valley varved clays (no data from Hackensack Valley varved clay) are also essentially the same. However, the natural moisture contents (listed below) of the Hackensack Valley varved clay are significantly different from those of the Connecticut Valley varved clays. Soil Location 3.5 W (%) vm (k/cm 2 ) M Amherst 63+4 2.0+0.5 Northampton 59+3 3.0+0.5 East Windsor 57+2 2.4+0.2 Hackensack Valley 48+2 2.5+0.1 GENERAL 'ESTING PROCEDURE All tests were performed at MIT using the general test 72 procedures described below. 3.5.1 Consolidated Undrained Triaxial Tests Triaxial Compression Test All triaxial compression tests were performed with Geo- measurement cells. consolidation. Only bottom drainage was allowed during One of the two drainage lines leading from the bottom pedestal at the base of the triaxial cell was attached to a burette for measuring the volume change. An electrical pressure transducer was attached to the other drainage line for the measurement of pore pressure during shear. The con- fining pressure, applied to the triaxial cell water, and the back pressure were obtained from adjustable mercury columns (Bishop and Henkel, 1962). After samples were cut to the de- sired varved inclination, they were tested according to the standard triaxial testing procedure presented in Ladd and Varallyay (1965). The experimental program includes both isotropic and Ko consolidation. For Ko consolidation, the axial consolidation stress was applied to the samples with small load increments by using dead weight. The value of Kc , the ratio of the ef- fective horizontal consolidation stress (hc) tive vertical consolidation stress (vc ), to the effec- was adjusted with each load increment to obtain essentially one-dimensional strain. Since an approximate relationship between Ko and OCR was known in advance, Ko consolidation was closely followed in most load steps. Vertical filter strips are used for 73 accelerating the drainage during consolidation and equalizing the pore pressure during shear. The samples consolidated via the SHANSEP approach were loaded in steps to a stress greater than about 1.2 to 2 times the in situ maximum past pressure (vm). For testing samples at an OCR greater than one, the samples were unloaded to the desired OCR. The RECOMPRESSION samples were loaded in steps to the vertical stress at the desired OCR (--). At the final consolidation stress, two vc days were used for normally consolidated SHANSEP samples to allow a reasonable amount of secondary compression, and one day was used for OC SHANSEP and RECOMPRESSION samples. A back pressure of 2.0 kg/cm 2 was used for all tests. All but two of the overconsolidated SHANSEP CKoU test samples were consolidated to a maximum vertical effective 2 stress of 3.6 kg/cm before they were unloaded. The vertical effective stress was increased in the following steps: 0.5 kg/cm 2 (isotropic), 0.95, 1.6, 2.0, 2.3, 2.75, 3.23 and 3.6. The vertical effective stress was then rebounded to 1.8 kg/cm 2 in two steps and 0.9 kg/cm 2 in one step to obtain samples which had OCR's of 2 and 4, respectively. The other two OC CKoUC test samples (OCR of four) were consolidated to 4.0 kg/cm before being unloaded to 1.0 kg/cm 2 All NC SHANSEP samples used for CIU (CIUC and CIUE) tests were consolidated to a maximum consolidation pressure of 4.0 kg/cm2. The load steps were 0.3, 0.75, 1.5, 2.5 and 4.0 kg/cm 2 74 RECOMPRESSION samples from East Windsor were isotropically consolidated to the overburden pressure of 0.6 kg/cm 2 two steps to obtain samples with an OCR of four. in Samples with an OCR of two were anisotropically consolidated to a vertical effective stress of 1.2 kg/cm2 in three steps. Wykeham-Ferrance loading frames wereused to produce controlled rates of strain during shear. A strain .rate of 0.7%/hr was used for SHANSEP samples, and 0.35%/hr for RECOMPRESSION samples. The samples were loaded (i.e., axial stress increased) in compression tests and a proving ring was used for measuring the load. Readings of elapsed time, pore pressure, sample length, and the vertical load from the proving ring were obtained from a data aquisition system with less frequent visual checks. The piston friction correction was obtained by measuring the friction force required to move the piston through water in a triaxial cell at the strain rate and cell pressure corresponding to the testing condition. The correction was made by subtracting this friction force from the total measured axial force. A filter paper correction was applied in CKoUC tests according to the procedure outlined in Ladd and Varallyay (1965). Triaxial Extension Test The testing procedure for TE test is different from that for TC test in two aspects, as follows: 75 1. During sample set-up: the filter strip paper is wrapped spirally around the sample instead of being placed vertically as in the TC test. 2. Thus, there is no filter paper correction. During shear: the samples were unloaded (i.e., axial stress decreased) in TE tests. Also, suitable methods for connecting the top cap to the loading piston and the loading piston to the proving ring are needed. Figure 3.7 shows a schematic diagram of the essential elements in the TE test, including the connections between the loading piston and the top cap, and between the loading piston and the proving ring. Two piston pins (1) are inserted into the chamber (2) in the top cap (3) for connecting the loading piston (4) to the top cap. After lowering the load- ing piston until it touches the ball bearing (5), the connection between the top cap and the piston was then made by rotating the pin across the slot. As there is a small clearance between these pins and the top cap, this arrangement will not cause a torsional force to be applied to the top of the sample. The proving ring and the loading piston were connected by two pins (6) and two cross bars (7). These two pins were first put through the holes located in the piston block (8) and the proving ring head before inserting the cross bars. Because the diameter of these pins is smaller than the holes in the cross bars, proving ring head, and the piston block, the connection is very flexible. Consequently, any small deviation in alignment of the proving ring, loading piston 76 and top cap is not very important. For CKoUE and CIUE tests, the load steps, the back pressure, the rate of shearing, and the time allowing for final load increment during consolidation were identical to those used for TC tests. 3.5.2 Testing Problems with Consolidated Undrained Triaxial Tests Due to the layered nature of varved clays, disturbance due to trimming and setting up the sample, expecially with TE tests, can severly affect the undrained shear strength. Chapter 6 will discuss the effect of disturbance due to trimming which causes separation of silt and clay portions in horizontal and inclined samples. This section will present test data illustrating the importance at the details of testing on the undrained shear strength (su=qf) when disturbance during setting up a TE test sample introduces a plane of weakness. In the TE test, the process of connecting the loading piston to the top cap can introduce sample disturbance. Table 3.8 shows qf data from NC and OC samples from Amherst, Northampton, and East Windsor, using two different testing procedures. Upon using the "new" testing procedure described in Section 3.5.1, qf/'vc (Table 3.7 (a)) from OC (OCR=4) samples from Amherst and East Windsor are essentially identical (in fact, it will be shown in Chapter 4 that NSP from Amherst, Northampton, and East Windsor are identical). 77 Thus, the larger qf/vc (an increase of 30%) of NC East Windsor clay compared to those for NC Amherst and Northampton (using "previous" testing procedure) was due to the difference in the testing procedures. In the "previous" method, the tests (NC Amherst and Northampton samples) were performed in a cell where the loading piston was screwed into the top cap after the samples had been set up, and that probably caused a slight separation between one or more varves at the top of the specimen and hence introduced planes of weakness. This in turn probably caused the decrease in qf for NC Amherst and Northampton samples. The fact that necking occurred at the top of these samples instead of at the middle of the sample as observed in the East Windsor specimen seems to support this hypothesis. 3.5.3 The Direct Simple Shear Test All tests were performed with a Geonor Model 4 direct simple shear device. Description of the equipment and the step by step testing procedures for CKoU tests are outlined in detail in Ladd and EdgerS(1972) and Saxena et al. (1974). In this test, a cylindrical sample 8 cm in diameter and approximately two cm high is confined in a wire-reinforced rubber membrane. This allows vertical deformations and hori- zontal shear movement with little or no change in diameter. During consolidation, there is very little lateral strain so that Ko consolidation is closely approximated. The con- solidation process is the same as that of an ordinary consolidation test wherein a lever arm is used. 78 The direct simple shear device is capable of applying an instantaneous load which is achieved by locking the lever arm, putting on.a load increment and then releasing the level arm. The SHANSEP samples were first loaded in steps to stresses greater than about 1.5 to 2. times the in situ maximum past pressure for the normally consolidated samples. For the overconsolidated samples, ths specimens were then unloaded to obtain the desired overconsolidation ratio. at the last load increment A period of two days was allowed for normally consolidated samples, and one day was allowed for overconsolidated samples. Shearing was achieved by applying a horizontal shear force parallel to the top of the specimen. The sample height during shear was kept constant by a screw-controlled loading mechanism to cause shearing under constant volume conditions. This was done by regulating the vertical stress so that the dial gage reading for vertical deformation remains constant, after allowing for the compression or expansion of the porous stones and the top and bottom caps. The state.of stress dur- ing shear can be considered to be close to a plane strain condition (Ladd and Edgers, 1972). The rate of shear for the tests was 5.5%/hr. The special test procedures used for testing inclined samples are described in Section 5.3.4. 3.5.4 The Plane Strain Tests This section provides a very brief description of the 79 MIT plane strain device and the testing procedure used with the Northampton varved clay. Details of the device and testing procedure are given in Bovee and Ladd (1970). Two types of plane strain tests were performed, namely: Ko consolidated undrained plane strain compression (CKoUPSC) tests and plane strain extension (CK UPSE) tests on vertical samples. The CKoUPSC test sample was sheared by increasing the vertical stress (i.e., alf = avf), while the CKoUPSE test sample was sheared by decreasing the vertical stress. Figure 3.8 shows a simplified diagram of the specimen and the loading systems in the MIT plane strain device. The sample can be loaded both vertically and horizontally (the latter only used during consolidation for the strain controlled test). With the vertical loading system, during consolidation a vertical load is applied by a hanger placed with dead weights on the loading piston. During strained controlled shear, a load cell is placed above the hanger and a variable speed load frame is used to apply the vertical load. For the horizontal loading system, a cell pressure (supplied by the self compensating mercury pot system) transmitted to the sample via a cell membrane is used for the purposes of: (1) Maintaining Ko consolidation. Movable side platens located within water-filled chambers enclosed by the cell membranes and the side assembly plates are also used for restricting the horizontal deformation during consolidation. 80 (2) Applying (ah increments to the sample during shear in stress controlled PS tests (not used for this study). The pore pressures are measured from the transducer at the bottom of the specimen. The back end platen (Fig. 3.8) has a flush diaphram transducer for measuring the horizontal normal shear at that height. Testing Procedure The test specimen is 3.5 in by 3.5 in. by 1.4 in. After trimming, the entire specimen (after installing filter paper, overlapping for CKoUPSE test and continuous for CKoUPSC test) is enclosed in a 0.015 in thick membrane. A watertight seal is maintained by compression of latex membranes and an o-ring between the platens located at the top and bottom of the specimen and the piston block or the base plate. Prior to each consolidation increment (dead weight for the vertical stress and cell pressure for the horizontal stress), the side platens are brought into contact with the end platens (Fig. 3.8) for restricting the horizontal deformation. During consolidation, adjustment of the cell pressure is required to insure that the volume change resulting from axial movement of the piston times the sample area equals the volume change recorded on the volume change device. At the later stages of consolidation in each load increment, the side platens are withdrawn. After final consolidation, the CKoUPSC test sample is vertically loaded by forcing the loading piston against 81 the load cell. The CKoUPSE sample is sheared by pulling up a loading piston and load cell. The back pressure in the test was 2.0 kg/cm . of shearing was 0.7%/hr. The rate The corrections for filter paper (PSC only) and membrane resistance are given in Bovee and Ladd (1970). 82 SUMMARY OF THE EXPERIMENTAL PROGRAM Type of Test UUC (1) 8 Method(3 ) Consolidation Consolidation 4 0, 45, 90 E 0, 90 E 1,2,4,20 S 45 E 1,4,20 S 45 A 1 S 0 H 1 S E 4 R CIUC 0,45, CKoUC 0 _IUE 90 (1) -- 0 E- 1,2,4 S 0 A 1,2,4 S 0 H 1 S 0 E 2,4 R 0 A 1,6 R 0, 90 E 1,2,4 S 0, 90 A 1 S E 4 R 90 Notes: Soil(2) Location ! = angle between the varves and the in situ horizontal direction. (2) E = East Windsor, A = Amherst, H = Hackensack. (3) S = SHANSEP R = RECOMPRESSION Table 3.1(a) 83 SUMMARY OF THE EXPERIMENTAL PROGRAM Type of Soil 0 Test Method (1) of Consolidation e Location 0 E 1,4 S A 2,4 S E 2,4 R A 1.6 R 0 E 1,2,4 S 0 A S 0 N 1,3,6 1,2,4,8 0 H 1,2,4 S 0 A 1.6 R CKoUDSS (C) 45 E 1 S CK UDSS(E) 45 E 1 S CK UPSC 0 N 1 CK UPSE o 0 N 1 CDDS 0 CK UE o CK UDSS o (3) OCR S I S I 0 N 1,1.8,3,5 Notes: S,R u _ (1) E= East Windsor; A = Amherst; N = Northampton; H= Hackensack (2) S = SHANSEP; R = RECOMPRESSION Table 3.1(b) 84 I SUMMARY OF INDEX PROPERTIES AND ENGINEERING PROPERTIES OF EAST WINDSOR VARVED CLAY Physical Properties: Description Natural Water Content Bulk Sample (%) 55 - 60 Clay Layer Silt Layer 63 45 Liquid Limit (%) 50.0 64.5 43.6 Plastic Limit (%) 28.9 31.4 30.5 Plasticity Index (%) 21.1 33.1 13.1 2.8 Specific Gravity Total Density 104 - 105 -- -- . . (pcf) Engineering Properties: a vm = 2.4 + 0.1 kg/cm CR = 0.20 + 0.01 RR = 0.035 + 0.003 2 qf from UUC test = 0.37 TSF (vertical sample) Su from Torvane = 0.35 + 0.02 TSF Table 3.2 85 LABORATORY TESTING PROGRAM OF EAST WINDSOR VARVED CLAY ( = varve inclination) Type of Test Test No. to EUCEUC-3 UUC 00 OCR Method of Consolidation 4 -- '1,2,4,20 SHANSEP 0,45,90 EIC-i-1 to EIC-I-4 0 EIC-2-1 to EIC-2-3 CIUC 45 1,4,20 EIC-3-1 to EIC-3-1 to EIC-3-4 90 1,2,4,20 EIE--1 to EIE-1-3 0 1,2,4 SHANSEP CIUE EIE-3-1 to EIE-3-3 EIE-3-3 o90 to EKC-5 EKE-1 t 1,2,4 CK UC 0 1,2,4 SHANSEP CK UE 0 1,4 SHANSEP CKoUDSS o 0 1,4,7.38 SHANSEP o EKE-1 to EKE-3 o EDS-1 EDS-3to ESDS-1 ESDS-2 CKoUDSS(C) CK UDSS(E) ERTC-1-1 ERIC-2-1 ERIC-3-1 45 45 1 1 0 4 CIUC 45 90 ERIE-1-1 CIUE 0 4 ERKC-1 CK UC 0 2 ERKE-1 CK UE 0 2 to 2,4 SHANSEP 4 ERIC-3-2 RECOMPRESSION Table 3.3 86 LABORATORY TESTING PROGRAM OF AMHERST VARVED CLAY Test No. ACK- to(b) Type of Test OCR Method of Consolidation CKUC 0 1,2,4 SHANSEP CK o UE 0 2,4 SHANSEP CK o UDSS 0 1,3,6 SHANSEP 1 SHANSEP AKE-1 to AKEAKE-2to ADS-1 to ADS-4 ADS-4 AIC-1-1 0 AIC-2-1 CIUC 45 AIC-3-1 90 AIE-1-1 AIE-3-1 CUE 0 1 0 1 ,9 ARKC-1 CK UC 0 ARDS-1 CK UDSS 0 ~ = varve SHANSEP 1 0 1.6 RECOMPRESSION 0 1.7 RECOMPRESSION . inclination Table 3.4 87 LABORATORY TESTING PROGRAM OF NORTHAMPTON VARVED CLAY Test No. NKC-1 and NKC-2 NDS-1 to NDS-8 NCD-1 to NCD-6 Type of Test OCR Method of Consolidation SHANSEP CK0 UC 0 1 CK UDSS 0 1,2,4,8 SHANSEP 0 1,1.83,3 SHANSEP CDSS NPC-1 CK .oUPSC 0 1 SHANSEP NPE-1 and NPE-2 CK UPSE 0 1 SHANSEP = varve inclination Table 3.5 88 LABORATORY TESTING PROGRAM OF HACKENSACK VALLEY VARVED CLAY Test No. Type of OCR Method of Consolidation HKC-1 CKoUC 0 1 SHANSEP HIC-1 CIUC 0 1 SHANSEP HDS-1 to HDS-4 CKoUDSS 0 1,1.98,4.12 SHANSEP l I , e = varve . I inclination. Table 3.6 89 SUMMARY OF THE INDEX PROPERTIES OF VARVED CLAY SAMPLES FROM AMHERST, EAST WINDSOR, NORTHAMPTON, AND HACKENSACK VALLEY Typical Varved . 1/2 to 1 inch. Thickness . - _ ---- WL Wp PI Bulk 53 + 4 26 + 4 27 + 8 Clay* 70 + 5 35 + 5 35 + 10 ISilt* 40 + 4 26 _I_ ; . _-_ _ + 4 14 + 8 _ CR = 0.2 to 0.3 *Average of available data where the strength tests were made. Table 3.7 90 COMPARISON OF THE UNDRAINED SHEAR STRENGTHS FROM THE CK UE TESTS FROM DIFFERENT TESTING PROCEDURES (a) Stregnth Data from New Testing Procedure: Soil Location Amherst L East Windsor Uvm (L) | OCR qf/Cvc 1.71 4 0.63 1.50 4 0.65 t (b) Strength Data from Previous and New Testing Procedure( 3) at OCR = 1.0 L vm Soil Location a Amherst 1.76 Northampton East Windsor Note: Testing Procedure Previous q f vc 0.16(1) Remark From Ladd (1975) 1.1 + 0.1C Previous 0.15 + 0.01(1 Ladd (1975) 1.50 Now 0.21(2) 2 Tests (1) Failure at the top of the sample by necking. (2) Failure at the middle of the sample by necking across the varve. (3) Described in Section 3.5.2. Table 3.8 91 0 5' /0 - - K4 A LU VYMA d CR= 0.20 f O.0/ S4 8 £6.8 O 2s ! , I1 RR =O.035+ O.003 5S.I I 0.5L /.0 VERTICAL CONOL IDA710N, ~iI J0 vc, 7TSF 2.,.c /0.O I.O 0.75 Data for loadiny c, determined 6y Vr nmethod X. ri o a0.s o 0 D~eon / I' oodi ng 0Fisf SI A U v 0 · 0.I 0.f . · zO r 50 · ---- /0.0 .0.0 V6RTICAL CONSOLIDATION STRESS, 7SF RESULTS OF CONSOLIDATION TESTS ON EAST WINDSOR 92 VARVED CLAY FIGURE 3.1 m,l G.$. El. M£l 13 water ontnt 40 0 Bulk /JS! /2S p X 0.2 I t - OI I X Grey ! I-- mnedium i- /arved 0.J . * - loay 0.1 , Sitf A StifC, o w. WN 6rey -- CR, RR 80 W C/ayey Sand Vorved C/oy ./Q M.) i 1 soft i -- I '4S - Jome .stones A -4_ -44 X roS - xeemr I more si/ty lal i I 6rey /00 - Vorved 0--- !LI--*6 --- :- i i I I I Cloy very oft stones x - --- 95S Ii- Brown cI Varved Cloy 8s Pq{- f I medium soft t .... 11 . RR CR I min. lwx. , A I 7S ._ _ I O- --- SOIL PROFILE, ATTERBERG LIMITS, RECOMPRESSION RATIO, AND VIRGIN COMPRESSION RATIO OF AMHERST VARVED CLAY 93 FIGURE 3.2 a w r I 0 I zw r. 1- C,) w z z: r -r z I IrCl) ct r I- ,) w -J 0 -J 94 FIGURE 3.3 so CR B/fB ICu . -B4. ' '' . 2 Sond 83 . ,-. 0o0nd. iXlTER CO6NT£7 .20 C0 40 % A0 COMPRES'SI/O /00 RATIO w n2 0 v - _~_._ . __ . --- 4 T i'slty Kssli Sand Boring 83 N.-i Grey 90 Grey 9 Grey I- Vared o80F Q- ok- v Vurved ! 70o c>_0 L-111- Vrwd I -o -4 8 estr C/oy clay v I I J1 I' -.4 60- F. . l 4J -4 I!- I I C/oay rI 0 L4j i Sand Cloy C/fw IC7,,y Cloy Bulk x ;-, Silt A r C/ly ·* E. (ft) 8/l 2 ,o. Sand L w 0- R .S. . . nT/ 'A. V tvwn 40O iV I 0 Grey K I I I I 6rey- - 85 84 /39 1/24 // *max min. OFDOMETER t CRSC o A 0 o CR plotted SUMMARY OF ATTERBERG LIMITS AND COMPRESSIBILITY OF NORTHAMPTON VARVED CLAY (From Ladd & Wissa, 1970) 95 FIGURE 3.4 , VI 0 I% Mi f%b Cl) WO aw crE 0 z 0O Eof, F : Z La O LL. 0oa o 0 4 In oc D _;z L wz aQ , _j 0 Sn> en I en g > 'Cla> -4. It .6i a lb' iU L4J 1 I' 44 "I~4 e11ZIQ l (7S'W J 'OIl 96 VA373 FIGURE 3.5 w cK w 3 z 0D w lO C) (0 o 0Z.¢ Or c aC E m -o L. oLL O z 0I 0o cn z> 0 0 Er 1%~~~ ~ ~~~~~ '9 ej 97 C')a (63. FGR FIURE 3.6 I- 0 C k W w x- h'W -z I... -I z w w w .I CT zw Cl) en w 0 C \3 1iS 98 :f w m FIGURE 3.7 a., epi-ton) VERTi/CAL CV LOADING TrzAA rend Ploten) (From Ce/I Membrorac) HOR/ZONTAL L OAD/IN& SYSTEM DIAGRAMATIC DRAWING OF PLANE STRAIN SAMPLE AND LOADING SYSTEMS 99 FIGURE 3.8 4. COMPARISON OF NORMALIZED BEHAVIOR OF DIFFERENT VARVED CLAYS 4.1 INTRODUCTION AND BACKGROUND Normalized soil parameters (NSP) such as qf/avc, Af, Eu/vc ¢ and c/Evm, obtained using the SHANSEP approach (Ladd and Foott, 1974) have been used extensively for.studying the stressstrain-strength properties of the Connecticut Valley varved clays(Ladd, 1975). The objectives of this chapter are: (1) to demonstrate experimentally whether or not varved clays, particularly those from Connecticut Valley, exhibit normalized behavior; and (2) to compare the NSP of varved clays from several locations. The SHANSEP approach uses a maximum laboratory consolidation stress that is at least about 1.5 to 2.0 times the in situ maximum past pressure ( vm). Overconsolidated samples are ob- tained by unloading from this maximum stress. Thus, in general, the SHANSEP samples which have the same laboratory OCR can have different magnitudes of.the laboratory maximum past pressure [a (L)], and thus, the maximum past pressure ratio, (MPPR), vm a vm (L) . At a given laboratory OCR, a difference in the MPPR of vm SHANSEP samples can result from differences in the magnitude of vm (L) for samples with the same avm and/or from differences of am Vm of the samples used for testing. 100 If a soil exhibits normalized behavior, then at a given laboratory OCR and for the same stress system (both during consolidation and shear), the MPPR will not have a significant Thus, plots of NSP versus OCR obtained for a Ovm(L) . Since the given stress system should be independent of vm soil structure (Lambe, 1958) prior to shear can change with effect on NSP. the magnitude of the laboratory applied consolidation stress, SHANSEP samples at a given OCR, but having different MPPR, may have different soil structure . For a soil that exhibits near- perfect normalized behavior, changes in soil structure with MPPR are minimal, and NSP from SHANSEP samples which are consolidated and sheared with a stress system similar to that of the in situ soil, should represent the in situ soil parameters. The experiment program shown in Table 4.1 is divided into two parts according to the objectives of the investigation , as follows: (1) Does varvedclayfran a givenlocation (Amherst, Northampton, East Windsor and Hackensack behavior? Valley) exhibit normalized For this investigation, CKoUC and CKoUDSS tests were performed on.NC and OC vertical samples at various MPPR (see upper part of Table 4.1) for vertical and inclined loading respectively. It should be noted, however, that the range in MPPR is relatively small. (2) Comparison of SHANSEP NSP from soils at different locations -- This testing program, shown in the bottom part of Table 4.1, included several types of tests ranging from CIUC 101 tests on NC samples with different inclinations to CK UDSS tests on both NC and OC samples, obtained from two to four locations. Ideally, comparison of NSP from SHANSEP samples at different locations should be made with samples which have the same values of avm,' v(L) and a . However, it was not always possible to have such conditions, since some of the tests were performed prior to start of this thesis. Therefore, the com- oarison is made with samples having approximately the same a vm (L) ratio, as shown in the lower part of Table 4.1. The vm normalized soil parameters (NSP) studied are qf/avc, Af, Yf, E/avc (or G/avc), $ and c/avm. f or For the sake of complete- ness, NSP data from the Connecticut Valley varved clays are compared to those from New Liskeard and Matagami in Canada. 4.2 EFFECT OF SAMPLE STRESS HISTORY (MPPR) Test data from CKoUC and CKoUDSS tests used to investigate the effect of sample stress history are summarized in Tables 4.2 through 4.4. Figures 4.1 and 4.2 show normalized stress-strain curves from CKoUC tests on OC (OCR=4) Amherst varved clay and from CKoUDSS tests on NC Northampton varved clay at various MPPR respectively. Test data in Tables 4.1 through 4.4 are samples which have a relatively small range in o from 2.0 to 4.0 kg/cm2 ) and MPPR ( vm 2.35). The following observations 102 (avm ranges ) ranges from 1.01 to are made with regard to the effect of MPPR on NSP (qf/Qvc' Af, Eu/Ovc, $ and c/avm) from four locations. (1) The MPPR has an insignificant effect on the normalized undrained shear parameters (qf/vc' Af, and NC 4 (assuming c = 0)) from CK oUC tests on NC samples from Amherst, Northampton, and East Windsor. This is also true with respect to qf/Cvc and Af of OC samples from Amherst. (2) The MPPR has an insignificant effect on (v)at T ( v) athmax rmCUS Thmax - vc from CKoUDSS tests on NC samples from and Amherst, vc Northampton, and Hackensack Valley. OC samples from Northampton also show the same trends. (3) In general, Eu/cvc at qf/Aqf = 1/2 from CKoUC tests is practically unaffected by MPPR, considering the accuracy with which soil modulus can be measured. The variation of Eu/ c is also less than the variation of G/vcvc from DSS tests. vc (4) Based on limited data from the same soil and from MPPR range for OC samples (OCR=4), the MPPR has a significant ef- fect on 3G/avc at 50% and 20% stress levels from CKoUDSS tests (Fig. 4.3). (5) For NC sample, Fig. 4.3 also shows the following: a. Based on Amherst data (two tests), the increase in MPPR decreases G/avc at 50% and 20% stress levels, while Northampton data (3 tests) show no consistent trend. But, collective data from East Windsor, Hackensack Valley, and Northampton 103 arved clay suggest a decrease in G/a with invc creasing MPPR: b. The fact that the NC Amherst sample has a lower a and a higher G/a than at other vm vc sites with the same MPPR suggests that the magnitude of in situ a per se affects shear modulus (i.e., G/vm vm decreases with increasingam) vm (6) Though limited data are available the results from Amherst and Hackensack Valley varved clay suggest that the MPPR has little effect on yf, though data from Northampton indicate an increase in f with increasing MPPR. Based on results from NC and OC (limited data) samples which have a small MPPR range and for two loading directions (vertical and inclined loading), the important findings are: 1. Varved clays from Amherst, Northampton, East Windsor and Hackensack Valley exhibit normalized behavior with respect to the undrained shear parameters S/avc Af, * (data only available for TC), and 2. v from DSS tests; avc The normalized undrained modulus for vertical loading is little affected by MPPR; but 3. The normalized undrained shear modulus of NC sample as measured from DSS tests most likely decreases with increasing values of both the in *Su qf for TC and Su = Thmax for DSS. 104 vm Based on the above, for any study of the effect of soil location on G/avc, the samplesshould have the same values of both and a vm . However, this requirement can not always vvm be fulfilled since some of the sites have quite different values of in situ maximum past pressure, avm 4.3 EFFECT OF SOIL LOCATION The results presented in Section 4.3 are from samples at four locations which have approximately the same MPPR, and avm CIUC tests on samples with different inclinations, and CUE, CKoUC, CKoUDSS and CKoUE tests on vertical samples are used for this study. 4.3.1 Results from CIU Tests A series of CIUC tests on samples with different varve inclinations was performed on NC Amherst and East Windsor samples. In addition, results from one vertical NC sample from Hackensack Valley are available. same magnitude of These samples had approximately the vm, ranging from 2.1 to 2.6 kg/cm MPPR ranged from 1.5 to 1.9 (Table 4.5). The Thus, comparison of the normalized undrained modulus data for all directions of loading can be made. The results from the CIUC tests are shown in Table 4.5 and Figs. 4.4 to 4.7. 1. These data show that the soil location: Does not have a significant effect on q/avc either at the maximum shear stress or at the 105 maximum obliquity condition obtained from =0, 45 and 900 tests. 2. Shows no apparent effect on Af and f (both at conditions) for all three the qf and ( 1 /a3 ) max loading directions, though the Hackensack Valley f at (a1 /a3 ) CIUC (8=0) test indicates a lower max [Such a difference may result from difficulty in picking the strain at (l/a3)ma x since the test had an almost horizontal (v/ah) versus curve (see Fig. 4.5)]. The test on East Windsor =13.5% before reaching (a1 /a3) was stopped at max conditions. 3. at qf (same as Has no effect on from CIUC (=90) = 45 and tests, though * from CIUC (08 0) tests. (a1 /a 3 )) at qf from CIUC = 0 tests are affected. effect of soil location on 4. at A significant at qf is only observed The reason is not clear. Shows no practical effect on normalized stressstrain curves from tests with 8= 0, 45 and 900 (Figs. 4.4 to 4.7). Variations in Eu/av vc at e=0.5% are not considered significant when considering the difficulty in measuring.Eu (Table 4.5). It should be noted that the variation in qf with loading direction from the CIUC tests is much smaller than that from UUC tests (see Chapter 2). The explanation of such a differ- ence will be presented in Chapter 6. 106 It was also observed that the mode of failure varied with sample inclination. vertical samples failed by bulging. The The inclined samples had failure planes within clay layers and the horizontal samples had failure planes across the varves. Two CIUE (=0) tests were performed on normally consoli- dated samples from Amherst and East Windsor.. These samples have approximately the same avm, avm (L), and thus vm ratio. avm The normalized stress-strain-obliquity curves from these two tests are shown in Figs. 4.4 and 4.5 to be essentially identical. In summary, the results from CIU tests on normally consolidated samples indicate that the Amherst and East Windsor varved clays have essentially identical undrained stress-strain strength parameters for vertical, inclined and horizontal loading. Sec- tion 4.3.2 will provide additional data from CKoU tests which show generally identical undrained stress-strain strength properties from Amherst, East Windsor, Northampton and Hackensack Valley. 4.3.2 Results from CK U Tests Test results from CU triaxial compression,extension, and direct simple shear tests on NC and some OC vertical samples from the four different locations, are presented in this section. 4.3.2(a) Data from CKoUC Tests Table 4.6 summarizes the test results from CKoUC tests at the maximum shear stress condition. 107 Data are shown for four locations at OCR=l and for two locations with OCR's equal to 2 and 4. These results were obtained from samples which have approximately the same vm ratio so that a comparison avm of the normalized undrained modulus could be made. A comparison of NSP can not be made at maximum obliquity condition for all tests, because some tests were stopped before reaching this condition. Test data in Table 4.6 and igs. 4.8 to 4.14 show that, for both NC and OC samples, the soil location has practically no effect on: 1. qf, Af,' f and E /vc at Aq/Aq = 0.5 u vc 2. Normalized stress-strain curves (Figs. 4.8 and (Table 4.6); 4.11, normalized stress paths (Fig. 4.9 for NC samples), the failure envelope at qf for normally consolidated samples (Fig. 4.10), and the normalized effective stress envelope (NESE), a plot of qf/avm versus 3. f/avm, in Fig. 4.13; and Unique plots of Af, f, and qf/3vc versus OCR (Figs. 4.12 and 4.14). The test data in Table 4.6 also show larger scatter in Af, * and E/aV f, than in qf/av. 4.3.2(b) Data from CK UDSS Tests Detailed NC and OC (OCR=4) DSS test data having about the same MPPR are compared to show the effect of soil location. Test results from samples having other OCR values are also used for comparison of Thmax/avc versus 108 OCR and · 1max/Qvm versus av/qvm Table 4.7 presents a summary of results from CK o UDSS tests on NC and OC (OCR=4) samples which have about the same MPPR. The comparison is made at the maximum horizontal shear stress (Thmax) condition. The soil parameters are T/avc, Yf, av/ovc The results in Table 4.7 and Fig. 4.3 and Figs. 4.14 to 4.16 shows: 1. For both NC and OC samples, the soil location has practically no effect on: (a) Thmax/avc and a vOvc (Table 4.7); (b) the "unique" plot of Tha /avc versus OCR (Fig. 4.14); (c) the normalized-stress strain curves (Th/Uvc versus y) (Fig. 4.15); and (d) the NESE, a plot of thmax/vom versus v/ vm (Fig. 4.16); 2. For both NC and OC samples, G/O vc at 50% stress level from CKoUDSS tests are mostly affected by the MPPR rather than the soil location (Fig. 4.3), though the data from Amherst show some deviation (probably because of a significant difference in the magnitudes of avm), 4.3.2(c) Data from CKoUE Tests CK0 UE test data are only available for Amherst and East Windsor. From the results shown in Figs. 4.13, 4.14, and 4.18, it is seen that the location had little effect on: (1) plots of qf/avc, Af, and at qf. f versus OCR; and (2) the NESE The difference in the normalized stress-strain curves 109 in Fig. 4.17 might be the result of differences of avm and MPPR rather than in soil location. in the values The higher modu- lus of the Amherst sample compared to that of the East Windsor sample is due to the lower a observed with G/o higher. vc vm at Amherst (same effect as data from DSS tests), though the MPPR is Based on NC CIUE test data (Figs. 4.4 and 4.5) from Amherst and East Windsor samples which had smaller differences in MPPR compared to the CKoUE tests, one would expect the same normalized stress-strain curves for these two clays if they had similar values of a vm The normalized effective stress envelope (NESE) at qf (Fig. 4.13) for vertical and horizontal loading are different. For horizontal loading, it is interesting to note that the results from NC CIUE and CKoUE test samples and OC CKoUE test samples plot on the same NESE. Further discussion of this point will be presented in Chapter 5. In summary, CKoUC, CKoUDSS, and CKoUE test data show that the samples from Amherst, Northampton, East Windsor, and Hackensack Valley (limited data) have very similar NSP (qf/vc ef, Eu/avc' , and c/ vc). from DSS tests and in E/avc Af, The differences in G/5vc values from CKoUE tests are thought to be due to the effect of variation in stress history rather than the soil location per se. 110 4.4 DISCUSSION The experimental evidence in Section 4.2 demonstrated for the range of MPPR under study that the varved clays from Amherst, East Windsor, Northampton, and Hackensack Valley exhibit normalized behavior with respect to undrained shear parameters (qf/ avc' Af, and C/3vm), and fairly consistent undrained modulus data for vertical loading, i.e., from CKoUC tests. However, shear modulus data from DSS tests show a trend of decreasing 3G/avc with increasing MPPR and/or in situ a Section 4.3 presented experimental evidence which indicated that: the varved clays from Northampton, Amherst, and East Windsor, in the Connecticut Valley, have the same NSP. Further- more, limited data from the Hackensack Valley varved clay suggest that this deposit has essentially the same normalized properties as those obtained from the Connecticut Valley. The above results suggest that varved clays which have similar bulk index properties and composition, though not necessarily having the same Varve thickness, should have the same NSP. Thus, if the nature of the varves in other deposits varies due to: 1. Large differences in relative positions of "silt" and "clay" layers; 2. Large differences in Atterberg limits of the silt and/or clay 3. layers; Variation in mineral composition of varves, especially the presence of cementing agents 111 such as carbonates; then, one might expect their NSP to differ significantly from those of the Connecticut Valley varved clay. An example of the possible effect of the difference in the nature of varves on NSP is provided by data from the Matagami varved clay located in Canada near James Bay (NGI, 1972). The two layers of this varve deposit are composed of a dark grey layer of soft fissured clay and a light gray layer of soft silty clay, generally with the thicknesses of 3/8 - 1/2 in. and less than 1/5 in. respectively. Compositional analyses show the presence of large amounts of carbonates in both layers. this soil is most likely naturally cemented. Thus, The soil profile shows that the thickness of the silt layer increases with depth. Table 4.8 shows the bulk Atterberg limits and undrained shear strength data from samples at two depths. These Su/avo values are higher than those for the Connecticut Valley (compared Su at the same OCR [see Fig. 4.14]). The increase is thought be be largely due to the difference in the nature of the varves, though the method of consolidation (SHANSEP method for Connecticut Valley varved clay versus RECOMPRESSION (vc = avo) method for Matagami varved clay) was also different (see Chapter 6 for general effect). Based on FV data (Fig. 4.19) where the method of consolidation is not a factor, S (FV)/avo for the Matagami varved clay is also significantly higher than that from the Connecticut Valley. As a result, the difference in laboratory strengths are probably due to inherent differences 112 in the nature of the varves, and especially the carbonate cementation. Basic differences in the nature of the varves are not always shown by variation in the bulk Atterberg limits. The best il- lustration of this fact can be seen from a comparison of the NSP of the varved clays from the Connecticut Valley and New Liskeard in Canada. A description of the general soil proper- ties and undrained shear strength (Su ) data of the latter soil are presented in Lacasse and Ladd (1973). Briefly, the varved clay from New Liskeard has about 1/2 in. thick clay layers and 3/8 in. thick silt layers. The natural water content of the silt portion varies between 24 and 30%, and varies between 60 and 80% for the clay portion. On Casagrande's plasticity chart, the CH "clay" layers plot above the A-line with WL = 70 + 10% and PI = 47 + 13%, and the CL and ML "silt" layers plot above and on the A-line with WL = 30 + 5% and PI = 10 + 6%. Thus, the silt and clay portions of New Liskeard varved clay have similar Atterberg limits to those from the Connecticut Valley (presented in Table 3.7), though composition analyses show large amounts of carbonates in both layers of New Liskeard varved clay (Quigley and Ogunbadejo, 1972). Furthermore, comparison of the bulk Atterberg limits of varved clays from Connecticut Valley and New Liskeard indicates that the former is only slightly more plastic. Figure 4.19 shows plots of S/Oo and SU/avc versus OCR from field vane and the CKoUDSS tests (RECOMPRESSION consolidation for New Liskeard varved clay versus 113 SHANSEP method of consolidation for Connecticut Valley varved clay). The significantly higher strengths for the New Liskeard varved clay compared to those for the Connecticut Valley are probably the result of the presence of natural cementing agents, e.g., calcite and carbonate. (Both the Connecticut Valley and New Liskeard varved clays have mainly illite and chlorite clay minerals.) These differences in the mineralogical composition, especially the presence of cementatin9 agents, seem to be a very important factor affecting the NSP of varved clays. of S(FV) The plots and Su(DSS)/ovo in Fig. 4.19 for Matagami and New Liskeard, both having the same cementing agent (carbonates), are essentially identical, despite having very different bulk Atterberg limits. Large variations in the relative portions of silt and clay layer may have a small influence on FV strengths. Limited data from the Lake Flushing varved clay in NY (Parsons, 1976) surprisingly suggest this. Despite a much smaller percentage of clay layers in the Lake Flushing varved clay compared with those from the Connecticut Valley and Hackensack Valley, SU(FV)/Ovc at an average OCR of four for the Lake Flushing varved clay is roughly equal to that for the Connecticut Valley (0.6 for Lake Flushing versus 0.74 for Connecticut Valley). The clay layers which have essentially the same Atterberg limits as those from Connecticut Valley represent about 10% of total thickness compared to about 50% for the other two deposits. 114 Important conclusions obtained from a comparison of the NSP of several varved clays are summarized, as follows: Varved clays which have the same bulk Atterberg limits, but coming from different geological deposits, do not always have the same NSP. Thus, bulk index properties do not necessarily indicate singificant differences in soil composition, especially the presence of cementing agents. Variations in the mineral compo- sition of varves seems to be the most important factor that affects NSP. Varve thickness and differences in the relative portions of "silt" and "clay" layer seem to have less influence at least on FV strengths. It should be clearly pointed out that the soil samples which came from the Connecticut Valley have the same bulk index properties and basic soil composition, and therefore should have the same NSP. 4.5 SUMMARY AND CONCLUSIONS Experimental evidence from this chapter has illustrated that, besides having the same index properties (see Chapter 3), varved clays from Connecticut Valley and Hackensack Valley have the same normalized behavior with respect to undrained shear strength parameters (qf/lvc' Af, $ and C/avm) . for all directions of loading: This is true vertical,inclined, and horizontal. Though the data show some differences in the normalized undrained shear modulus from the CKoUDSS tests, such differences 115 are due to the changes in the MPPR ( v ) and/or the in situ vm a rather than the soil location per se. vm Analysis of the normalized undrained modulus of a given varved clay shows that for samples which have the same OCR, the vm(L) sample's stress history (i.e., ratio) and magnitude of vm aVM had: 1. Little effect on E /avc and f obtained from the CK0 UC test; and 2. Some effect on G/avc obtained from the CKoUDSS tests, i.e., decreasing modulus with increasing MPPR and/or vm For the Connecticut Valley varved clay, the effect of sample stress history on the normalized undrained modulus and failure strains is expected to be more than the soil location. a In gene- (L) ral, the increase in the vm ratio will result in a decrease avm in the normalized undrained shear modulus and an increase in yf at hmax for SHANSEP samples which have the same and OCR. However, based on data for a small MPPR range, as used in the study, the MPPR ratio has practically qf/Uvc, Af, no effect on and C/avm (i.e., these clays exhibit the norma- lized behavior with respect to these parameters). Consequently, these normalized parameters from Amherst, Northampton, and East Windsor samples can be used to study the effect of stress system presented in Chapter 5. The suitability of using the SHANSEP method of consolidation for measuring the in situ normalized soil parameter is studied in Chapter 6. 116 The importance of soil composition was also illustrated. Variation in the mineral composition of varves, especially the presence of cementing agents, seems to be very important, this leading to increased strength compared to uncemented varved clay. Also, bulk index properties do not necessarily indicate changes in soil composition and thus soil properties. 117 EXPERIMENTAL PROGRAM FOR INVESTIGATING THE EFFECTS OF SOIL SAMPLE'S STRESS HISTORY AND SOIL LOCATION ON NSP Togic Investigation Type Test CK UC Sample . -1 -E N 0 N CIUE Soil Location: 1.12, 1.25, 1.50 1.07, 1.33 1 1.76, 2.35 1 1.01, 1.46, 1.52 2 1.25, 1.47 0,45,90 1 1.90 E 0,45,90 1 1.67 A 0 1 E 1.90 . 0 1 1.67 CK UC N o A E A E E H = Hackensack Valley CK UE A 0 A E ton 1.71 0 1 1.50 1.40 0 2 0 4 1.71 1.50 1.90 1.67 1.50 1.33 0 2 1.71 0 4 2.20 1.67 0 1 A CKoUDSS 0 1.76 N E H. KOUDSS 1.60 A E H Windsor N= Northamp- 1 1 A A= Amherst E= East 1.71, 1.81 1.90, .2-5 12H', T. . C I.UC vm (L) Om A KoUDSS Values of 0 A A Stress History of Soil Soil Location 1.52 1.67 __ E H 4 1.60 1.67 1.60 Table 4.1 118 (a CN rl i o L Om 00 III N H 0 * _oo 0 ko N < c H H 4-) C w _.-. . E U H 0 ~ H-i OU 4.4 C 8 o N D rNi0 .0 O -F 0 E U: r4 -1- N m 0 D -H > U) o 0,0r-4 oOo 0 i 0o 0o oo oo .DLAH _cc' ho 90I Q i~ 0% 0 0 0 HIH N H 0 N -0 __ L C CZ , toSo -tr-o, r 4C I I o) Ecn CA o 0) U] I) UU .0E I .. a)1 Er 4- ( -H 4 U -0 U 00 44 0 0 0 IV U)O 0 ,b1~3 rC-I A u () U u u D) a) 040 ) (n Table 4.2 -4 a)EiU1IiiI -La-- 119 c ,-i 4-4 tJ' > <: lix Nc o N < 0 CO LO (N L O o H o r 00 LA LA r H H '.0 v CO O I· O C o 0H,dP* W u o0 44 H - >4 I0 iI CO OV Oc 0· 0· 0) 4- OL, 0 94 Ix a l oW 0 H v 44 0 OO tz4 0 O O dP 0 w 0 0 Ez .I94 > HN I o . d40I 0 C4 04 . H N I Ln v 0 z Eqr W H P: O 00 CH- 0 _ 0 II 0 lb1 O C0 CC ( O a) Cd 04 _i 4,,4 _ __ 44 % L _>__ C 000 L000 0 00KD00 U) U) 111t00 v N 1N N 2TO 0000 0 (N 0 r-1 N 0 LA M 0 0 0 H-ll t:Ilb * * * * .* U] tsl9(1-r v _ ln r_ M1 ON -P4 r34 H CA Er P4 c .) 0 ' I b crn , X ,t cNVIS dpL do LO i4 -I w SN L II .W O-I .1 E-1 U) W 44 o r C/) w i)4V) (u 4I-) Cd ) >i0 ) E-1 %o I~n a) n 0 E. 0 . Cd 4ma) i pc, cc 1, ·- i H '4J .H On sc 4Jl M1 H (ltH 0 0 0 uI OI (1N o r(00 .IJ. '- .,J U z O a, Table 4.3 H I (N c I . I aZ aUtZm] aUZ 120 ' IV i 1 Ln ) I ) m 0 a agm Zo ZZ U N >4 > II 4 o o OVa~olr- ri1 N II oL UX N- U II 4) H rOzO L~~po o O U U O in 1I 0 11 r U (N H H N N H H d--P H HH 0: , iN O Cl H. E~ U) z I ~H U En U 0 U c L Er p4 z NI , H% O 0O LI H o H PI (n z 10 W r. rq G a) H G> if. 00 > S 0n n0 4. 00 0u _ ~. 3~ ID OICD \ oIO o\ 0 B~ "o ok I H to H 0 . -o k,.. -I ! m tQ C O44 u) >4 E 0 U) U 0 0 ; z N ru n> I I _ C0 .rG Erm1 r, U) D E4 r4 r 11, 12'1 t5 3: .4 Table 4.4 CN U II > I 0 0 - W 0 0 L N N N r o.- QO0 ,4 l . 1-6 ent m 0 .~ 0 L) r N) Ln L D 00 0, N N Lri N NN N 0 X oz 00 z OD N! H H E-4 H O_ I-I W O H L W zo C- OI I I Ide I ro O o,l e,o I H o N N H · o· o W en) . . Co 0 Lf00 LA I CY 0 O[ o . En p4 r- Ci I fO ULAH >N W u mn a n 001 C N o O o. 0n000 0 co N >1 rq U) 0 L dP _ ( d H UZ H 0 90 U) * L) LA O O' ' nI O ! ' _I rN O ri O rq O. r1 0' _-I U L r r- . 00 00 o 0o 0 o o U 0 · . . LA) .o. 0 U * . LA O r H H H C OO H H cn r o u, 0oo m O C) CJ) aO II Iu a) 11 In H H C0 ·rl 0 0 0 0S 0 Ot :: O 00 O r-4 N OCNHO-4HN *14 _ q .... 0 10 <4 _) OCDN0 H ___ __· a) 4J Wa w' 4J* U 0 OZ E- U H _< I H H .e I I I I H H I H I U C H I I N I N' I r H H H U U 122 I U H1 I en I U H w 0 Table 4.5 N lO i ; Iot 00 0c ~ O 00 00 O , ID~O n o O w w 00 CO o O N N IV H Ui N H _ -' o ooO oO _ _ _ .,C n 0 OoN E-1 o O D O o.o O. O 0 o U, cj 0' H H o. ,o C k '4 . 4' oo O _ .Q O . . Q O O H N CN n O P: 0 C5 . NO N. H H 0P Ot H . O v O ) '1 0:z 4dP O hor11 * W ) , ,1-4 *w1 r4t0 Orl I r, N LC) S r4S ,-r .0 H 0 4U O EE'.o . . . cLo 0I 4-) 0 . oc .0 e r-1 rd . k 0 E- U rZ 4 D, I 0 1DW0000 j 0o0a 0 C O 0 c C* n0 S N UZ I 0ccI0 M 0 O cr I I I E a) rU O cI ,1 .) )n 0444) UCO 4.) * *.r * >4 0 5 C *4 · r r N N v v 123 un i 0 D D3 Table 4.6 r- II . O _%r 0:0 N N W d O en Ez C,) b .a 4l U 0.. .- -IN > t Hn tQ H , . oo o-,-,oo -1 O t> C) 0 O W4 E4 C CS n 0 4-) | o 00 N- I ot Ia o ZCO r-4 o' 0 H 0 c0- -P a U-) ie o oO o o Mt -N to U W 0 I oo Q Qo . N O 0 ' L · - (D o ' t o . m(nU 4- C 14 4' >0 H 0. X _t av i S a, : I,.WIl '~ In IS, . ,,¢m n l ,-. cV M q I. H .0 COC sno U) z0 O N ,, 0 H HI -1 Table 4.7 N C ,.,.,CO C 124 UNDRAINED STRENGTH DATA ON SAMPLES FROM TWO DEPTHS OF MATAGAMI VARVED CLAY Data from Matagami Varved Clay from NGI Report No. 71307-3 WL = 94.1 + 3.0%; W = 40.9 + 3.2%; PI = 53.2 + 6.2% I * 2 Depth = 23 ft; WN = 98.7 + 3.5%; aO Type of Test K OCR CK UC(1 0.6 1.8 0.72+0.01 CK UDSS 0.6 1.8 0.39+0.01 0.6 1.8 0.48+0.05 CK UE 2 Su/a SU=qf S =f CKUE Kc OCR 0.60 1.7 .60 _ 0.60 Notes: (av of 4 tests) (avg. of 3 tests) U. Depth = 28 ft; WN = 87.8 + 0.8%; CK 0 UDSS 2 vm vm :1000 lb/ft (avg. of 2 tests) hmax WL = 76.1 + 0.7%; Wp = 36.9 + 0.9%; CKUC1) ; % Remarks · Type of Test = 550 lb/ft t ao =760 lb/ft2 ; S /avo v(3)=1300 lb/ft2 Remarks 0.57 1.7 0.34+ 1.7 PI = 39.2 + 1.6% Su .05 0.43 Su qf hmax (avg. of 3 tests) hmax S, (1) Failure across the varves was observed in CKoUC tests. (2) Failure by bulging of silt was observed in CKoUE tests. (3) Interpolated to these particular depths. Table 4.8 125 /F .6 1.4 1.2 /.o 0.a 0.6 0.4 0.2 0 o ! Z 3 9 s 6 7 9 9 10 /2 I! /3 AXIAL STRAIN, % ------ (°/aY)mox 3.O0 - - 2.25 s =2.2 / /~~~~~~~~~A °h 2to IA I. W |~, ,= 2.i K9/c,_ I 0 _..._ / I Z I 3 I * v,m L)190 ' ' I s 6 I 7 9 I 9 /0 I // I /2 /3 AYIAL STRAIN, % NORMALIZED STRESS-STRAIN CKoUC TESTS CURVES FROM ON OVERCONSOLIDATED AMHERST CLAY AT TWO vm(L) RATIOS "vm 126 VARVED FIGURE 4.1 rh; avc l U.a 0.6 bu #;- 0.4 0.2 C rl - !0 I NORMALIZED STRESS-STRAIN CURVES FROM CKoUDSS TESTS ON NORMALLY CONSOLIDATED NORTHAMPTON VARVED CLAY FIGURE 4.2 127 J~ - ! W~ r At h//hmlx -1 L OCA T/ON A C. 0 I0 E A A 0o 0 /o0 Fvc SO/IL i \'vm= /.7 3C SYM. n 4 90 H A U 0 OCR' 4 80 J4 *rrn ronges from 2. S t 70 60 s0 %I i I "'zo . I .0 .5 3.5 -. 0 2.5 vin4) v/n ?7 u~ = 0.2 At too 36 oic Th Ma 0- \ 0 E = East Windsor A mb7-h-er;t J L L\ /50 /-/ = Haockensac V/alley OCR-I\ N = Aorthampton n w, 0 I A ! I 3.0 2..5 t.O I 3.5 O'vm(z Oto n 3G EFFECT OF MPPR ON VALUES OF rv c FROM CKoUDSS TESTS ON NORTHAMPTON, AMHERST, EAST WINDSOR AND HACKENSACK VALLEY VARVED CLAYS 128 FIGURE 4.3 COMPARISON OF STRESS-STRAIN CIUC AND ClUE TESTS ON NORMALLY CURVES FROM CONSOLIDATED VERTICAL SAMPLES FROM AMHERST, EAST WINDSOR, AND HACKENSACK VALLEY 129 FIGURE 4.4 r, . l MPPR YM. L OCA TION 40C 40 -. o E. Windsv.r 1.0 1.67 57. / Amherst 9..0 1 90 65S5 Clue TESTS Jw - _;7 3.0 2.0 Stress in Ag/cm2 IU T I 0 I I 2 4 I I I I I 8 6 I /0 I I I /f J2 AXIAL STRAIN, Q % .ro i ii LOCAT/ON 0 4.0 4.0 A mherst HacKensocir 4.0 .vc E. Windsor A h ,P ; YM. MPPR I 0 1.67 56.0 1.90 .54 CIUC TESTS 58.4 .- J3.O C=- 6- -.. II2.0 ' Strres in ko/cm a 1A ,.F_ ..... __ r_ I I 2 . I I' 4 1_ I. 6 I AXI/AL STRAI#, 6. .3 CURVES I /0 8 I I /. % FROM CIUC AND CIUE TESTS ON NOR- MALLY CONSOLIDATED VERTICAL SAMPLES FROM AMHERST, EAST WINDSOR, AND HACKENSACK VALLEY 130 FIGURE 4.5 0.8 . ; lU . SYM. wN LOCATION Ovm E. Windsor 58.7 1.67 0.6 O An herst A 60.3 1.90 I -- 0.4 LI ! 0.2 II I 2 t I I Mi I I ! I' I 4 I,. I iI I I I a 6 I. . 12 10 14 AXIAL STRAIN, % 4.0 . l LOCA TION YA. /0 358.7 E. Windsor 0 30 A mherrt -- 1 60.3 --- 67 190 _~~ _ &3 ,I I.U _ I 0 I I 2 I I 4 I I 6 I I 8 I I o0 I I 12 I '4- AXIAL STRAIN,% COMPARISON OF STRESS-STRAIN CURVES FROM CIUC TESTS ON INCLINED SAMPLES (45 ° ) OF NORMALLY CONSOLIDATED AMHERST AND E. WINDSOR VARVED CLAYS 131 FIGURE 4.6 LU w 1 I LOCAT/ON SYM. 0.8 E. Windsor _ 0 Amnherst Wn / Cr. ¢ 4.0 167 S3.7 1.90 61. 4.0 rm 0.6 -, _ 5 O~~~r 0 tr. 0.a \/ I 'I 1 0 I I 2 c I Ii I I II I I I 6 4 0 I t I /4- /2 AXIAL STRAIN, % 4.0 3.0 SYM. LOCATION * E. Windror 4.0 0 Amherst 4.0 vcm 8,C,, .67 1. 7 1.90 6.2 3 2.0 r. I 0 r I I 2 I q. I II 6 I I U . i I /0 I IZ I AX/AL STRAIN, % COMPARISON OF STRESS-STRAIN CURVES FROM CIUC TESTS ON HORIZONTAL SAMPLES OF NORMALLY CONSOLIDATED AMHERST AND E.WINDSOR 132 VARVED CLAYS FIGURE 4.7 1/ 0.6 - 0.5 _- I 1[ 0 F (r 0 0 *0 C3 V * 0 Ia I ed5 A A 0 0.4 A I r lrvc 0.3 0.5 . u . I SYM. 0.2 _ 0.1 A L "'00 ¢ |MPPR 'vm A 4.0 J3 v 3.4- 3.3 O 3.6 2.4 3.o 2.4- 2 O * * LOCATION 12/ Northompton .03 vorthompton E. Windxor /.50 E. Windsor 2. 6Y 2.4 1.12 E. Windsor 2.99 1.6 1.87 Amherst II 0. I I II 1.0 I [ I I I I! I. I.S 2. 4 I. 6 I. 8 I !. 0 /2 AXIAL STRAIN, % NORMALIZED STRESS-STRAIN CURVES FROM CKoUC TESTS ON NORMALLY CONSOLI DATEI[) VERTICAL SAMPLES FROM CONNECTICUT VALLEY 133 FIGURE 4.8 /14 c% 1-. -J J - cn C-D Igm I / cn I- I w zZ Y L z0 0 O L. O C-) n w C) I0 a.J $i~ b, 11t to --Z a-. '6 0 0\o os \os S\oOs V,~o %O lbo cn U) w o ei i v a<c X lb'b I- cs t- o a w ) It aZ n C Cs hj ~p:jic LL W 0I t + t C4 ^ 2 0 4 LL _ ~Y4 N4 . W N z 0 e0 cr <I4 I ' I' ,<lia I i z0 LI <H tII 4q ,, u of 0 0 'T 2t W 0 I !~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 1 q4 0 I I Nb 134 FIGURE 4.9 Z wX LL I- WJ e4 .. v-. lcu U0 ) L aJ 0 z z0 ,%&C %4. 11 cr a wCrr 135 FIGURE 4.10 a: -cr, lrvc AXIAL STRAIN, /@ 4.0 h %Fr 2.0 AXIAL COMPARISON STRAIN, % OF NORMALIZED STRESS-STRAIN CURVES FROM CKoUC TESTS ON OVERCONSOLIDATED AMHERST AND EAST WINDSOR VARVED CLAYS 136 FIGURE 4.11 14t'~SYM. SOIL L / 0 C, 0 A · I E X\ .,[/..) TIONIV 1.7/-1.9 15'-167 H .8s- ,,m v lI. N .33 Af 0.6 0.4 I o I 3 2 (a) I 4 I 12 I Amherst E = East E-- /0 8 Cf6 P 6 OCR _ Windsor H = H4acXensocK Valley N = Northornpton 6 1' C K0 1/ 4 2 uA (b) d / "'" I I I 2 3 4 s 6 OCR Af AND Ef VS OCR FROM CKoUC TESTS ON AMHERST AND EAST WINDSOR VARVED CLAYS 137 FIGURE 4.12 _ | .~_ -I 0 == E I N I- t 99 ; -. : ONO E 0 . c cn Ibl b' ON: . 00 II i*, 0th 6 w 00 a: Ge ct %, %I -* Y zaI ou E oth t4%i os pi K -, 11 -4 -4.1 "C1q 'p IT N . 0I<^ tiQ 0 x r 0 Q! 2: Joz140t -~ LyK I w t {Q O .Q _Z -- () a o C 'C< Ow 11 c Ow fi 3 n '4- WL9 _ o" 0' LL W Ill Ill w Ici 0 t llOC I . N Iv N 1 / w / Q l 'IN / 0W I O N / / 1I)J <5 <2/ / / I Cr5 / ,= ,· , Ii C1 I Ie 16 Z I O (CJ ts~ r: O I )l'' 138 FIGURE 4.13 SE' &VC OCR NORMALIZED UNDRAINED SHEAR STRENGTH OF CONNECTICUT VALLEY AND HACKENSACK VALLEY VARVED CLAYS FIGURE 4.14 139 0.2 0 d, % AU qvc ar' yo -1 'ch &IV 0 4 8 /2 /16 Jo 24 (', % NORMALIZED STRESS-STRAIN CURVES FROM CKoUDSS TESTS ON NORMALLY CONSOLIDATED NORTHAMPTON, AMHERST, EAST WINDSOR, AND HACKENSACK VALLEY VARVED CLAYS FIGURE 4.15 140 - '.4 6>7 I' .iI cn Q I- I -JU) -J 10 Io 1%i N f6 t;· v Or zW LL Zcn 0> .- I t., *b o rZt Q P R (zi 4 (4 waJ Z E NO k . sJ t1 A1 .O I * oo' < ----- I B <I .I - ti 141 FIGURE 4.16 A &.C . 2 0 4 /0 8 6 14 AXIAL STRAIN, % 4.0 , '1 I I I I I I .... I I V I I ': LOCATION 20 .i "'0 Jsn I I I I 4 I I 6 i ,•l) wN m,, . % * Eat Windsor/.67 58.7 0 Amherst 2.d.O I 63.1 I 8 /0 /2 /1 AXIAL STRAIN, % NORMALIZED STRESS-OBLIQUITY-STRAIN FROM CKoUE TESTS ON OVERCONSOLIDATED AMHERST AND EAST WINDSOR VARVED CLAYS 142 FIGURE 4.17 1 /.4 . SYM. .2 1.0 4 0 \ SOIL all LOCAT/ON E. Windsor /.671 Amherst Z.9-2.2 0.8 0.6 0.4 0 m (L) = 2. o.:I L _ I I I. 2 3 I. 4 I. aPt JS I. I 6 7 _ OCR Is /9 13 /2 12 I 'C /c OCR VS OCR FROM CKoUE OF EAST WINDSOR AND AMHERST VARVED CLAYS Af AND Ef TESTS 14 3 FIGURE 4.18 : - l r~~~~~~~~~~~ SYhlM. So/L TYPE OF TES T 1OCA TION New Lisleard /.o x New LisKeoard 0 rl Moa 9 0mi I/DS CKo rv C K I DSS Malagami FY i o0. - / FV of the FV from Motogami x/ and ew Liseord Su °vo ._ Connecticut Volley I/ xd/ Yaorved Cloy Loodd Foott (/977) / 0.6 / - T/ / /J 0.4 XO ee T° ½VC X Pvc AK1;0 'rop C VDS tests of the Connecticvt l hey V/ored C/oys a2 I I I. _ ... / I 3 -I + . - I--- 6 I I 7 8 9 OCR COMPARISON OF THE NORMALIZED UNDRAINED SHEAR STRENGTHS OF CONINECTICUT VALLEY, MATAGAMI, AND NEW LISKEARD VARVED CLAYS 144 FIGURE 4.19 5. EFFECT OF STRESS SYSTEM ON UNDRAINED BEHAVIOR FROM SHANSEP SAMPLES 5.1 INTRODUCTION The general requirements for accurately measuring the undrained stress-strain-strength behavior of varved clay and its anisotropy are: 1. Performing tests on samples having the same soil structure and physical conditions as the in situ varved clay; 2. Performing tests on samples in a manner to insure that the stress system, time, and environment (temperature, pore fluid characteristics, etc.) are.the same as those which will be imposed in the field. From these requirements, the major factors that could affect the measured behavior are; (1) sample disturbance; (2) the stress system before and during shear; (3) time prior to and during shear; and (4) the environment. The effects of stress system on undrained behavior are studied in this chapter. All data are obtained by the SHANSEP method of consolidation and time and environment are treated as constants. The effects of sample disturbance and alternate methods of consolidation will be covered in Chapter 6. The stress system, both prior to shear and that applied during shear means the direction and relative magnitudes of the 145 three principal stresses. The stress system prior to shear is therefore that resulting from the relative magnitude and the direction of lc' a2c' and a3c' Laboratory samples are frequently isotropically consolidated whereas the in situ stress condition is generally anisotropic, with a K o stress state often being of greatest interest. The applied stress system during shear is that resulting from the applied total stress path, which in turn specifies the relative magnitude and Aa 3 during shear. and direction ofAol1 A Thus, the direction of alf versus 2 alc (i.e,, rotation of principal stresses) and the magnitude of the intermediate principal stress are the variables for the applied stress system during shear. The' study in this chapter concentrates on three major topiics, as follows: 1, Effect of Ko versus isotropic consolidation, i.e., the study of the effect of stress system prior to shear; 2. Effect of the intermediate principal stress (a2 ); 3. Effect of different stress system used for causing shear parallel to the varves. The section presents data from tests having different directions of alf relative to the orientation of the:s-%rves and from tests with rotation of the principal stresses. Such effects.are in- vestigated by comparing the resultant NSP (qovc' Af, E/avc, 4 and c/vm). Table 5.1 presents a summary of the experimental program. It consisted of: 146 1. CIU and CKoU tests on vertical and horizontal samples of OCR's of 1, 2, and 4 for investigating the effect of K o versus isotropic consolidation; 2. CIUC and CIUE tests on vertical and horizontal samples at OCR's of 1, 2, and 4 for investigating the effect of 3. a2 in CIU tests; CKoUC, CKoUE, CKoUPSC, CKoUPSE, CKoUDSS(C), CKoUDSS(E) tests on normally consolidated samples for investigating 4. and the effect of a 2 in CK 0 U tests; CIUC tests on inclined samples at OCR's of 1, 4, and 20, CKoUDSS and CDDS tests on vertical samples with various OCR's for investigating the effect of testing method for shearing parallel to the varves. As noted previously, the SHANSEP method of consolidation was used in the study. Experimental results from K consolidated SHANSEP samples in Chapter 4 indicated that Connecticut Valley varved clays exhibit normalized behavior over the stress range of interest (except perhaps for modulus) and samples from different locations also had the same NSP. Therefore, the NSP con- cept and test results from three varved clays (Amherst, Northampton, and East Windsor) are used for this study. Appendix C presents details regarding the test results and testing conditions. The general testing procedures for triax- ial, direct simple shear, and plane strain tests were presented in Section 3.5. The special method of consolidation used for 147 CKoUDSS(C) and CKoUDSS(E) tests is discussed in Section 5.3.4. It is emphasized that, as a result of using the SHANSEP method of consolidation, these samples do not necessarily have the same soil structure as the in situ soil, as will be discussed in Chapter 6. In addition, the structure of isotropically con- solidated laboratory specimens will obviously be different from that of th( in situ soil. Becau.;e the soil structure of SHANSEP samples is different from that )f the in situ soil, the effect of stress systems, as shown from the studies presented in this chapter, may not truely reflect the> in situ soil behavior. However, the SHANSEP method of consoli¢lation was chosen because disturbance due to separations of tiie varve , especially with horizontal and inclined samples, c()uld seriously affect the results, if the RECOMPRESSION method of :onsolidation had been used (see Chapter 6). In ad- dition, th ~ effect of material anisotropy component (defined in Chapter 2) could be mostly separated from that due to the struc- tural and Lnduced anisotropy (see Chapter 7), therefore helping to provide a basic understanding of anisotropic behavior of the varved clay. Finally, the results are applicable for a given soil structure even if this material does not necessarily have the sttme NSP as the in situ soil. 5.2 5.2.1 EFFEC! OF K VERSUS ISOTROPIC CONSOLIDATION Met] od of Investigation Tab,Le 5.1 lists the experimental program that is used 148 for this study. For vertical loading, the effect of Ko consoli- dation is shown by comparing NSP from CKoUC and CIUC tests, while CK0 UE versus CIUE tests show the effect for horizontal loading. The laboratory maximum past pressure o (L) was either avm Volume Change Data from CIU and CK U Tests 5.2.2 AV Figure 5.1 shows plots of volumetric strain, Vo , versus the vertical consolidation stress, avc' for samples from East Windsor. Data from CIUC and CIUE tests are compared with those from CK UC and CKOUE tests. 0 Figure 5.2 presents Ko versus OCR data from a Ko cell and Ladd's (1975) recommended relationship. Measured Ko values from CKoUC and E tests agreed quite well with the recommended relationship. For simplicity, since Ko is nearly equal to unity at an OCR of 4, CKoU tests with an OCR of 4 started shear with Kc= 1.0 It is seen in Fig. 5.1 that isotropically consolidated East Windsor samples compress only slightly more than K o consolidated samples. Based upon these rather limited data, one can conclude that the stress system during consolidation (i.e., K o versus isotropical consolidation) has little effect on the volume change during consolidation, at least in NC range. Since there was little variation in the natural moisture content (WN) of the East Windsor samples, both = 1 and Ko consolidated specimens have approximately the same water content prior to shear. Thus, water content per se is not a factor in comparing CIU versus 149 CKoU test data. However, the same final water content does not necessarily mean that CIU and CKoU test samples have the same soil structure. One would expect Ko consolidation to retain and/or produce a more parallel orientation of particles perpendicular to the vertical direction. Hence, it is likely that the soil structure of these samples will be different. Moreover, this difference should still exist for overconsolidated samples of an OCR of 4 even though 1Kis equal to 1.0 (Martin and Ladd, 1975). 5.2.3 Re'sultsfrom CI-UCand CK UC Tests Test results from CKoUC and CIUC tests are summarized in Table 5.2 and Figs. 5.3 through 5.10. Before discussing the re- sults, some discussion of "normalized effective stress envelope (NESE)," a plot in terms of p /" f 1. vm versus qf/m is in order. In order to compare NC* and OC samples and to account for variation in avm, all results are divided by avm 2. Results of triaxial tests are plotted for convenience in terms of q and p (or q/3vm vs. p4m yield an intercept a (or avm 3. ) ) which and a slope a. In order to convert the above parameters to normalized Mohr-Coulomb (M-C) strength parameters, i.e., to plots of Tff/avm versus aff/avm to give /avm and ~, the following relationships were used. *Note that p and q divided by a of all NC samples will end up at the same point in the plotvgf NESE if the soil exhibits normalized behavior. 150 sin 4 = tan C/avm = a/cos Tff/Vm= avm af qf/avm cos = / Pfvmqf/vm f/vm sin These assume that the failure plane is given by the point of tangency between the normalized (with respect to avm ) Mohr circle at failure and the normalized M-C envelope, whereas, in fact, the inclination of the actual failure plnae is not known. 4. Reference to Fig. 5.8 shows that there are several normalized envelopes when NC and OC samplesa are considered collectively. represents the NESE at ( also at qf when Pf/vm Note, however, that Line A 1 /a3 ) for all samples and max is less than about 0.3. These envelopes were used to obtain the corresponding values of and c/vm vm except in the case of NC samples when 4 was computed from a assuming a=c=O. 5. To avoid confusion, a NESE with a bar on top (i.e., NESE) refers to Mohr-Coulomb normalized effective stress envelope (i.e., a plot of aff/avm versus Tff/avm), whereas the term NESE designates an envelope in terms of Pf/vm versus qf/3vm Data in Figs. 5.3 through 5.10 and the results in Table 5.2 show that K o consolidation (relative to isotropic consolidation): 1. Did not significantly change qf/avc at OCR's of 1,2, and 4. 151 2. Did not significantly change at Tff/a c at (al/a3)max an OCR of four, but decreased it at OCR's of 1 and 2 (Table 5.2). 3. Had little effect on Af at qf, but increased A at (a1 / 3) 4. at low OCR (Table 5.2). max Significantly decreased f at qf (Fig. 5.6(a)). 5. Did not change f at ( 1 /a3 ) of samples at OCR's max of one and two, but decreased f of the sample with an OCR of four. 6. At low OCR, caused a significant lowering of the NESE at qf (Fig, 5.8). At an OCR of one, (c=O) of NC sample decreases from 270 + 1.5° to only 21 °. + 0.70 This reduction in NESE becomes less pronounced as the OCR approaches four. 7. Did not change the NESE at (a1 /a 3) except per- max haps only slightly changing (=0) for NC samples because of the difference in pf. 8, Increased the secant Eu/qf at the same applied shear stress level (Aq/A qf) for OC samples (OCR=2 and 4), based on limited data, whereas K consolidated apparently did not significantly affect E /qf for NC samples (Fig. 5.9). 9. Increased Eu/ vc at a = 0.2% for OC samples and decreased EU/avc at the same strain with NC samples (Fig. 5.10). The compensating effects of the stress system during 152 consolidation on the NESE at qf and the pore pressure response caused qf(V) to be nearly identical. CK 0 UC samples have a lower NESE at qf (Fig. 5.8), but higher values of pf than CIUC samples (Figs. 5.7 and 5.8). The decrease in NESE at qf with Ko consol- idation is consistent with data on other clays (Ladd, 1965). The lowering of the NESE at qf from CKoUC tests might be explained by a difference in the degree of mobilization of friction and cohesion in the clay and silt portions. According to the concepts of Schmertmann and Osterberg (1960), the mobiliza tion of cohesion and friction and a potential failure plane are strain dependent. The friction component only becomes fully mobilized at large strain, whereas the cohesion reaches its peak at low strains. Since CIUC test samples have a higher f at qf than CK0 UC test samples, the amount of friction mobilized at qf is more in isotropically consolidated samples than in K o consolidated samples at low OCR and hence K o values. At (a 1/ 3) , the NESE is hypothesized to represent the fully mobilized frictional strength of both clay and silt layers. The fact that,.despite having different failure mechanisms (CIUC test samples failed by bulging while CKoUC test samples failed by developing distinct failure planes across the varves at the end of the test), NESE at (/a3)max of CIUC and CK UC test samples are identical (Fig. 5.8) suggests that in the undrained tests the frictional strengths of both clay and silt layers in the CIUC and CKoUC samples are fully mobilized. should be noted in Fig. 5.8 that the same NESE at ( It 1 /a3 ) max 153 also holds for both NC and OC samples from CIUC and CKoUC tests. Consequently, NESE at (l1/a3)max for vertical loading is independent of the stress history and stress system during consolidation. At low OCR, the decrease in Tff/avc at (a1 /a3 ) with max CKoUC tests is due to the fact that CKoUC samples exhibit more strain softening. This can probably be explained by the fact that distinct failure planes formed in the K o consolidated samples The "soil structure" effect on NSP might be inferred by comparing NSP of samples from CIUC and CKoUC tests at an OCR of four, since-in both tests shear started at the same stresses. Table 5.2 shows that qf(V) and Af values of these samples are practically identical. These results, therefore, indicate little effect of soil structure on qf(V) and Af. However, soil struc- ture apparently does have an effect on the undrained modulus, as indicated in Fig. 5.9. In conclusion, the stress system during consolidation does not significantly affect qf(V) and NESE at (a1 /a3 ) for vermax tical loading, but it has an effect on the envelope at qf and the stress strain and pore pressure characteristics. 5.2.4 Results from CIUE and CK UE Tests Test results from the CKoUE and CIUE tests are summarized in Table 5.3 and Figs. 5.5, 5.6(b), 5.7(b) and Figs. 5.10 to 5.13. These data show that K o consolidation relative to iso- tropic consolidation: 154 1. Decreased qf/ vc by about 15% practically independent of OCR (Table 5.3). 2. Decreased Af at qf and ( 1/3) of normally consolidated samples, but did not significantly change Af of overconsolidated samples (OCR=2 and 4), shown in Fig. 5.5.b. Unlike the samples from triaxial compression tests, samples from CIUE and condition max Thus, for CUE and CKoUE CK UE tests reached qf and (a/a 3 ) at the same strain. test samples, Af and NESE at qf are identical to those at ( 1 /a3 ) . However, ~ (c=0) of NC sample max is increased due to lower Pf/3vc (Table 5.2). 3. Did not change ef at qf or (a1/3) . The f max is also practically independent of OCR (Fig. 5,6(b)), 4. Decreased Eu/-vc at the same strain of both NC and OC samples (Fig. 5.10). 5. Had little effect on Eu/qf at OCR of one, but OC CKoUE samples have lower E/qf samples. values than CIUE This reduction increases with increas- ing OCR (Fig. 5.13). The fact that samples from both CIUE and CKoUE tests had distinct failure planes across the varves (though less visible in NC CKoUE test sample) probably partly explains why the NESE at ( 1 /; 3) or at qf from CIUE and CKoUE tests are identical. The lower pf in the NC CKoUE test sample relative to that in 155 the CIUE test sample explains why (c=0) of the NC W E test sample is larger, since NESE are identical. Since NESE is not affected by the stress system during consolidation, the decrease in qf(H)/vc and Eu/3vc of CKoUE test samples relative to those from CIUE test samples is caused by the development of larger excess pore pressures in CKoUE test samples. These are two possible reasons to explain this different excess pore pressure at failure (Auf). 1. The difference in the magnitudes of Aqf due to the rotation of principal planes: The principal planes are rotated by 90 degrees in CKoUE test samples which have K o less than one. In these samples, shearing first causes q to decrease to zero and then to increase in the horizontal direction. OCR=1.0, when q = 0, the K At consolidated sample has a much lower p than the isotropically consolidated sample (Fig. 57). Thus, for this NC CKoJE sample, in spite of having a lower Af, pf is smaller. 2. A difference in soil structure: The CKoUE test samples may have a more preferred particle orientation compared to that of the CfIUEtest samples, in spite of insignificant differences in the final water contents. It is difficult to assess the magnitude of the effect of soil structure on the difference in *qf. However, the fact that the K o consolidated sample developed larger pore pressure during 156 shear at OCR = 4 (Ko=1l),suggests that there is a soil structure That is, a more preferred particle orientation leads effect. to an increase in the pore pressure developed in CKoUE samples, i.e., when alf acts in the horizontal direction. This hypothe- sis is supported by the results of Duncan and Seed (1966(a)) on Kaolin. In summary, the decrease in qf/vc and EU/Uvc of NC CKoUE samples are thought to be due to both the effects of the differ ence in Aqf and in the soil structure, while the decrease in and E qf/vc v of OC samples are mainly due to the differences in the soil structure. Test data in this section, therefore, show that the stress system during consolidation has a considerable effect on qf/v Af, and E/avc from horizontal loading. (or at qf) nor perhaps effect on NESE at ( 5.2.5 Summary and Discussion A. 1 /a3 ) However, it has no f. Summary of Principal Findings from the Study of K. Versus Isotropic Consolidation (a) Behavior from Vertical Loading (Triaxial Compression) Test data from CIUC and CKoUC tests show that: 1. The stress system during consolidation has an insignificant effect on qf at all OCR values studied, due to the compensating effect of Ko on developed pore pressure and NESE at qf. The CKoUC test samples (1 < OCR< 4) have a lower NESE at qf, but have larger pf values than the CIUC test samples. 157 At an OCR of four, CKoUC and CIUC test samples have essentially the same qf and Af (also Ko=l). 2. The CKoUC test samples, especially those at OCR of one and two, exhibit considerable more strain softening behavior than CIUC test samples. That is probably due to the formation of failure planes during shear in the CKoUC test samples. 3. Because f at qf of CoUC test samples, especially that of the NC sample, is smaller than ef of CIUC test samples, NESE at qf from CKoUC tests is lower. 4. For both CIUC and CK UC test samples, the difference between NESE at qf and (/a3)max decreases with increasing OCR, as the difference in axial strains at qf and ( 1 /a3) of both tests also max decreases with increasing OCR. 5. Despite having different failure mechanisms (CIUC test samples having failed by bulging while (CKoUC test samples developed distinct failure planes across the varves), NESE at (a /a 3 ) from CK0 UC max and CIUC tests are identical. 6. Eu/qf from OC CIUC test samples are lower than those from OC CKoUC test samples, though Eu/qf of NC CIUC and CKoUC test samples are practically identical. (b) Behavior from Horizontal Loading (Triaxial Extension) Test data from CKoUE and CIUE tests lead to the follow- ing findings: 1. CKoUE test samples have about 15% lower qf than 158 CIUE test samples at OCR = 1 to 4. 2. The decrease in qf is due to the lower pf (increased pore pressure), while the NESE is unchanged. For normally consolidated CKoU test samples, the increase in Auf is thought to be due to both the increase in Aqf and to differences in the soil structure. For overconsolidated samples, such a decrease is mainly due to the difference in the soil structure. 3. For both CIUE and CKoUE tests, the qf and (1/03) conditions occur at the same strain and they have the same failure mechanism. (Both tests develop a failure plane across the varves.) Thus, their NESE at (al/a3)max which are also the same as those at qf are identical. B. Uniqueness of NESE at (Ol/a3)max It is seen in Figs. 5.7 and 5.8 that the same NESE at (/3)max holds for both NC and OC samples from CIUC, CKoUC, CIUE and CK UE tests. Furthermore, upon comparing the stress systems of CIUC, CKoUC, CIUE and CKoUE tests, one can conclude that NESE at ( 3)max for failure across the varves (since both TC and TE test samples have potential failure planes across the varves) is independent of: 1. The stress system during consolidation; 2. The magnitude of 2 and the rotation of principal planes (hence, the stress system during shear); 3. The magnitude of v (m of CIU tests is 4.0 kg/cm 2 159vm 159 while av vm is 3.6 kg/cm2 for some of the CKoU tests; 0 additional data from RECOMPRESSION samples (presented in Chapter 6) which have aVm ranging from 1,6 to 2.4 also indicate this independency). The fact that despite bulging type of failure observed at the end of the test, the NESE at (al/a3max from CIUC tests are identical to that from CKoUC, CUE and CKoUE tests, in which their samples developed distinct failure plane across the varves at the end of the test, suggests that CTUC test samples also failed across the varves. Additional data confirming the independency of the NESE at (al/ 3 )max from the magnitude of 2 from CIUC (G=90) and CIUE (8=90) tests on NC and OC samples and from a CKoUPSC test and from two CKoUPSE tests on NC soil will be presented in Section 5.3. The uniqueness of NESE at (l/a3)max suggests that it can be considered as a material property. On the other hand, NESE at qf, when it is not equal to that at (al/a3)max (e.g., NESE at qf for CIUC and CKoUC tests when > 0.3) can be greatly affected by the stress system during Pf/vm consolidation and the direction of loading. 5.3 EFFECT OF INTERMEDIATE PRINCIPAL STRESS 5.3.1 Method of Investigation The investigation of the effect of 2 on NSP was conducted on both K o and isotropically consolidated SHANSEP samples (Table 5.1). 160 The effect of a 2 with CIU tests is shown by comparing NSP from CIUC and CIUE tests. CIUC tests on vertical samples (=0) and CIUE tests on horizontal samples (=90) study the effect for vertical loading. veritical samples (=0) samples (=90) are performed to NSP from CIUE tests on and those from CIUC tests on horizontal are compared for the case of horizontal loading. Figure 5.14 presents the state of stress during shear of these samples. It is seen in Fig, 5.14 that, when using horizontal triaxial samples, one of the a2 directions is perpendicular to the varves instead of being parallel as should occur in situ. For CKoU tests, the effect of a 2 is shown by comparing NSP from triaxial and plane strain condition. NSP from a CKoUPSC test on a normally consolidated sample from Northampton (Lacasse et al., 1972) and that from a CKoUC test on a normally consolidated sample from Amherst are compared for the case of vertical loading. For horizontal loading, NSP from two CKoUPSE tests (Lacasse et al., 1972) and those from a CKoUE test are compared, all being normally consolidated. Since the DSS device is thought to have a state of stress during shear closer to.that of plane strain (Ladd and Edger, 1972),it was also used for tests on two normally consolidated inclined (=45) samples. These CKoUDSS(C) and CKoUDSS(E) tests simulate CK0 UPSC and CKoUPSE tests, respectively. Section 5.3.4 will present the testing procedures and results as well as the problems of interpreting test data from these special DSS tests, 5.3.2 Results from CIU Tests Test results from U-UC and C-IUEtests on vertical and hori161 zontal samples are summarized in Tables 5.4 and 5.5 and Figs. These test results are from samples which have 5.15 to 5.19. approximately the same moisture content. Thus, the differences in NSP from CIUC and CIUE test samples are mostly the result of the difference in the magnitudes of 02 and perhaps also in the direction of 2 relative to the varve structure. Test data show that for vertical loading, shear in extension is relative to shear in compression: 1. Slightly increased (though considered insignificant for practical purposes) (~1/~3) max 2. qf(V)/avc and Tff/vc at for both NC and OC samples; Caused an increase in pore pressure parameter A for OC samples, but had no effect on A for NC soil (Fig. 5.19); 3. Increased NESE at qf, though NESE at (a1/3)max is not affected (Fig. 5.17); 4. Increased Eu/avc at e =0.5%, though the maximum increase was less than 30% (Table 5.4); 5. Increased (c = 0) of NC samples (Table 5.4). For horizontal loading, shear in extension relative to shear in compression: 1. Decreased qf(H)/vc and Tff/avc at (/f3)max by 5 to 15%, this effect also decreasing with increasing OCR (Table 5.5); 2. Increased the pore pressure and hence A (Fig. 5.19); 3. Increased (assuming c = 0) of NC soil 162 (Table 5.5) because of lower Pf/Vm; 4. Did not change NESE at qf or (al/a3)max (same envelope), Figs. 5.17 and 5.19; 5. Slightly decreased E /0vC at = 0.5% but the maxi- mum decrease is only 30% or less (Table 5.5). An analysis of the effect of a2 on E/avc can not be made without assuming that varved clay is an isotropic material. The vertical strains were measured in 0=0 samples, whereas the "horizontal" strains (with respect to the in situ orientation) were measured in 0=90 samples. shown by comparing Eu/vc Since the effect of a 2 on E/Ov is from CIUC (.=0) and CIUE (8-=90)tests for vertical loading, and those from CIUC (=90) and CIUE (0=0) tests for horizontal loading, it is necessary to assume that the material behaves as if it were isotropic. With this assumption, a2 has relatively little effect on Eu/avc for both vertical and horizontal loading within 30%. (Tables 54 and 5.5), the variation being Though a difference of 30% is not considered signi- ficant (considering the limitation in the method of analysis), it can not be concluded that a2 has no effect on E/ vc because of the unknown direction of the error due to the assumption of isotropy. The fact that the modulus from than for 0 =90 samples is always larger samples, independent of the type of test (i.e., when comparing TC (=90) versus TE (8=0) tests or TC (=0) sus TE (=90) ver- tests) suggests that the use of samples with dif- ferent inclinations affects the outcome of the results at least as much as the value of the intermediate principal stress. 163 For an isotropic "ideal" material, interpretation of test data in terms of Toct and aoct' rather than p and q, and use of pore pressure parameter, a, should account for the changes in the magnitude of a22O . octversus ct different. However, Fig. 5.18 shows that the ct Aoct) Oct Oct m [( oct ) m = vm ) from TC and TE tests are For both vertical and horizontal loading, the pore pressure parameter a from CIUC test samples is always greater than that from CIUE tests (Tables 5.4 and 5.5). Therefore, the increase in the magnitude of a2 decreases the pore pressure parameter a. The effect is more pronounced with vertical loading than with horizontal loading. The decrease in a is also larger in OC samples than in NC samples for both loading directions. Figure 5,17 shows the NESE at qf and (a/a 3 )max from the test series. These data and data in Fig. 5.7 show that NESE at (al/3)ma x for ent of: failure across the varves is practically independ- (1) the stress system during consolidation; (2) the intermediate principal stress; (3) rotation of principal planes; and (4) the magnitude of avm vm (limited data only; more data being presented in Chapter 6). It is stressed that the effects of the differences in the magnitudes of a2 and in the directions of Aa2 relative to the varve structure (perpendicular or parallel to the varves) shown from comparing TC and TE test data on vertical and horizontal samples can not be separated. be as important as the a2 . In fact, sample orientation might Thus, no definite conclusion regard- ing a2 can be drawn from this test series. 164 5.3.3 Results from K Consolidated Plane Strain and Triaxial Tests Figures 5.20 and 5.21 show normalized stress-strain curves of normally consolidated samples from CKoUC and CKoUPSE tests, and those from CKoUE and CKoUPSE tests respectively. The samples from the CKoUC and CKoUPSC tests reached the qf condition at a very low strain and the (1/a3)max condition at a large strain (Fig. 5.20). The CKoUE and CK o UPSE tests, on the other hand, reached qf and (al/a3)max simultaneously at much larger strains especially the TE test (Fig. 5.21). Normalized effective stress paths for these tests are plotted in Fig. 5.22. These data and the data in Table 5.6 and Fig. 5.23 show that shear in plane strain relative to shear in triaxial tests: 1. Slightly increased qf(V)/avc by 10%; 2. Increased qf(H)/avc by 20%; 3. Decreased Af for both vertical and horizontal loading ; 4. Decreased the shear strain at failure (Yf) computed from the linear elasticity theory (Table 5.6); 5. Increased E/v 6. Increased u vc (Fig. 5.23); (assuming c = 0) at qf for vertical loading (i.e,, PSC > TC), but decreased f c = 0) at qf for horizontal loading larger Pf/am (i.e., a TE> i PSE). loading, 5 at (1/03)max because of For vertical from CKoUC and CK UPSC tests are almost identical. It should be mentioned that because of the inherent problems with friction forces in the plane strain device, the results 165 from the plane strain tests may be questionable. Any frictional forces along the vertical boundaries of the rectangular specimen will affect the measured vertical force. Thus, the qf/avc and EU/avc measured from the plane strain test may be too high. In plane strain compression (PSC) tests, the errors in measuring qf/avc and perhaps Eu/avc probably are small because the direction of the major principal stress during consolidation and shear are the same. Because of the difference in loading direction during consolidation and shear, the errors in measuring qf/vc and Eu/avc from plane strain extension (PSE) tests will be more important. Despite having friction problems in the apparatus, the increases in qf from triaxial to plane strain tests for both vertical and horizontal loading agree with the other test data reviewed in Chapter 2. As shown in Table 2.7, data from Boston Blue clay (Ladd and Edger, 1972) show an increase in qf/avc from TE to PSE of about 20%. Data from Haney clay (Vaid and Campannella, 1974) also show the same increase of about 20%. Data from CKoUPSC and CKoUC on these two soils also show an increase in qf from TC to PSC similar to that for the Connecticut Valley varved clay. Regarding the measurement of undrained modulus, it is difficult, if not impossible, to make any assessment of the effect of friction forces. However, Boston Blue clay data obtained from using the same plane strain equipment show no practical difference in E/ c from NC CKoUPSE and CK UE tests, despite 166 having friction problems in the apparatus (Ladd et al., 1971). Since the increases in Eu/avc (Fig, 5,23) from TC to PSC and from TE to PSE are very large, there may be a significant effect of 2 on E/vC, though probably not as large as measured. The plane strain test sample also failed across the varves (though only the CK0 UPSC test developed distinct failure planes). Thus, based on the result of Section 5.3.2, the NESE at (al/a3)max for failure across the varves (shown to be independent of the stress system during consolidation and of the magnitude of a2) shown in Fig. 5.17 should be identical to that from the plane strain tests (Fig. 5,22), Figure 5.22 shows the NESE at qf and (al/a3 )max conditions from CK0 UC and CR0 UE tests together with normalized stress paths from CKoUPSC and PSE tests on NC samples. This figure shows that; 1. The magnitude of a 2 has little effect on NESE at qf and no effect on NESE at (A1/ 3 )max for vertical loading. 2. Test results from the CKoUPSE tests fall slightly from CKoUE tests max (also see Fig. 5.26) and from CIUE (=0) and CIUC below the NESE at (/a (8=90) tests. 3) This might be due to the fact that the envelope at high pf may not be a perfect straight line* and/or due to friction problems in the plane strain device. *Note that data from CIUC (=90) fall slightly below the envelope. 167 tests on NC samples also Since qf values for OC plane strain tests are not available, they were estimated as follows. qf at avc/qf at Figure 5.24 shows a plot of vm (equal to SR shown in Fig. 5.24) versus OCR from several types of tests, It is seen that for the same load- ing direction (i.e., either horizontal or vertical loading), the ratio qf at SHANSEP test. vc/qf at vm is independent of the type of Therefore, qf values for a particular loading di- rection at a given OCR for a plane strain test can be reasonably estimated by the relation given below. qf/vc qf/aVC of the NC sample x SRx OcR = (Eq. 5.3) Using values of SR for horizontal and vertical loading, Fig. 5.2.4 presents the calculated plane strain test qf/Uvc values from Eq. 5.3 and also the measured data from triaxial tests. Use of triaxial tests to estimate S will obviously lead to lower strengths than plane strain tests and thus presumably yield somewhat conservative results for field situations involving plane strain loading conditions. If one wants to obtain the estimates of plane strain qf values from triaxial tests, CIUC and CIUE tests on vertical samples seem to be the appropriate tests to perform. As shown below, the agreement in qf between CKoUPSE and CIUE tests is fairly good, while qf from CIUC tests are about 10% lower than those from CK UPSC tests, 168 .f/avc f from Vertical OCR -o CK UPSC 1 2 4 c from Horizontal Loading Loading -- CIUC 0.28 0.47 0.76 CK UPSE .25 .46 .75 .25 .44 .72 0.245 0.42 0.68 CIUE Note, however. that this approach may not be equally applicable to all varved clay deposits. Since NESE at (1/3)ma 3 max for failure across the varves is a material property (see Section 5.2.5 and later Section 5.3.4), it is believed that NESE at qf which is the same as that at (l/3)max from CKoUE tests should also hold for OC samples from CK UPSE tests. Furthermore, based on NC test data, NESE at qf when pf/sVm> 0.3 for NC and OC CKoUPSC tests may be slightly above the NESE at qf from CKoUC tests (though by very little). The estimated values of and c/vm vm for NESE at qf from CKoUPSC 0 tests are 160 and 0.080 respectively (versus = 0.088 from CKoUC tests). *= 14.50 and c/am Vm These NESE values will be used for the interpretation of anisotropic behavior in plane strain loading presented in Chapter 7. In conclusion, the comparison of NC NSP from CK o U plane strain and triaxial tests on Connecticut Valley varved claysgenerally indicates trends similar to those for other homogeneous clays. 169 5.3.4 Interpretation and Results from Special DSS Tests Problems with the DSS Test Since the state of stress of the sample in the DSS test is rather complex and only the normal and shear stresses on a horizontal plane are measured, the problems that must be considered in the analysis of DSS test results are: 1. The complete state of stress during shear is unknown; 2. The state of stress in the sample is not uniform. A uniform stress distribution is expected in the middle of the samples, but high stress concentrations occur along the edges of the samples (Duncan and Dunlop, 1969; and Lucks et al., 1972). Based on the above mentioned problems, uncertainty regarding the state of stress at failure is a major problem. Ladd and Edgers (1972) analyzed four possible assumptions which might be used for estimating the state of stress at failure.* These are obtained by assuming: a. That the applied stress system is one of pur shear, i.e., A b. = Aa 3 = ATh That the horizontal plane is a failure surface, i.e., Th = C. 1 Tff and Ovf = ff That the horizontal shear stress is the maximum shear stress in the sample, i.e., Th = qf and avf . = pf. d. The location of Mohr-Coulomb failure envelope. The smallest Mohr circle representing the state of stress at failure must then pass through Th and *Arbitrarily defined either at Thmax or at 170 f and be (Th/av)max tangent to the assumed Mohr-Coulomb envelope. Provided the failure envelope is known, assumption (d), where the location of Mohr-Coulomb failure envelope is used, is most reasonable. Based on the analyses performed on NC, CH and CL clays, using DSS (=0) tests by Ladd and Edgers(1972), the pure shear assumption yields qf values which are significantly larger than those from assumptions (b), (c) and (d). The pure shear assumption is only reasonable when the soil is assumed to behave like an elastic isotropic material (Duncan and Dunlop, 1969; and Lucks et al., 1972). Thus, this assumption is questionable and probably should only be used at low strains where the behavior of a soil may be nearly elastic. Interpretation of the Special DSS Data For this portion of the study, the effect of a 2 on NSP (qf/ avc' Af and Eu/Ovc) are shown by comparing NSP from special DSS, PS, and triaxial tests. NSP from CKoUC and CKoUPSC tests and f- rom a CKoUDSS(C) test on a normally consolidated inclined sample are compared for the study of the effect of intermediate principal on stress-strain-strength behavior in the vertical loading. For horizontal loading, NSP from CKoUE, CKoUPSE and CKoUDSS(E) tests are compared. The assumptions employed for the interpretation of special DSS test data are as follows: (1) During consolidation: The normal and shear stresses are applied to an inclined sample so that "Ko consolidation"* *True K consolidation can not be maintained because the stresses on he vertical sides of the inclined specimen can not be controlled. 171 is maintained during consolidation. Such a condition requires that the complimentary shear and normal stress be developed on the vertical sides of the inclined specimen. As a result, the consolidation shear stress on the inclined (a) plane, Tac avc (-Ko)sinecosO; and the consolidation normal stress on the inclined (a) plane, sc' (vc(Cose+K sin2 8); note that = is 450 in this case. Two separate assumptions are used, namely: (2) During Shear: the pure shear sssumption (i.e., assumption (a)) and that of the location of the failure envelope (assumption (d)). The first assumpResults. tion was mainly used to illustrate that it yieldsunreasonable For the pure shear assumption, the states of stress during and CK0 UDSS(E) test samples consolidation and shear of CKoUDSS(C) 0 are shown in Fig. 5.25. As a result of assumption (1), the origin of planes, i.e., the pole, of the Mohr circle representing the state of stress during consolidation is located at the point defined by the stresses Tac and a ac of the varves is 450. CT defined as pc , since the inclination a0 This point (-Fig.525(a:):)cou-ldalso be +a - and q q vc . For a compres- sion test, simulating a CKoUPSC condition, the sample is sheared by increasing Ta . Figure 5.25(b) shows Mohr circles represent- ing the states of stress prior to shear and those at failure. Upon assuming that the applied shear stress is that of pure shear, the origins of planes for the total stress circle (TSC) and the effective stress circle (ESC) at failure are located at a point defined by pf = Pc and qf for the TSC and at a point defined by pf and qf for the ESC. Thus, alf in the CKoUDSS(C) test acts perpendicular to the varves and the principal planes 172 are not rotated during shear. Therefore, based on these assump- tions, a CK0 UDSS test on an inclined sample should measure qf(V). In the CKoUDSS(E) test (Fig. 5.25(c)), the sample is sheared by reversing the direction of T . As a result of using the pure shear assumption, the pole of the TSC moves from the point defined by Pc and qc before shear, to the point defined by p = pf and q = -qf at failure. Thus, the principal planes in the CKoUDSS(E) test sample are rotated by 900 and alf is in the direction parallel to the varves. presumably measured qf(H). Therefore, the CKoUDSS(E) test From the above discussion, it is seen that the varved inclination of 450 is selected so that qf(V) and qf(H) could be measured, assuming a pure shear state of stress during shear. For analyses based on an assumed location of the failure envelope, a NESE for failure across the varves was selected (referred to as NESE assumption). Because of the uniqueness of NESE at (l/a 3)max for failure across the varves (i.e., it is a material property), it can be used with reasonable confidence for the interpretation of CKoUPSS(E) test data on a NC inclined sample which reaches (Ta)max' the maximum shear stress on the inclined plane, and (T /ao)max condition at the same strain. The experimental evidence supporting the uniqueness of NESE at (al/U3)max and thus NESE is given below. All the test data [pf/vm versus qf/avm at ( 1/a 3)max] pre- viously presented in Sections 5.2 and 5.3 are plotted in Fig. 5.26. It also includes data from two stress-controlled, iso- tropically consolidated drained triaxial compression unloading 173 tests (CIDC(U)) on heavily OC RECOMPRESSION, Northampton samples, developing distinct failure planes across the varves observing at the end of the tests (Lacasse et al., 1972). Figure 5.26 shows the following. 1. Results from NC samples from CIUC (=0), CIUE (0=90), CIUE (=0), CIUC (=90), CK UC, CK UPSC, CKoUE and, to a less extent, CK UPSE tests lie on the same NESE at (a-/a3)max for failure across the varves. Further- more, the same NESE at (1/a3)max holds for OC samples from the above types of tests. 2. Thus NESE at (a1 /a3 ) for failure across the max varves is independent of the stress system during consolidation and during shear. This is one of the two necessary requirements; the other is the fact that the same NESE holds for both NC and OC samples. 3. Though data are limited, NESE at (a1 /a 3)max for failure across the varves is also independent of drainage conditions (based on CIDC(U) tests) and the magnitude of Chapter vm (see additional data in 6). Since NESE at qf when Pf/vm> 0.3 from CKoUC and CKoUPSC tests are practically identical (and therefore, practically independent of the magnitude of A 2 ), the NESE at qf from CKoUC tests is thought to hold for practical purposes for both NC and 174 OC triaxial and DSS samples. This NESE will be used* for the interpretation of DSS test data at (T )ma x from the CKoUDSS(C) tests. At (T/o) max, NESE at ( 1/G 3) for failure across max the varves will be used. The suitability of the pure shear assumption can be evaluated by comparing, for both vertical and horizontal loading, qf/avc values estimated from the pure shear assumption to those from the NESE assumption and to those from the triaxial tests, keeping in mind that qf/avc from the CK UE test should be the lowest value (since A 1= A 2>Aa 3 in TE tests). Experimental Procedure The only portion of the special DSS experimental procedure J which differs from that presented in Section 3.5 is the method In this case, normal and shear stresses were of consolidation. applied to inclined samples. Upon using assumption (1) (the state of stress during consolidation), the magnitude of T c and ac were computed as follows: acC a= For = vc(c° s 2 Vc vc( + K o sin 2 8) - K o) sinOcosO = 450; avc =c he (IC + (C ac -Tac Eq. 5.4 Eq. 5.5 Eq. 5.6 I tzq. A -.. r- ID.4-,fq. D .D) Eq. 5.7 (Eq. 5.4-Eq. 5.5) Since both avm and K o of East Windsor varved clay were known in advance, it is possible to consolidate so that the "assumed" *Since the principal planes are not significantly rotated in the CKOUDSS(C) test, the independence of NESE from the magnitude of A 2 is the major requirement. 175 Ko consolidation could be maintained in every load step. For the purpose of preventing the sample from failing at low stresses, only ac was applied during the first three load increments (i.e., tac = 0). weight. Tac is applied to the samples by using dead Table 5.7 shows the load increments (and the computed values of vc and ahc) that were applied to the samples from the CK0 UDSS(C) and CKoUDSS(E) tests. It should be noted that small load increments were used to prevent excessive deformation in the sample. Experimental Results The normalized stress-strain curves from CKoUDSS(C) and CKoUDSS(E) tests on normally consolidated inclined samples are shown in Fig. 5.27. The CKoUDSS(C) test sample reached Tamax' presumably equivalent to the qf condition, at a fairly low strain and (T /a )max presumably equivalent to the (l/a3)max condi- The CKoUDSS(E) test sample, on tion, at a much larger strain. the other hand, reached the Tamax and (T / x )ma the same very large shear strain. condition at Hence, the CK UDSS(C) test behaved like a CKoUC test and the CKoUDSS(E) test had a behavior similar to that of a CKoUE test. Therefore, this similar be- havior suggests that the uses of NESE at qf for (Ta)ma tion and of NESE at (a1/a3) for (Ia/a)ma x x condi- are appropriate. Figure 5.28 shows Mohr cirlces representing the state of stress at qf/Ovc from the two tests determined from the NESE assumption. Values of qf/avc and Pf/avc from CK0 UC, CKoUE, CKoUPSC, and CKoUPSE are also plotted for comparison. The points defined by qf/avc and pf/vc from CKoUC and CK0 UE tests 176 tests fall almost exactly on the Mohr circles from the CKoUDSS(C) and CK UDSS(E) tests respectively determined from NESE assumption. O The pore pressure parameter, Af, for the DSS tests was estimated by assuming dated samples. a value of K (K = 0.68) for normally Table 5.8 shows how the values of Af are obtained. Table 5.6 presents the comparisons of qf/ vc (or Af and consoli- at the qfand(l/a 3 ) r ff/svc), Yf, condition from the triaxial, plane strain, and special DSS tests (determined from NESE assumption). These data show that for both vertical and horizontal loading: 1. qf/avc values from the DSS and triaxial tests are identical. 2. Af at qfand at (c 1/Ca3) from the DSS are roughly the same as those from triaxial tests, especially in the horizontal loading. 3. qf/vc values from the plane strain tests are higher than those from the DSS tests; Af values are also lower. / _ 4. _ ~ (assuming c = 0) at qf from the DSS and triaxial tests are equal (since NESE and qf are identical). However, from NC CK UPSC test is larger than that from NC CKoUC test, and from NC CKoUPSE test is lower than that from NC CKoUE test. B angles determined from Fig. 5.28 are 9 test and 1110 from the CK UDSS(E) test. B from the CKoUDSS(C) The small deviation in from 0° and 90° respectively indicates that qf values deter- mined from CKoUDSS(C) and CKOUDSS(E) tests could logically be 177 compared with those from CKoU triaxial and CK U plane strain test. The agreement between the special DSS and CKoU triaxial data for both vertical and horizontal loading does not mean that the states of stress in the DSS and triaxial test are identical and that the 2 has no effect on these soil parameters for the following two reasons: 1. avc from the DSS test may not be correct. The com- plementary shear and normal stress cannot develop on the vertical sides of the specimen, especially at the edges of the specimen. Consequently, the "computed" avc may be too large compared to that computed from considering no development of shear stress on the vertical sides of the sample, and vc "measured" from DSS tests might be thus, qf/vc f too small. 2. The use of 450 varved inclination is somewhat approximate, though it generally yields a larger (T)max to using 8 = 45+ Fj/2 for vertical compared and using = 45 - loading /2 for horizontal loading. (See data from two homogeneous clays reported in Chapter 2.) As a result, the agreements between Af and qf from the special CKoUDSS and triaxial tests may be fortuitous. For both vertical and horizontal loading, the decrease in qf/Ovc from CK0 U plane strain to special CK0 UDSS test could partly be the result of: 178 1. qf/0vc from the plane strain test, especially that from the CKoUPSE test, might be too high because of the friction problem in the plane strain device; 2. qf/avc measured from the special SS tests is too low because of problems in the interpretation of DSS test data. Mohr circles representing the state of stresses at qf obtained from the pure shear assumption are compared to the previous results and shown in Fig. 5.29. Although qf/fvc derived from the NESE assumption may be too low for both vertical and horizontal loading, qf/avc obtained from using the pure shear assumption is even lower. (Note that the same avc was used for computing qf/avc values for both assumptions.) For horizontal loading, the pure shear assumption gives a qf/avc equal to 0.19 compared to 0.21 from the CKoUE test. Since the latter value represents the minimum strength, the pure shear assumption is not reasonable. Eu/vc values at various applied shear stress levels (the applied shear stress level being equal to Aq/Aqf for triaxial and plane strain tests and equal to ATa/(Aa)ma x for the special DSS test) from CKoU triaxial, plane strain, and special DSS tests shown in Fig. 5.23 are based on the assumption that the soil is a linear isotropic elastic material. It is seen that only test data from CKoUE and CKoUDSS(E) tests show good agreement with respect to modulus. Such agreement, however, may be 179 fortuitous. For vertical loading, the special DSS test gave a much lower value of modulus than that from the triaxial compression test. In summary, the major findings from this section are as follows: 1. The agreements in qf/avc, Af and (c=O) of NC soil from the CKoU triaxial and DSS tests, for both vertical and horizontal loading, are probably fortuitous. 2. (since it is a material (a1 /a3 ) at The use of NESE, especially property), max for determining the state of stress in DSS tests is apparently fairly reasonable, at least compared to the pure shear assumption. In general, it is thought that NESE at qf, if not equal to that at (a1 /a3 ) max max is dependent upon the stress system. For the interpretation of the CKoUDSS(C) test, it is fortunate that NESE at qf from CKoU vertical loading tests appears to be little affected by the magnitude of Aa2 and that the same NESE at qf holds for both NC and OC samples. (Thus, NESE at qf, when Pf/avm> 0.3 from CK0 UC tests is thought to hold for NC CK0 UDSS(C) test samples.) These requirements are sufficient for an interpretation of CKoUDSS(C) test data, since the principal planes are not expected to be significantly rotated. 180 5.3.5 Summary and Discussion Tables 5.9 and 5.10 summarize the general effect of Aa 2 presented in Sections 5.3.2, 5.3.3, and 5.3.4. The important points that need to be further mentioned are as follows: 1. For both vertical and horizontal loading, the agreement of qf/avc and Af from CKoU triaxial and special DSS (8=450) tests are probably fortuitous. This is due mostly to inherent problems in interpreting DSS test data, especially those arising from the assump- 2. tion for computing ac vc The difference in the values of qf/avc from the CK UPSE and CKoUE tests on NC soil is somewhat ampli0 fied by inherent problems (friction forces) in the plane strain device. This error is, however, less significant when test data from CKoUC and CKoUPSC tests are compared. Despite the friction problem in the plane strain device, for both vertical and horizontal loading, the trends observed from the plane strain and triaxial tests are similar to those observed from other homogeneous clays (see Chapter 2), i.e., the effect of 2 is more pronounced in the ex- tension than in the compression test. 3. The behavior observed from the CIU tests is probably not mainly due to effect of the intermediate principal stress. Because of using horizontal (=90) samples, the effect of inherent anisotropy (defined 181 in Chapter 2) is included. of A 2 One of the directions acting on the horizontal sample is perpendic- ular to the varves instead of being, in every direction, parallel to the varves, as for the vertical sample. Although for both vertical and horizontal loading , the trends of qf from NC CIU tests are similar to those observed from comparing CKoU plane strain and triaxial test data, these trends might equally be explained by using different sample orientations. 5.4 EFFECT OF TESTING METHOD FOR SHEARING PARALLEL TO VARVES 5.4.1 Introduction and Method of Investigation For shearing across the varves, the effects of the stress system during consolidation and the magnitude of the intermediate principal stress on NSP were studied in Sections 5.2 and 5.3. In this section, the effect of stress system on NSP for shearing parallel to the varves is studied. The influence is shown by comparing results from two types of tests, namely: CIUC tests on inclined samples and CKoUDSS tests on vertical samples. The stress system differences between CIUC and CKoUDSS tests are as follows: 1. For the stress system during consolidation, the samples from CIUC tests are isotropically consolidated, while those from DSS tests are Ko consolidated. 182 (Note that one direction of the consolidation stress (" ) in the CIUC test acts at 450 to the varve strucc ture, while hc in the CK UDSS test always acts parallel to the varve structure.) 2. For the stress system during shear, CIUC test samples are sheared in triaxial compression, i.e., Aal> A Aa 3. In the 2 = DSS test, the state of stress during shear is close to that of the plane strain, i.e., A1 >AC 2 >Aa 3 , and principal planes are continuously rotated during shear Any difference between NSP obtained from DSS and CIUC tests (besides the inherent problem of interpreting DSS test data) could be the result of: 1. The influence of initial shear stress (Ko consoli- dation); 2. The effect of intermediate principal stress; 3. The effect of rotation of principal planes; and 4. The difference in the relative direction of respect to the varve structure. 2 with One of the A 2 di- rections in the CIUC tests on inclined samples is 450 to the varve structure instead of parallel to the varves as in the DSS test on vertical samples. These factors could affect qf though their effects on the pore pressure response and/or on the failure envelope. The direct simple shear test has a problem with respect to interpretation of the data. However, the study in Section 5.3.4 showed that a NESE could be used to determine with reasonable 183 accuracy the state of stress at failure in DSS tests. Thus, value of NESE at qf and (al/a3) for failure parallel to the max varves are needed (since DSS samples at OCR's between 1 and 4 do not reach Thmax and (h/v)ma x at the same strain). The correct selection of a NESE requires that it -be a material property. Based on the undrained test results from shearing across the varves, this is only true for the NESE at (a1l/3)max or for NESE at qf when it is identical to that at (a1/3)max qf, when it is not identical ent upon the stress system. to that at (a1 /a 3)maM NESE at is independ- Therefore, the location of the NESE at qf for a conventional DSS test is not known for sure. interpreting thest data at Thmax For the NESE at qf for the appro- priate range of Pf/avm from CIUC (=45) tests is first used. The sensitivity of qf to variations in the NESE is then studied. For interpretation of DSS test data at (h/v)max' the uniqueness of NESE at (a1 /a 3 )max for failure parallel to the varves should be established. For this purpose, NESE at (a1/a3)ax from CDDS tests (the envelope being determined assuming Th=Tff) and from CIUC tests on inclined samples are compared. It can probably be assumed that, apart from the difference in the drainage conditions, the stress system in a CDDS test is similar to that in DSS tests, though the latter has a more uniform stress distribution. 5.4.2 Results from CDDS and CIUC Tests NSP from CIUC tests are summarized in Table 5.11. The test data from CDDS tests on samples from Northampton (Lacasse et al., 1972) where failures take place in the clay layer are 184 presented in Table 5.12. qf and pf were computed by assuming that the horizontal plane in the direct shear test is the failure plane. Consequently, qf is equal to Th/CosT and pf is equal to avc + Th tanT. The value in Table 5.12 are those re- ported in Lacasse et al. (1972). For shearing parallel to the varves, the samples could fail either in a clay or a silt layer. However, for the range of OCR's under study (1<OCR<20), observations of CIUC (0=45) test samples at the end of the tests indicated that the failure in these samples took place within a clay layer. (Hence, the fail- ures in the DSS samples are also assumed to be within the clay layer.) Consequently, the NESE from CDDS test samples which have failure within the clay layer is compared to that from CIUC tests. Figure 5.30 shows the NESE at qf from CIUC tests and NESE at (l/a3)max from CDDS and CIUC tests. Figure 5.31 shows NESE at ( 1 /; 3) of both NC and OC samples -from CDDS and CIUC (8=45) tests at high stress. (al/a3)max from It can be seen that NESE at these tests are identical (Fig. 5.31). Thus, provided the assumed state of stress at failure in the CDDS test is correct, NESE at (al/'3)max (Fig. 5.31) for failure within the clay portion of both OC and NC samples is independent of: 1. The stress system during consolidation; 2. The stress system during shear; 3. The drainage conditions; 4. The magnitude of a (samples from CDDS tests have vm different among themselves and from CIUC (=45) 185 test samples). Consequently, it is a material property. Therefore, it will be used to calculate the state of stress at (Th/ v)max in direct simple shear tests. For interpreting the DSS test data at Th, both NC and OC, the NESE obtained from CIUC (8=45) tests at OCR's equal to 1 and 4 will first be used. This is line D in Fig. 5.30. is assumed to be linear for Pf/ma CIUC (=0) 5.4.3 It > 0.3, based on data from tests at OCR = 1,2, and 4 (Fig. 5.8). Results from CKoUDSS Tests and Their Interpretation Three representative normalized stress-strain curves from CK0 UDSS tests having OCR's of one, two, and four, are shown in Fig. 5.32. The determination of the state of stress at Thmax of these samples is shown in Figs. 5.33, 5.34, and 5.35. Mohr- circles representing the state of stress at qf of inclined samples from CIUC tests are also shown for comparison. plot at (T /ov)max are shown in Fig. 5.36. The corresponding Table 5.13 presents a summary of the results from Figs. 5.33 to 5.36. These results show that: 1. At Thm , as the OCR increases, Thmax/Tff increases from 0.9 to unity at an OCR of four; 2. At (h//v)max Tff is equal to Th; 3. The horizontal plane in the DSS test is not a failure plane (this being true at both the qf and (/ 3)ma x conditions); 4. At Thmax, 8 increases with increasing OCR from about 300 to 370 versus 186 450 if Th = qf; and 5. At (h/av)max, 8 is approximately constant (370 + 20) and is thus independent of OCR. The angle 8 corresponds to the computed rotation of principal stresses. Since the principal stresses are continuously ro- tating during shear, the amount of rotation will depend upon the magnitude of shear strain. Hence, samples that fail at larger strains should have a larger . This only applies to the'hmax condition where in Yf increases with increasing OCR (Fig. 5.27). Consequently, $ follows the same general trend. At (Th/av)max Y is quite variable, but also very large and thus OCR has little effect on 8. The sensitivity of qf values to the location of NESE is evaluated and presented in Fig. 5.38. Three locations of NESE (arbitrarily selected X and Y NESE and that from assuming a horizontal failure plane) were used to compute qf/avc' Tff/avc and 8 for DSS samples at OCR's of one and two. These computed values are compared with those from using the CIUC (8=45) NESE, also presented in Fig. 5.38. As shown in Fig. 5.38, it is seen that: 1. The differences in qf are within 15%, the lowest value of qf being computed from the lower limit of NESE (i.e., that assuming a horizontal failure plane). qf values from NESE X and Y are within 10% of those determined from the CIUC (=45) 2. The values of NESE. vary with different assumed states of stress in the DSS test. 187 The fact that' c=O0)for NC soil determined from this horizontal failure plane assumption is unrealistically low (=15 and that the computed °) value is significantly different from the X, Y, and CIUC (8=45) NESE shows that the use of a horizontal failure plane assumption is not suitable. 3. The small variations in qf and 8 determined from using NESE X and NESE Y suggest that the use of NESE from CIUC (e=45) test data for interpreting the DSS test is suitable and much better than the use of horizontal failure plane assumption. In general, Th is not equal to either ff or qf. Ladd and Edgers(1972) concluded that they would expect Tff<Thmax<qf. Based on the results presented in Table 5.13, Thmax can be up to 12% less than Tff for samples which have OCR's of 1 and 2, and is approximately equal to Tff at an OCR of four. data suggest that the use of hmax as the value of undrained total stress analysis will These ff in an be conservative, especially at low OCR values. In summary, the use of NESE from CIUC (=45) tests leads to a reasonable interpretation of DSS data at the Thmax and (Th/av) condition. Thmax values of samples at low OCR are generally lower than ff. As the OCR increases, the ratio Thmax/Tff approaches unity. 5.4.4 Comparison of Results from CIUC (8=45) and CKoUDSS Tests Table 5.14 presents a summary of NSP obtained from CIUC 188 tests on inclined samples and CKoUDSS tests on vertical samples. qf and Af from DSS tests were determined from using NESE at qf from CIUC (=450) tests. The results in Table 5.14 show that shearing in a triaxial condition relative to a DSS condition: 1. Increased qf/avc by about 10 and 20% at OCR's of one to four, respectively; 2. Increased Tff/Ovc at (/a3)max by about 20+5% at both OCR; 3. Increased Af at both qf and (l/a3)ma for nor- mally consolidated soil, but decreased them at OCR = 4. As previously stated, the differences between NSP from CIUC (8=45) and CKoUDSS tests could be the result of several factors. Based on the comparison of the stress systems in these tests, it can be hypothesized that such differences are due to the rotation of principal planes, the intermediate principal stress, and the initial shear stress effects, as well as inherent problems due to the interpretation of DSS test data. In summary, the use of SHANSEP CIUC (80=45)test samples for measuring the in situ qf for inclined loading will not be conservative. The analyses presented in this section also show that the use of NESE at qf from CIUC (=45) tests leads to a reasonable interpretation of DSS test data, at least better than using the assumption that the horizontal plane is the failure plane. Because it is a material property, NESE at (al/a3)max for failure within the clay layer can be used 189 with confidence for interpreting DSS test data when the Th and (Th/)max conditions occur at the same shear strain (e.g., in heavily OC SHANSEP samples or OC RECOMPRESSION samples. 5.5 GENERAL DISCUSSION One outcome from the studies of the effect of stress sys- tem on NSP is the opportunity to investigate the possibility of using a simplified testing method for evaluating anisotropic Su values for total stress analyses. The CIUC test is the simplest test and could be performed on vertical, inclined, and horizontal samples. Therefore, data from CKoUC, CKoUPSC, CKOUDSS, CKoUPSE, and CKoUE tests will be compared with those obtained from CIUC tests on samples with different varve in- clinations. Figure 5.39 shows plots of qf/avc versus OCR obtained from these tests. The data from CIUE tests are also included for the sake of completeness. It can be seen that the stress sys- tem during consolidation and the intermediate principal stress have practically no effect on qf(V). Therefore, CIUC tests on vertical samples could be used in practice for measuring qf.(qf from UC tests are about 10% lower than those from CKOUPSC tests.) CIUC tests on inclined and horizontal samples, however, can not be used in place of CKoUDSS and CKoUE or CKoUPSE tests, since qf values from inclined and horizontal loading are significantly affected by the stress system and/or sample 190 orientation. The combined effects cause qf(H) from CIUC (8=90) tests to be up to 35% higher than those from CKoUE (=0) and about 17% higher than those from CK0 UPSE tests. ferences are rather large and, hence, CIUC (=90) not tests The dif- tests are suitable to use in practice for measuring the horizontal undrained shear strength. For inclined loading, qf from CIUC (0=45) tests can be 10 to 20% higher than that from DSS tests (Fig. 5.39). Such a difference is also somewhat too large. Thus, in practice, CIUC tests on inclined samples overestimate the strength for the measurement of Su with inclined failure surface. The above conclusions are based on the test results from SHANSEP samples. For RECOMPRESSION samples (see data in Chapter 6), CIUC tests yield a reasonable value of qf(V), but qf(H) is too low at the in situ OCR of 4 because of disturbance due to separation of the varves. On the other hand, qf(4 50 ) from a RECOMPRESSION CIUC test is practically equal to qf from SHANSEP CK0 UDSS test, though this may be fortuitous. 5.6 SUMMARY AND CONCLUSIONS The principal findings from the study of the effect of stress system on NSP with different loading directions using the SHANSEP method of consolidation are as follows: 1. For vertical loading, the stress system during consolidation and the intermediate principal stress have little effect on qf(V). 191 However, they affect Af, f, Eu/avc, * (c=0) of NC samples, and generally NESE at qf, though NESE at (a /a3)max is not affected. (See Section 5.2.5 for a de- tailed summary of the effect of stress system during consolidation and Table 5.9 for the effect of a2 .) 2. For horizontal loading, the stress system during consolidation and the intermediate principal stress affect qf, Af, f, E/avc, 4 (c=0) of NC samples, but have no effect on NESE at qf (same envelope as that at (/a3)max) (See Section 5.2.5 for a de- tailed summary of the effect of the stress system during consolidation and Table 5.10 for the effect of a 2 .) 3. Limited data show that the stress systems during consolidation and shear affect NSP from inclined loading more than fromvertical loading. 4. The stress system during consolidation and the intermediate principal stress have more effect on the horizontal undrained shear strength behavior than on the vertical undrained shear strength behavior. 5. For vertical and horizontal loading, the NC test data from CKoU triaxial and plane strain tests, show trends similar to those observed with homogeneous natural clays (reviewed in Chapter 2). Due to inherent problems in interpreting DSS test data, especially the assumption used for estimating 192 avc value, qf, Af, and 4 (c=O) for NC samples from the special DSS tests on inclined samples may be fortuitously identical to those from CKoU triaxial tests. 6. The use of strength data from CKoU triaxial tests rather than plane strain tests for the evaluation of aniostropic S u values for total stress stability analyses in plane strain loading should be conservative. Also, the use of Thmaxfrom tests as Tff 7. seems to be conservative CIUC tests on samples cut at DSS (=0) as well. =45 ° and 900 will yield unconservative values of qf for undrained total stress stability analyses, though qf(V) from CIUC tests are slightly lower than those from CKoUPSC tests. 8. Reasonable estimates of qf(V) and qf(H) for PS conditions can be obtained from CIUC and CIUE tests on vertical samples. The results in this chapter also provide insight into the basic understanding of the anisotropic behavior of varved clay, as presented below. 1. There are four possible failure mechanisms in varved clays, namely: failure by developing distinct failure planes across the varves, failure by bulging, failure within the clay layer, and failure within the silt layer., 193 2. Despite failure by bulging in CIUC (=0) test samples, their NESE at (al/c3 )max is identical to that from CK UC test samples which develop disO tinct failure planes across the varves. This indicates that the basic failure mechanism (i.e., failure across the varves) is the same even though bulging occurs. 3. The NESE at (a1 /a3) ax for failure across the varves and for failure within the clay layer are shown to be independent of: a. The stress system during consolidation; b. The stress system during shear; c. The magnitude of av vm (see additional data in Chapter 6); d. The drainage conditions (limited data); and e. The OCR of the sample. Therefore, these envelopes are considered to be material properThe values of ties. and c/avm of these envelopes are given below: 5. c/avm 0 Type of Failure Across the varves 30 Within the clay layer 22 0.017 0.027 The NESE at qf, if not equal to that at (l/a3)ma x (e.g., for vertical and inclined loading), is dependent upon the stress system. For vertical for failure across the varves is much larger *Note that than that for failure within the clay layer. 194 loading, the NESE at qf, when pf/a > 0.3 from CKoUC tests,is lower than that from CIUC tests (Fig. 5.8). Results in Sections 5.3.4 and 5.4.3 suggest that appropriate values of NESE at qf and (a1 /a3 )max can be used to interpret the results of DSS tests, and that is much better than using the pure shear assumption or assuming a horizontal failure plane. 195 EXPERIMENTAL PROGRAM FOR INVESTIGATION THE EFFECT OF STRESS SYSTE-MON SHANSEP NSP Stress in kg/cm2 Variable Type of Tes0 Test CIUC 0 EA 1,2,4 4.0 CK UC 0 E,A (2) 1,2,4 3.6 to 4.0 CIUE 0 E,A ( 2) 1,2,4 4.0 CK UE 0 E,A (2 ) 1,2,4 3.6 CIUC 0 E 1,2,4 4.0 Intermediate CIUE 90 E 1,2,4 4.0 Principal CIUC 90 E 1,2,4 4.0 Stress CIUE 0 E 1,2,4 4.0 CK 0 UC 0 A 1 CKoUPSC 0 N 1 45 A 1 CK 0 UE 0 E 1 CK UPSE 0 N 1 45 E 1 45 E K o versus Isotropic OCR OCR vm () L) _- Consolidatio CK UDSS(C) CKoUDSS(E) Effect of Testing Method CIUC Testing Mt:'d for Shearing Parallel to theVarves Notes: Soil S Location (1) (2) 2.99 to 4.0 3.6 to 4.0 1,4,20 4.0 CK UDSS o 0 A,N,E 1,2,4 3.0 to 4.0 CDDS 0 1,1.83,3.4 3.4 to 6.0 N E = East'Windsor; A = Amherst; N = Northampton Only soil from East Windsor that are tested at indicated OCR. Table 5.1 196 00 O oo H 0 ,- 0 H _ l l '.I - -4 O c~ c o H O H O O O O o O 0 kD cO c0 LD N i Ib -i O O O- O N rO O Is NCd H) 0 - %- IOE r_ O O O 0 O 11- C) C U H H H E) e Cd H .- -H (N H ,, (N H; C 44 Cd c) N, LA a% 0* ,4 4 O _ IN N H w sw E-i En O +1 N N 0 44 U) Z 4I 43 o 0 (d -P U p1 u C3 I U) t) 0 00 0 O O 0 0 o 0 N C (N 4 > Cd 0 _-- o -1*, o UO Ln L1 10 N H (N U)H OI 0 N0, O 3 O O .- i - .) 00 o (N +1 Cd H +1 00 O0 ..f H C) 4U 0V o Cd U) z ) 'O 0 N 4 +1 r-i 0 H 33 H 0 o O U) Im w 0 I ) H H 0 'II----- - Z * m Cd U O H It +I g rd id 1-1 Ln ,C 4\ a) X O Il 0HQ o U) co O +1 aId oH H >4 +n 0 o+1 o LO v ,r- ,4 o t O0 L) , 0 co LA i+1 * N 0O N H CV Ut) U1 o (1 OI uL 0 44 Ib 44 tr O O O * o +1 +1 O 44Cd o 0 o o -!. O LA ', o+o o o 0 o - +1 .- vI o 0) o - 43 H4 H E1 E- v (N r-q tU )~4H /dIO -u Ir") 30 D: U Y H OI u ----- z0 - iU 197 _ _ Table 5.2 a4 B M Ur H * o o M IC! It or- r- 0 0r- 0 0 0 ti U -e lb n N mn c iaI Hn 0 m3 0c 04 43 r II- r(-- - c, 0c 0 4.' 0 a 1 4) H H H I. lb lb v j~ dA V 0 u 00 0I $ ao cn C) *Nl 0. 'r4 :' 4 o id o_O · o,,el Co L N · O oa' O O 0 VX0 O3-4 O :A 0 'U N S .o I- c> F -.CO 4 Ln 0 I11 UI . oC. l o L . Ln 0U O n .t H4 H 94 0 0 H 0 H ., * E., S > . z 1 E- ar Ci H Ci , N. < 4 198 Ci i i a Table 5.3 - __ - I 4) O: kI > 0 4 m I) ~ Cu O r-- - N 0 E- U C14 co \ (d r-III H E4 I- 0 0Om o o (% 0 L 00 ' '~e (' ·L_Yr Y Y1_·__· u I· I U OZ H En E- 0 EI 0 0il o O o o O O Ln UI o o ,4 o O o eel oCe o - C O O o o 0 4 Ib - _n _ I 9 m -I _j Ib H O b I f-4 bH --,- 0 - · -i Ln m N o O oI 0L H o HI N 44 r-i. O - > 44 4)"4J b> .)- oO 0 _II I4 co H o o 1O o lb m 0 o O - g r. o H r- O o II r r- IU 10 o r- C; I - - O Ln O C N - LA N co00 H r O O O I 0 N O H. O O O _l N LA tD u* D * %D m H0 4-4 .0 > o *. dPrH< 4) Ln 4 4 1W 0 N N o o o o N N 0Or O H H H r 0 ii. O O II -H O 11 11 0 oo H Iu1oI E- O oH-i v 4J II- o N oa 0 - N o CD U O I O0 C; OZ r--I 044 Ln ! ! 0 O * 0 e "I O N 4e _ H4 N 0~ u N I O L I 0 r0 -i ,H N O oO IL L ,Z o i o L o o o o 0 0 - O oI I IVr oOIn 0 z N n A - C; II 0 * I r H 19 H I I U H M I H H I m I rl m I I I I Ez U H H H W p I4 I H I 199 I r-I Table 5.4 0 EO v) > E-' H EU (d 44 U Ln Lo Fr3 - Z U E zZ 10 H I 1 o o o o o o o o o Lr) qc 0 OI om GO I 00C o O o O I I H- rH x1 (n N H (a wl a 0 t-41 N H 4I o dP '.0 o o o H w >4 IU 4 o IH 1 o N ,D 0 N 00O oo oo oo oo o o um >4 Ln >4 o c* 0O D U) o o o o oo 0o o I O O . H O b) U)Lr c. CO O o o Lr 1* 1* o * a4 H r- r- I3 1x4 H 1> U H o ;o co o Eu Oa I 0 o U . L r, o 0 o LA 0 o oo' o LA 0p N . . HU ) 43 -.->Oo a) ..0 . . . . .-- 4 . E U u CIr D H . 04 + N- I 4 H rXI I . I U H 0) 01 43 J ... N ur H U IH I I D IH IU IH I 1 I I IU H I H N m 0 Iu . I o U ol-lo D N EO4J '. LN 4-4 10 0 0 H v o Co Cn H nr o o m o Eu o H oo oo P: U 0H o ') z 0 t0 H o N O N II 0 0 u H o z0 - H m I H H U H - U W 94 W w .m U) 43 0 2n "nF ' 'UU Table 5.5 __ - - o N CN U) (0 N N H U) E- O oo O C00 N O CN *~ * 00 *~ * a) .4- I N 0 U) I- I cro U) Ib a .-l4b l - O N- N LO 4 c4 Co 0 0 44 4 H f- N H 1 0O H U) H U >4 4 0H0E- -3 D) 4I IC tJ 0 O ,Z O 5 U N-\ N o 00 0 0 o- O O onfl L. _ U) 40) .i t", eOi r1 emO .. r !1 Lr LA 00 L) Co O L4 H Ln O 4.) J-) N ooO Co, CeJ . . O 1 O H 0 N em e O 00 O CN N 0 m S O )U H ,4 , N kO O O o H 4.) 4 U) U) I o crj U) (u -II rm g 1t4e It ro1 HC IO + 0 0 b ea c 0 tq N . O0 0 10 , o0 oCO Uo O 0 0 0-1 N , . H O4 Ilb () > 9r 00 * i-e- H CO 0 nn oo N- s __@ _ r N or- Ln 00 On o 0 , C xit w H 03 W aU) N n· O U) r- H H z O m Xtt, I C) . >iO4 U) 1o o >)E E>1 0oao t r40 II H 1 i 4 j H I c uH _ QU) IoO l0U-Io tUIO k4 4. > w (n 4-.) tqU) M U4) EH Z HI I U X U P 4 0 H 1 Table 5.6 aU 201 LOAD INCREMENTS USED IN CKoUDSS(C) and CK UDSS(E) TESTS ON NORMALLY CONSOLIDATED INCLINED SAMPLES ac 2 = aV (cose + K VC(1 - K TC= ) 2 sine) sinecose Stress in kg/cm2 OCR OCR Ko | T Tac I: ac | ahc vc 23 1.0 0.104 0 0.104 0.104 11 1.0 0.211 0 0.211 0.211 4.6 1.0 0.520 0 0.520 0.520 2.36 0.91 0.971 0.049 1.016 0.927 1.61 0.80 1.342 0.146 1.488 1.196 1.133 0.74 1.838 0.281 2.119 1.557 1.0 0.68 2.097 0.399 2.496 1.698 1.0 0.68 2.505 0.479 2.984 2.026 1.0 0.68 3.020 0.575 3.595 2.445 1.0 0.68 3.395 0.639 4.034 2.756 For e = 450: avc = sa c + c and hc ac - t eac Table 5.7 202 ESTIMATION OF Af FROM DSS TEST SAMPLE (8= 45) NESE ASSUMPTION USING o-f oc AC' \\ - at Qo rm 'i _ _ _, _ 'A &,, _ 4-- from e¢u cation Assuming two dimensonalo/ applied stress systemn = A %f-A af , f - c O. I At, ,, 'o, - 2 f /( =,) / { a .- 2 AUf: c = - 1C 203 2 E4.S.9 Eq. .// Eq. 5?/O *(zIC) 2 A:/f Z III Eq.5/2 Eq.5./3 io7 DSs test TABLE 5.8 _____ L ______ ___ 4.4 x N x 0 x a 0 m .4 E __ m 103 Z H X X -) - a) 4 Z - - 0 _II - - >1 o 0 r-4 0 Cd a .4. Cd I 11 I .4 tr 0 . rF-1 z 0 .Q > H t- .-1. > 0 C-- Z 0 .rq EO ,4 0 H *, a) 4J 0 .U) U) c 4 0 H x X 0 x U) -K U _X vr * X - a U) 4 U o I +1 0 d 0.4 U a) x 1) Cl) rX E-4 .7-4 4- Cd a) N Cd - U dP I- 4 dP Lf 44 N 0 H- 0 Cd U) 00< 0 aC pt a) .4 4.0 .ri 4 4 00 o O4%U) 0 a) o E- 0 4IC. 4z -H UriC1WH *,-C1U) H> E-4 . 3 H U t-10 ro N ) a 4 u co U0 U - -. a P rO r-H 4 .. H X 7-4 N m 14,LnO 1-1 I . .- -i . - U) COC P4UU) a) 3U : H U t 0 W k O U)cn ) U IUu ~~ ~ ~ ~ ~ a)C a 3 a) 4 o U0 U.r-f-- z0 m0k U .. 204 A Table 5.9 4-4 0 0 to C ro 0 Cd 44 44 4.) 0 to 0 01 4-4 ,-I H tdX m Zlb H P; 0E-, Cd Cd W m t m Zlb al o .) 0 0 54 Cd - W~ cU) 0 X (d f W U) EUl cl U) 0 Cd 0 E CdX Cd 0) Z 0 (D Ut .14 44U) 4) 0 4-4 4-4 x ,/4- U) 0 Zi H -10 0°l x X X 0 O Ib Cd X X 4r 0C.d -U 0 4O X E -H 4-4> WH 0 C.~h {J 0) 00 r- 14 P4 dP 0O to ~) - t-,4 N O0 a) 0 U) tn U) It -H C D Q)-H U) a) r O 00) N ( o) o+I QU) N -*I *4 .c OCd C -Hr . r4 0)4 b 0,l 0 U 4-1 U( o rn c Hl p E 0) E-4 _ - 3CDk 13 4J ,,, O 3 N M) Ln U) U) U)En U U OQ) U 0 U 205 0 z Table 5.10 dO (A) w 00 o r o a\ O 0 ·J o (N o0 L) Ln 0 InL (N LO LA r4 C3 r-4 X i0 r4-4 No 0 Ln o I0 LII 10 11 C4 IO I-, 10 0 H U zHz O 10 "I,, 0 wW r)P X E- E 53 O I1 O O O H 00 r (N 00 H10 mo 0 CN 0o 0 L LA 0 un mr L LA or (N n Ln m (N 0; 0 H o rl LA H 44 0 1 . I 10.1 1 b v 01 H O I1 n r- o gI 10 H U) O C0 -I.0 .* H r4 r-i (n o 0) 0 (N (U) 112 E4 3 0 .C* H e C4 0 (N 0 C,) a) IC En 'r W UA H Table 5.11 I (N E-4 uI U H F1 IIC)( (N N (N I I I U H N U H w C) H r 206 RESULTS FROM DRAINED DIRECT SHEAR TEST ON NORTHAMPTON VARVED CLAY FOR FAILURE WITHIN CLAY LAYER (LADD AND WISSA, 1970 AND LACASSE ET AL., 19-72) Test N. Test __ aT ah TSF TSF (1) vc (2) qf (3) q(1 ciqvc _vmvm NCD-5 3.65 2.00 0.380 19.50 0,410 0.220 0.620 NCD-6 3.4 1.01 0.495 19.50 0.525 0.160 0.350 NCD-1 4.0(4) 4.0 0.385 21.00 0.410 0.410 1.150 NCD-2 5.0(4) 5.0 0.390 21.30 0.420 0.420 1.150 5.14 0.450 24.1° 0.490 0.490 1.220 6.00( 4 ) 6.00 0.340 18. 8 0.360 0.3.60 1.120 NCD-314 NDC-4 Notes: (1) From Lacasse et al. (1972) for overconsolidated samples: = tan 1 h for normally consoli- ovc dated samples. (2) qf/avc =(Th/vc) (1/cos) (3) Pf/vm = Th/a vm tan + °vc vc vm (4) Laboratory maximum past pressure (a m(L)) Table 5.12 207 0 cc S4 r HU .cl 0) U H) 4-) o o z o r oN 0 LH 0 H H 0 Lr) A c Ln 0O o 00o O m H o Cd - CNI Hf O LO x rH .H 010 0 U) o4 a) 10 n EU) 4) E- 41 U p4 IO> U) cn u 4tlc> a: m o 0 0 0 0 c7 (v-) r- D H N o U Clu 0 N- i4 c 01I ¢· UltT3 LA N- x Cd -i tlD 0 0 00 o 0 0 L; LA d 0 c; oN o HI. 0 o Lo LO H 0 o En U) 4a) 4-) z 0 *,{ m {.o 4-4 0 t .......... E- U co X- Q a 0U) 44 Cd U) WH W U) . z rd .a) U) r., -r1 1-~4 ) a) -It· m P·ltC Ln O O M Iti rd .f-e -H0 ·- kir 4 1,C I >3 U) Wt r- - -- H r-q o v o cn 0 (N C4 _ 0 M V) a) 4) U 0 H N R O Z Table 5.13 208 0H I .- x C) I t, 1tHm N) 'o H Im - l cd H N HI H:1 I o 0 m 4t V) I.... O N . o 0 x H ib 5 U) W>0 Igu W '1bt Co H . E 4 o rl 44-4 1U Cd 0 -4r-i 'u UL m O 0 o 00 o O O U) . O o H 0 N H o 8W \D 4-4 zH Ul 44 U E4 I-r E-1 IEb XI B _cn W 3 0 bU 'INI U) rI H Q) 4U.4J 4 a u]-' 0 U u O U 0 0 Cl) z j - O U N H H N I U U) U U) H Q N N 4.) U) E-I z Q) U H U U H v N H 0 H Table 5.14 209 0 2 4 6 8 /0 AV V /2 _ /0 -- Dat rom 3 C/; N =-56.9 .0'% /4 _ Daoto from /6 CKo U tests; wN '= .3 O.7 % _ /8 _ 20 _ I4 _ '21L O.I -~~~~~~~~~ i O.Z I I 0.4 I B 0.6 I I 0. I B /.0 I I 2.0 o &'vc, kg/em2 VOLUME CHANGE DATA FROM I clu AND CKoU 01I SAMPLES TESTS ON HORIZONTAL VARVE (8: = FROM EAST WINDSOR 210 FIGURE 5.1 .0o L a~~~~~~~~~~~~~~~~J a rl TEST K -/I, AMHERS7 MA. /Ist Unload from 8 2 7tf to OCR=32 18 - 0 Reload to 20.5 Tss O 2nd Unload from 20.S TSF wN = 60.4%,El. /07 ft / / / / / / / // / 1/ 12 / / /, / / _ / / / / / 1.0 _ / / S/ / / _^ _ , Relatio.s*i 0/ -·i -irecomn endea p / ~f /0 0. 0.1 I I A I 3 I 4 I I I I Ii 5 6 7 8 9 /0 20 OCR Ko VERSUS OCR FOR CONNECTICUT VALLEY VARVED CLAYS 211 FIGURE 5.2 0.8 OGR / 0.6 _' 4. - - -a s 0 ) v *v c C TTs NO / 0 I 0 2 I 4 I SYM. TYPEOF ar yc TES oY | rEs T rT g/co . A/C-I -/ 0 C1IC AKC-/ * CK 0L/C2.99 187 I 6 I i, I 8 /o AX/AL S TRA/N, 4.0 I .90 I 12 % h NORMALI ZED STRESS-STRAIN DATA FRO M CIUC AND CKoUC TESTS ON NORMALLY CONSOLIDATED AMHERST VARVED CLAY 212 FIGURE 5.3 /' r. 1.6 pr 5vc 0.8 vc LAB. ' OF -ST 7c /.0 4.o 0.4+ 'oc I.0 40 ,I 0, &;m K9/a 1 I 2 I I I 4 I I 6 I 8 AXIAL STRAIN, I I , I I /0 I I I 12 qa% A - AXIAL STRAIN, Ea % NORMALIZED STRESS-STRAIN CURVES CIUC AND CKoUC TESTS ON OVERCONSOLIDATED (OCR.=4) WINDSOR VARVED CLAY 213 EAST FIGURE 5.4 14 Af OCR (a) VERTICAL LOADING OCR (b) HORIZONTAL LOADING Af VERSUS OCR FROM CIUC, CKoUC, CUE, AND CKoUE TESTS ON CONNECTICUT VALLEY VARVED CLAYS FIGURE 5.5 214 o /s o10 % ,5 0 / 2 (ao) VRTICAL '5 4 s 6 7 OCR LOADIN6 I ()/"a1 ore identical t fI"-c)mzox and (a& ~~-,/ o Ef /0 3 1-- E%I 0 o C/uE * CKo IvE I i· 3 2 I· 4 I· J ·I 6 7 OCR (b ) HORIZONTAL LOADING Et VERSUS OCR FROM CIUC, CKoUC, CIUE, AND CKoUE TESTS ON CONNECTICUT VALLEY VARVED CLAYS 215 FIGURE 5.6 0 I- ROZ ZO ,) O -J I U)z O I _4 Lz b 4. 0z I,- L.I -o 0 w z aO --j -.I 0 x 0 2o 3: 0 zw C:3 Z ,b'l4 216 Ib" 'l FIGURE 5.7 C/) IL O w cn > > > b W . -Jw en ib W __z oWO . w OW. M Nw w C Z N zTo P) a, ' e 217 l 0 FIGURE 5.8 4000 - I TYPE OF OCR NO. OF S YM 3000 _ 0 2000 I l w TES T TES TS clUc / 2 4 2 I 2 2 Ck'ouc - 0 Uo CkoUC / /000 _ 700 _ 500 E,, 9f _ 400 .00 _ O\~ 200 _ ) OCR from CIU tests ( /00 _ £) OCR from C/4ot tests J, 0 an " I I I a6 0.4 CI 0.8 /.0 a 9 Eu VERSUS qf ON SAMPLES Aq Z-qfFROM CIUC AND CKoUC TESTS L~q 1 FROM CONNECTICUT VALLEY 218 FIGURE 5.9 /3O I f, SYM. Type of Tejt (9o 0 0 CKUoC 1.20 0 1/0 El CKo C I-, CIUE 0 c(-[E 0o sO sO sO /00 /1b 90 80 /f C/~/I/ ond C/iL - 70 / I Wf 60o r - . . m- . 0 40 - 1 J01 Ik 1 3 OCR ?I Eu vc AT "i~c, C= 0.2% CIUE, I 4 I s I 6 I I 7 8 VERSUS OCR FROM CIUC, AND CKoUE TESTS ON SAMPLES FROM EAST WINDSOR 2 19 FIGURE 5.10 I---- -~ 0.2z 3 0 S5T ~~~~~~~~~~~~~7~ \ ~~~~~NO. -0.4 vc m 4.0 /.67 CKc/VE3.6 50 CIR7 *_ EKE-i C 7.TSM. K9 l,,' o -0.2 _~~~~~~~~~~~~~~~~~ ~,.,.=.. . -0.6 TYPE OF sYM I I 2 -CI) I I I 4 I I 6 . -- . I 8 AXIAL STRAIN, /4 /0 a % .; 3.0 2$ zo - * CK UE A O. - 0 _. I a. I I 4 I i 6 I J I 8 AXIAL STRAIN, (a i /0 i I 12, I % CURVES FROM CIUE NORMALIZED STRESS-STRAIN AND CKoUE TESTS ON NORMALLY CONSOLIDATED EAST WINDSOR VARVED CLAY FIGURE 5.11 220 /. f. 0. -o Ir.O.; Li AXIAL STRAINV, 6a % ¥1 h &V AXIAL STRAIN, Ea % NORMALIZED STRESS-STRAIN CURVE' i CKoUE TESTS ON OVERCONSOLIDATED CONNECTICUT VALLEY VARVED CL 221 FROM CIUI E (OCR = 4.0) WYS FIGURE 5.12 scLIU SYtlBOL TYPE OF TEST OCR 3000 0 CIK LE Eu-= Secant Modulus 1. IO 2000 - O U C/LIE CKo0E 2.0 C/lUE 2.0 4.0 4.0 Ceo C k, UE E /000 _ (-< Eu Su OCR from CIU tests ts 5$00 400 300 200 _ /00 _ 2 tests (Eoch from Amhert and East Windsor) A^ I 0--C ) 0.2 ·- I 0.4 0.6 I 0.w 10 FROM VERSUS Af FROMCIUE AND CKoUE TESTS ON SAMPLES FROM EAST WINDSOR 222 FIGURE 5.13 One of A c directions acts perpendicu Jar to the varves - Cl/, (9 = 90) a I tJN cr a (a c, ,T=O -0o) ERTICAL LOADIN& (0=0) (0) One of tAc directions j acts perpendiclar to the vorvcs A aa0 7 Cl CIUc )E A o0, =a S2 > a3 {e =o) (b) (4J (e -90) = 0) > a( C = o )= o (&C25. = aSr.Y) O HORIZONTAL LOADIG& (3=90) STATES OF STRESS FOR CIUC (=O0), CIUE (=O0), CIUE (- 90), AND CIUC( :90) TEST SAMPLES 223 FIGURE 5.14 0.4 0.3 _ 7EE -w ________ C ./------0---- 0.2 I- l //=_ 0.1 0 CIJE e =90)i ---- I 0 I iII Cl-C(eA= :0); i 2 6 4 I Test Ala. E/E-3-! TestNo. EIC-I-I I 0 I /0 I 2 4 .3 A .__ - -- 2 I I O I II I 4 ,I I 6 8 I /0 /2 NORMALIZED STRESS-STRAIN CURVES FOR NORMALLY CONSOLIDATED CIUE (= 90) AND CIUC (6- O) TEST SAMPLES (VERTICAL 224 LOADING) FIGURE 5.15(a) 0.8 T1 _ _ ____ ___ I - 0.6 v- 0.4 CUE (e =9o): TeJst No. EIE-3-3 --- 0.2 CIUC (e= / 0 l 2 0 4 l l l est No. EIC-1-3 ): l l /2 /0 8 6 £0, % ---- TE 4.0 TC 3.' J.0 _-0- _- /7 Ir. 2S / 2.0 OC _ /// /.5 ,. _ ltl I I I I 4 I I I 6 I I I /0 I /2 NORMALIZED STRESS-STRAIN CURVES FOR OVERCONSOLIDATED CIUE (8= 90) AND CIUC (8= O) TEST SAMPLES (OCR = 4.0) 225 FIGURE 5.15 (b) 0.4 0.3 _ TC i TE a2 z . VC F/ic e 90); Test No: EC-3-I -- 0/ ---- e-) O n I 4To I 2 CI u1 t (e- o I I I 4 6 I Test No: EIE-I-/ I 8 /0 12 £q, % I lz h o % Ea, % NORMALIZED STRESS-STRAIN CURVES FOR NORMALLY CONSOL_IDATED CIUE (e=O) AND CIUC (e = 90) TEST SAMPLES (HORIZONTAL LOADING) FIGURE 5.16 (a) 226 "cri £q, % 4.0I I .0TE '0-- 3.0 Rz cr " 2.0 PA lId L. p I I I I 4 6 8 I I I /0 /2 So, % NORMALIZED SIrRESS-STRAIN CURVES FOR OVERCONSOLI DATED CIUE (8=;) AND CIUC (8= 90) TEST SAMPLES (OCR = 4.0) 227 FIGURE 5.16(b) W -J p- Z O o 0 w D Z O Z 0 L 0 W W Oa- w Z n-Q fW WO w m > ZoU W O N W r on? Z Pp- w 1l 228 FIGURE 5.17 z O O3 -Jon II 1a < -Jl IU D LI-O LL T a- C) N O_ z Io-- ul )3" Q 0 229 FIGURE 5.18 0 Cf, Dz O- Oh LL w ALC (n 0 nL wz .J < Ib~ rl6ft l zo:: > 0 Cl : Ow WI- Zt z 0N> 0 wn L hlU (3 _o 4s IZ) 6CS~~~~~~ :i !5 z,: 230 FIGURE 5.19 O6 - ! _ - 0.4 av- h - U/SC , CiyYPSC, Test Ala. A'P-I 0.2 _ --- a c) cKO Uc ; I 0o.s 0 - - o. APC- 4 irt. - --- TestNo. i at q 0 ct 9 0 at AKC-I I I I I I I /.s 2 4 6 H /0 I /.5 2 4 6 8 /0 2 I I I I II .2 /4 /2 /4 Ct.1o A F NORMALIZED STRESS-STRAIN CURVES OF NORMALLY CONSOLIDATED SAMPLES FROM CKoUC AND CKoUPSC 231 FIGURE TESTS 5.20 Y lrvg ,0 J.3 ~~~~~~~- I-,~ - 2.5 hi abv 2.0 -_--Cl cdYE; Tt 1.s - No.EKE-I CKo.LPSE; Trt No. NPE-2 -. CKKoPSE; 7t 7No. NPE-I Io vrt . 0 I I 2 I I 4 I I 6 I £a, °/ I 8 I I /0 I I A* I 14 A NORMALIZED STRESS-STRAIN CURVES OF NORMALLY CONSOLIDATED SAMPLES FROM CKoUE AND CKoUPSE TESTS 232 FIGURE 5.21 W -3 J w WZ < Q: w Z Zz -Jo a0 or IJ- ()9 o-z (n w Uf) aJ 0 0 W ?0 WLL LAO IL w cr Ow WI c>o 0 <O Ct I I I I~ I iI: ,:Ihk1 233 FIGURE 5.22 4L TIrc APPLIED COMPARISON OF SHEAR STRESS LEVEL, vc % FROM CKoU PLANE STRAIN, TRIAXIAL, ANI) SPECIAL DSS TESTS 234 FIGURE 5.23 ___ 9-f/er-" I . _ OCR CUi PsC wP CKoVE /Uc CK 028 0.22 0.2S 0.21 0.47 0.41 0.44 0.36' 0.76 0.67 0.72 0.65' 2 I.I _ _ ""N _ ~ ~ ~ ~ ~ TYPE OF TEST SYM e Ck lUE 0 0 0 0 -- cl-E ( =o) C/I/g 990) 0 90 A 0 A 90 C/I/C(( -- ". 9'o) O 90 0.9 oc "I'll\ 11 E 1E * 1 ,, t3, \ .~ ~~- 0.7 Verticai o Horizonto P/ H/ to .s Looding ~ Wjd a3 I I 1 I 2 3 4 I I s 6 7 I I I .9 /0 I /II I I 20 JO 40 _ _ OCR ESTIMATION OF qf avc OF OVERCONSOLIDATED PLANE STRAIN HORIZONTAL AND VERTICAL LOADING SAMPLES FROM CONNECTICUT VALLEY VARVED CLAYS 235 FIGURE 5.24 2E 0 w O- ZO 1_Y) V 0C cn en @0 of_ c Lio Z _ w.OU z I-O Xr z Q0 I I _o o z o w u Q~ n c , V) c] nO O cn W c z 236 FIGURE 5.25 w w m Uf) U) 0 m Ir -i cr: w .0 LiL .x a I-E 16-110 w U w z iI 237 FIGURE 5.26 0.3 NAlo.ESDS-I r I Oonr. zor Bn(L) Tes 0.2 z~~~~~~~~~~~~~ t~> 0./ v-.c I I 4 I I I I I /2. 8 2-, I 16 I I I 20 2 4 20 5.2T 2 % -o./ No.£$D5-2 __,_ 0.6 TESTS CKOUDSS( CKDUDSS(E) ~0.2~FIGURE 4 8 3 16 NORMALIZED STRESS-STRAIN CURVES OF NORMALLY CONSOLIDATED INCLINED SAMPLES FROM CKoUDSS(C) AND CKOUDSS(E) TESTS FIGURE 5.27 238 rr O. 0 -- Wnz O ow F- I LL Iai 0 w z 3 0 L E/za L 0 L 0 w NI1J 239 FIGURE 5.28 z ZJ w: { > C .J w O i< LL a OZQ ,I::{ A N ^ C*U FIGURE 5.29 FIGURE 5.29 a z z 0 oz n Ld LL O U oa EZ C) U O n < [ zo 241 FIGURE 5.30 o 'o w C) lJ U 0 I ri4 o'b I 4bI,$ 00 * ci 3 11 o L w z * vs 242 FIGURE 5.31 0 - - - 0, 5! OCR = 4, Test No: EDS-3 --- _---at o ---.. OCR = 2, Test No: ADS-4 OCR - , Tt No: ADS- I 0.6 P'hn1, rvC o , IX Zh - - 0.4 cb1 - - - -- - _ -- ·- · -? - - · 10 ·-- *-.- / 0.2 .i 00 V I II I I 2 II I I 6 4 I I II 8 II II /o I! I I 14 /Z a, % 0.4 AL4 ~ vc 0 - -0.4 . '~~~~~~~~~c l'~~~~~~~~~~~~~~~ _ _. - I _ _>,~-. _ I_ ., , _r -0.+ l 0.c _---I1. I 0.3 '' r =, l I .I1- 0.2 0.i 0 ... .___....-'. - _--.- ,// _/// I/~ 0 4 I 2 I I 4 I I 6 I I 8 7hZ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I I /0 i I /2 I t~~~~ TYPICAL NORMALIZED STRESS-STRAIN CURVES FROM CKoUDSS TESTS ON NC AND OC CONNECTICUT VALLEY VARVED CLAYS 243 FIGURE 5.32 PS (A OZ E 0 o V v! d bilb C) E 0Z L IE a 0E 0 cr w 0 o E Z v : IO 11 O J I __ 244 FIGURE 5.33 ,< x LL a w a 0C Qa 0C->.'- ~ "ot,b o DWW I. o0 oe- A I .1 u) owFZ0Z 0 FIGURE 5.34 C% bn 0 E L:JW ~ > 0.1 0 o> . O n~ c 0 E vsLJ z q O E C) Cab 0C)~ < £ ,.ilJII 246 FIGURE 5.35 Iw n 0 o0 XL K Co 0r z w w CL (f N ,$ 247 FIGURE 5.36 /.o 2.0 3.0 4.0 So OCR FAILURE CKoUDSS TESTS STRAINS AT hmax AND(v)max ON CONNECTICUT VALLEY FROM VARVED CLAYS 248 FIGURE 5.37 O Q > 0 zZ in 0 UZ n w z t O o -- O n0 0 O Z0 o ,s 0 249 FIGURE 5.38 NN. ~q<% ~ *j ° IIts~~~~~~~~~~~~~L ~ ig \Z fr1 OO 1I-. CNob , e"Fz o~~~v L z ~u - vS v 0c ~rb-c u0 I- c6J O C3 U ` O IJ- uQ) ao) \X , - ' e At- \I II Ie .' ' .! (nc tZ \us oR04 t 51e N o t w 0 ''0 K)(-) 4 3 'q. -! IC~~·~ WOg LL '1 0 to.~'~~~ z: uJ u W u W j)11~ ~LL ,., It I a Z I 0 I >oC 2s50 FIGURE 5.39 6. 6.1 CONSIDERATION OF SAMPLE DISTURBANCE INTRODUCTION AND BACKGROUND 6.1.1 Purpose Sample disturbance in homogeneous clays has been studied fairly extensively (e.g., Ladd and Lambe, 1963; Davis and Poulos, 1967; Bozozuk, 1970; and Milovic, 1970), but disturbance in varved clay has received little attention. The special problems with varved clays include formation of transverse cracks located at the interface between clay and silt portions due to sampling technique (Kenney and Chan, 1972) and separation of varves during trimming of samples (Saxena et al., 1974). In this chapter, methods for minimizing disturbance in varved clay are studied for the purpose of providing: parison of NSP (qf/vm, Af, Eu/ vc, testing methods: (1) com- 4 and c/avm) from these the UUC test, the RECOMPRESSION method, and the SHANSEP method; and (2) recommended methods for measuring the in situ strength-deformation properties of varved clay. 6.1.2 Types and Causes of Sample Disturbance There are two basic types of sample disturbance in varved clay, namely: 1. Disturbance due to the removal of the in situ stresses which caused a change from anisotropic stresses to an equivalent isotropic stress, aps; and 2. Disturbance due to sampling, handling, trimming, and setting up a test, all of which may cause 251 permanent damage to the soil structure, and with varved clays, cause separations or transverse cracks located at the interfaces between silt and clay layers. The separations are most likely to occur between the varves. The formation of cracks or separations are the result of sampling techniques (Kenney and Chan, 1972), and trimming, especially with inclined and horizontal samples (Saxena et al., 1974). Kenney and Chan (1972) concluded that the formation of transverse cracks due to sampling of varved clay samples was primarily the result of the large friction force created between the coarser-grained soil (silt portion) and the sampling tube. The formations of cracks or separations resulting from trimming samples are difficult to avoid, even when a thin wire is used. Such an effect will be very pronounced in horizontal samples, slightly less pronounced in inclined samples, and will be negligible in vertical samples. 6.1.3 General Effect of Sample Disturbance During sampling, the change in effective stress due to the removal of the in situ stress is unavoidable. Even for the "perfect sample," defined as a sample which undergoes only an undrained release of the in situ stresses to end up with an isotropic effective stress equal to aps (Ladd and Lambe, 1963), the strength and undrained modulus of the soil are affected. As a result of structural damage (including both soil structure damage and separation of varves), and expansion (swelling) of 252 the sample, during sampling, extruding, trimming, and setting up of a test, the isotropic effective stress in a disturbed sample is decreased from aps to as (the effective stress of the sample prior to a test). Such a reduction in effective stress in turn causes an additional decrease in undrained shear strength (qf) and Young's modulus (E). In addition, planes of weakness at the interfaces between clay and silt portions, which are created by the transverse cracks or separations (i.e., part of structural damage) may cause further decreases in undrained shear strength and modulus, especially when lf acts parallel to the varves and when shearing is parallel to the varves. This would produce a directional dependence of sample disturbance. 6.1.4 Methods for Minimizing Sample Disturbance Methods for minimizing sample disturbance to be studied are the UUC test, the RECOMPRESSION method, and the SHANSEP method. Since the cracks or separations can be closed by pres- sure, the UUC test (where a cell pressure is used to confine the sample) is considered as a method for minimizing sample disturbance compared to an unconfined compression test. In the RECOMPRESSION method, the sample is Kx consolidated to the in situ vertical and horizontal stresses (Bjerrum, 1973). It therefore minimizes disturbance by reapplying the field effective stresses, i.e., vc = vo and ahc =ho Because of the resultant decrease in moisture content and any prior structural damage (soil structure damage and formations of cracks or 253 separations located at the interfaces between clay and silt portions), the RECOMPRESSION method may yield a sample having a different soil structure and hence different soil proper- ties compared to the in situ soil. Research reported by Ladd and Foott (1974) and Ladd et al. (1977) suggest that, if a soil exhibits normalized behavior when av > am , K consolidated SHANSEP samples (especially NC samples) should yield reasonable qf/avc values compared to those of the in situ soil. The basis of the SHANSEP method proposed by Ladd and Foott (1974) as a means for minimizing sample disturbance effects on strength-deformation properties measured in the laboratory is as follows. As indicated in Fig. 6.1(a), the laboratory curve typically approaches the in situ virgin = v(L) > (1.5-2) avm) vm vm vc Thus, CK U test samples consolidated to Point D should have a compression curve at Point C ( soil structure similar to the in situ normally consolidated clay and hence yield reasonable qf/avc values if a soil exhibits normalized behavior. For overconsolidated samples (A and B in Fig. 6.1(a)), the samples are first consolidated into the virgin compression range to obtain a normally consolidated clay (i.e., at Point D), and unloaded prior to shear (shown as Point A and B in Fig. 6.1(a)). These OC samples then should yield reasonable qf/avc values at the required OCR's. It is seen in Fig. 6.1(a) that the SHANSEP and RECOMPRESSION samples at the same OCR have different magnitudes of compare vc of Sample A and A' in Fig. 6.1(a). 254 vc' e.g., Therefore, the comparison of the measured soil parameters of these samples must be in normalized form. For the purpose of making exten- sive comparison of NSP from SHANSEP and RECOMPRESSION methods of consolidation, RECOMPRESSION samples considered in this study will also include those which are consolidated above but below .vm NSP (qf/avm Aft Eu/avc, and C/vm) vo of a RECOMPRESSION sample such as that indicated by B' (Fig. 6.1(a)) will therefore be compared with those of a SHANSEP sample which has the same OCR. qf/Cvm versus Figure 6.1(b) shows a hypothetical plot of vc/vm(L) from SHANSEP samples A, B, C, and D. Since samples C and D are normally consolidated, their qf/vm are identical if the normalized behavior concept applies. Figure 6.1(c) shows hypothetical plots of qf/cvm versus avc/avm from RECOMPRESSION and UUC test samples and qf/%vm(L) versus avca vm(L) from SHANSEP samples. Because of the difference in the capabilities for minimizing disturbance effects and the use of different methods of consolidation, qf/vm of the RE- COMPRESSION sample at the in situ OCR can be higher or lower than that of the SHANSEP sample. preshear effective stress as As a result of the smaller qf/avm of the UUC test sample will be lower than those from the SHANSEP and RECOMPRESSION samples at the in situ OCR. This chapter compares data obtained from the SHANSEP and RECOMPRESSION methods in an attempt to ascertain their relative advantages and disadvantages. Results from both isotropic and K O consolidated tests are included since CIUC tests on samples cut at different inclinations have been used in practice. 255 6.1.5 Experimental Program Table 6.1 presents the experimental program used in the study. Since sample disturbance can affect the undrained shear strength behavior differently for various loading directions, the investigation is made for three loading directions: cal, inclined (450), and horizontal. and E/ NSP (qf/avm' Af, verti, C/avm vc) of K o consolidated OC SHANSEP samples, RECOMPRESSION OC samples (Ko and isotropically consolidated), and UUC test samples are compared. High quality block samples (in situ OCR ~ 4) from East Windsor were primarily used for the UUC and RECOMPRESSION test programs, supplemented by some data from 5 in. diameter tube samples from Amherst and Northampton. Re- sults from SHANSEP samples (presented in Chapters 4 and 5) are used for comparisons shown in Table 6.1. It should be noted that K o consolidated RECOMPRESSION East Windsor samples at an OCR of four have K o equal to unity. For simplicity, these samples were, therefore, isotropically consolidated in the laboratory prior to shear. Data on overconsolidated samples with 8 = 0, 450 and 900 are used to study the method of consolidation in CIUC tests. 6.2 EFFECT OF METHODS FOR MINIMIZING DISTURBANCE ON UNDRAINED STRENGTH BEHAVIOR It is emphasized that the soil samples used in the study, especially those from block samples, are of much better quality than normally encountered in practice. 256 Thus, results of this study may not apply to the poorer quality "undisturbed" samples obtained from 3 in. diameter tube samples or obtained from 5 in. diameter tube samples with poor sampling techniques. 6.2.1 Behavior from Vertical Loading The upper half of Table 6.2 summarizes test data from CKoUC tests on SHANSEP and RECOMPRESSION samples. Figures 6.2 through 6.5 present plots of test data from the UUC test, and from the CU tests at OCR's of two and four. These data show the following results. 1. At OCR's of two and four, CKoUC tests on SHANSEP and RECOMPRESSION samples at the same OCR yield essentially the same qf/Ovc within experimental accuracy. However, RECOMPRESSION samples have a higher NESE at qf, and a higher pore pressure parameter A than the SHANSEP samples (Figs. 6.2 to 6.5). Therefore, the behavior in terms of effec- tive stress is really quite different. Further- more, the stress-strain behavior is also somewhat different (Figs. 6.2 and 6.3). samples have a lower RECOMPRESSION f and higher EU/vc high strain, though E/vc at at low strain of both SHANSEP and RECOMPRESSION samples are nearly identical. Based on a comparison of - E -u behavior, it is seen that RECOMPRESSION samples exhibit a more sensitive and brittle behavior. The fact that RECOMPRESSION samples have larger normalized 257 pore pressures, and also a higher NESE at qf explains why qf/%vc from SHANSEP and RECOMPRESSION samples turned out to be practically identical. 2. qf/avm from the UUC (0=0) test is also essentially the same as that from CKoUC tests on SHANSEP and RECOMPRESSION samples at OCR of four, though the UUC test sample has the largest Eu/avm. f and the smallest The agreement in qf values indicates that disturbance due to structural damage and removal of in situ stress is relatively small, though the modulus is significantly reduced. (Note, however, that disturbance due to separation of varves, if there is any, shown from TC tests will be small since shearing would tend to close the separations or cracks). However, as will be shown in Section 6.2.2, thedisturbance of this block sample is mainly due to separation of varves. This has a pronounced effect with horizontal and inclined samples, but little effect on vertical samples. It is emphasized that the good agreement among UUC and the SHANSEP and RECOMPRESSION CKoUC test qf/avm values is based on data obtained with very good quality block samples from East Windsor. With 5 in. diameter tube samples (such as those from Amherst and Northampton), where the effect of disturbance is greater, especially from samples at great depths, qf(V)/avc from UUC tests are generally much lower than those from SHANSEP samples, Fig. 6.6. These data also show that, because of 258 variable sample disturbance, UUC qf values from tube samples are very scattered. qf(V)/avc from a RECOMPRESSION CK UC test on 5 in. diameter Amherst tube sample is compared with the values from SHANSEP and RECOMPRESSION block samples in Fig. 6.7. These data show that qf(V)/Fvc of an Amherst sample with OCR of 1.6 is only slightly higher than that of the SHANSEP samples. noted that qf(V)/vc from a CIUC (=0) It should be test on a RECOMPRESSION sample (OCR=1.7) from East Windsor (Long, 1975) is approximately equal to that of the Ko consolidated RECOMPRESSION samples. 0 These data indicate an insignificant effect on stress system during consolidation on qf(V)/Zvc obtained from the RECOMPRESSION method. (The same trend is also observed with SHANSEP samples; see Chapter 5.) At an OCR of four, it is also interesting to compare data from CIUC tests on SHANSEP and RECOMPRESSION samples. (Note that at OCR=4, the "CKoU" RECOMPRESSION sample was isotropically consolidated.) qf/avc and NESE at (a1/a 3) from these tests max are roughly the same (see bottom part of Table 6.3), though Af and NESE at qf of the RECOMPRESSION sample are higher. In conclusion, for vertical loading, the SHANSEP method of consolidation yields reasonable values of qf and NESE at (al/O3)ma , even though the magnitude of a is significantly larger (3.6 versus 2.4 kg/cm 2) than the in situ value. However, it yields a lower Eu/avc and quite different behavior in terms of effective stress compared to the RECOMPRESSION method. 259 6.2.2 Behavior from Horizontal Loading Test data in Figs. 6.4, 6.5 and 6.8 to 6.11 and the sum- mary in Table 6.2 show the following results. (1) At OCR's of two and four, the RECOMPRESSION CKoUE test samples have a lower qf/avc and f, and a higher Af and Eu/avc than SHANSEP samples at the same OCR (Figs. 6.8 and 6.9), though the NESE at qf (also same envelope as at (/a these samples are identical. 3 ) of max Therefore, the decrease in qf/avc from SHANSEP to RECOMPRESSION results from larger normalized pore pressures in the RECOMPRESSION samples. of The lower values f, and the higher values of Eu/avc, (Fig. 6.10), Af and Au/a from RECOMPRESSION samples show that RECOMPRESSION samples exhibit a more brittle and sensitive behavior and thus have a more sensitive soil structure. These results and results in Section 6.2.1, therefore, lead to the conclusion that the SHANSEP method of consolidation causes the soil to have a less sensitive and less brittle structure than the in situ soil since the high quality undisturbed RECOMPRESSION block sample should have a soil structure close to that of the in situ soil. (2) At the in situ OCR (OCR=4), qf(H)/avm from the UUC (6=90) test is about 80% of the RECOMPRESSION CIUC (=90) and 62% of the SHANSEP CKoUE value (Fig. 6.8). value The lower UUC qf and the large decrease in strength after failure is thought to be mainly caused by disturbance due to varve separation, even though the sample developed a failure plane across the varves. However, it is not known whether the separation occurred during sampling or mostly as the result of trimming. 260 (Note that the effect on vertical samples would be much smaller since shearing would tend to close the cracks.) (3) Further evidence that disturbance (presumably due to varve separation)is most important with =90 sample is partly provided (since.CIUC.SHANSEP and RECOMPRESSION samples have dif.ferentsoil structure) by comparing CIUC (=90) RECOMPRESSION and SHANSEP samples. test data on The strength of the RECOM- PRESSION sample is only about two-thirds of that from the SHANSEP sample at OCR's of 2 and 4 (Table 6.3). The moduli from RECOMPRESSION tests are also lower (Figs. 6.11 to 6.13). This is in contrast to the CKoUE test where the RECOMPRESSION strengths were 21% less at OCR = 4 and 6% less at OCR = 2. (Note, however, that the CKoU RECOMPRESSION samples had a much higher undrained modulus and larger pore pressure, i.e., they behave in more sensitive and brittle fashion). This suggests that the RECOMPRES- SION method of consolidation only partially minimizes the ef- fect of varve separation with horizontal samples. The fact that the strength in a CIUC (=90) test is lower than that in a CKOUE (0=0) test, both performed on RECOMPRESSION samples at OCR= 4, despite the larger magnitude of a2 applied in the extension test also suggests that disturbance (presumably due to varve separation) is most important with 0=90 samples. In summary, the two most important findings appear to be: 1. Disturbance due to varve separation is most important with horizontally trimmed samples and can be only partially overcome by the RECOMPRESSION method. 2. The SHANSEP method causes the soil to have less 261 sensitive and brittle behavior. Finally, varve separation may have affected the RECOMPRESSION CKoUE test at the in situ OCR of four, perhaps causing a lowering of the strength, since the difference in the RECOMPRESSION and SHANSEP strengths at the OCR is much greater than an OCR of 2. 6.2.3 Behavior from Inclined Loading Test data from the CIUC (=45) and UUC (= 45 ) tests on overconsolidated samples (OCR=4) from East Windsor, presented in Fig. 6.14 and Table 6.3 (lower part), show the following results. qf/avm from the UUC (=45) test is only 64% of that from the SHANSEP CIUC (0=45) test and 75% of that from the RECOMPRESSION CIUC (=45) test. The decrease in qf/vc from SHANSEP to RECOMPRESSION samples is due to larger normalized pore pressures while the NESE at (al/a3)max of these samples is probably identical (Fig. 6.15). The fact that UUC tests and the RECOMPRES- SION CIUC (8=45) test samples failed along a plane of weakness (located at the interface between the clay and silt portions), while the SHANSEP sample failed within the clay layer partly explains their lower qf/vm. However, because of the use of a high isotropic consolidation stress,the SHANSEP strength is probably too high compared to the in situ soil. Comparison of test data (Figs. 6.16 and 6.17) from SHANSEP CKoUDSS tests and from one RECOMPRESSION sample also indicates a trend similar to that from CIUC (=45) RECOMPRESSION (vc Vc = tests: h/avc of the ) vo Vo Amherst sample is lower than that of the SHANSEP sample (Fig. 6.16). 262 The value of G/i at Y = 1% from RECOMPRESSION test is also somewhat lower (Fig. 6.17). 6.3 DISCUSSION Disturbance in Varved Clay As stated in Section 6.1.1, disturbance in varved clay is due to the removal of the in situ stresses, soil structure damage, and varve separation. For block samples, unless alf acts perpendicular to the varves, disturbance due to varve separation, which probably occurs mostly during trimming, is an important factor. As shown from UUC tests, it is most pronounced in inclined and horizontal samples, but perhaps small in vertical samples. dependent. Thus, disturbance in varved clay is directional The following experimental evidence illustrates the existence of disturbance due to varve separations in block samples. (1) As shown in Fig. 6.18, for an OCR = 4, the increase in qf from a UUC ( = 45) test to a RECOMPRESSION CIUC (= 45) test is about the same as that from a UUC (0= 90) test to a RECOMPRESSION CIUC ( = 90) test, while qf(V) from a UUC (=0) test is essentially identical to that from a RECOMPRESSION CKoUC (=0) test at OCR = 4. (2) The qf in a CIUC ( = 90) test is lower than that in a CKoUE (6=0) test, both performed on RECOMPRESSION samples at OCR = 4, despite the larger magnitude of a 2 applied in the extension test. (See Section 6.2.2.) (3) The fact that a failure plane developed at the interface between varves in the UUC (0=45) test instead of within the 263 clay layer as observed from SHANSEP samples indicates the existence of a plane of weakness at this location (Section 6.2.3). With 5 in. diameter tube samples, the effect of disturbance is greater (see test data from Amherst and Northampton, Section 6.2.1) than for block samples, probably because of increased soil structure damage. With tube samples, qf(V) from UUC (= 0) tests are generally much lower than would be obtained from RECOMPRESSION CKoUC tests. Thus, based on datafrm vertical load- ing, one expects that disturbance in tube samples will cause greater reductions in qf in all directions, compared to block samples. SHANSEP Versus RECOMPRESSION as a Method for Minimizing Sample Disturbance The increase in qf from UUC tests to RECOMPRESSION (vc =OO) CIUC tests on inclined and horizontal samples indicates that disturbance due to varve separations can be minimized by reconsolidating the samples. SHANSEP method of consolidation appears to be more effective than the RECOMPRESSION method in minimizing this type of disturbance, especially with inclined and horizontal samples, based on the following data from CIUC (0=45) tests on block samples. Despite reconsolidation to avo, the failure plane which developed in the RECOMPRESSION CIUC (=45) test occurred at the interface between silt and clay portions, whereas it occurred within a clay layer for the SHANSEP sample. In addition, the difference in qf(H)/avc between the RECOMPRESSION and SHANSEP CKoUE (6=0) tests increases with increasing OCR, i.e., 0.375/0.355 = 1.06 at OCR = 2, and 0.64'5/0.535=1.21 264 at OCR = 4 (see Table 6.2). Since both SHANSEP samples had been consolidated beyond the in situ avm, this suggests, but does not prove, that SHANSEP may minimize disturbance due to varve separation better than the RECOMPRESSION method. However, it is not certain if the 20% difference in strength at OCR= 4 is mainly due to the influence of the varve separations. Though the SHANSEP method of consolidation can effectively minimize disturbance due to separation of varves, it also has a drawback in that it causes significant changes in soil structure, especially when isotropic consolidation is used. effect of these changes below. . in The the soil structure is discussed - With CKOU tests, except for possible effects of varve separations (when alf does not act perpendicular to the varves), it is thought that OC RECOMPRESSION data on block samples give the best indication of the in situ behavior of varved clay, since the structure in the RECOMPRESSION sample should be close to that of the in situ soil. For both vertical and horizontal loading, OC RECOMPRESSION samples compared to OC SHANSEP samples generally have significantly higher moduli, pore pressures and NESE at qf (when it is not equal to that at (ol/a3)max in the vertical loading). e.g., These general trends show that OC RECOMPRESSION samples act in a more brittle and sensitive manner. This in turn strongly suggests that the SHANSEP method of consolidation causes the test samples to have a less brittle and sensitive behavior than that of the in situ soil. 265 Thus, though data (mostly from NC soil) over a small MPPR range on Connecticut Valley varved clays show normalized behavior with'respect to qf, Af, and c/avm when consolidated above avm' based on OC East Windsor block sample test data one concludes that stressstrain-pore pressure parameters from OC ( 2 < OCR < 4) SHANSEP samples do not represent the true in situ soil behavior. How- ever, SHANSEP samples apparently yield reasonable estimates of qf and NESE at ( 1 /a 3 ) max for both vertical and horizontal loading. With CIU tests, SHANSEP yields much larger qf values than the RECOMPRESSION method, except for vertical loading on 8 = 0 samples, as shown in Fig. 6.18. This may result both from the influence of disturbance due to varve separation which is important with inclined and horizontal samples, and from the fact that high isotropic consolidation may produce a less parallel orientation of clay particles perpendicular to the in situ vertical direction. 6.4 SUMMARY AND CONCLUSIONS Block sample test data presented in this chapter show that the UUC test is not suitable for measuring anisotropic strength and modulus. separation Despite using block samples, disturbance due to of varves causes the value of qf from inclined and horizontal samples to be too low compared to more reliable data obtained from CIUC RECOMPRESSION tests. For typical tube samples, increased soil structure damage will probably cause a further reduction in qf and undrained modulus in all directions. 266 OC CKoUC block sample test data show that the SHANSEP method of consolidation causes a change in soil structure to produce samples that are less brittle and sensitive than the in situ clay. On the other hand, the RECOMPRESSION method bet- ter preserves the in situ structure. However, SHANSEP may yield more reasonable estimates of qf in cases where disturbance due to separation, of varves affects the results. With CKoU tube samples, which are likely to be much more disturbed than block samples, little data exist for comparison of the SHANSEP and RECOMPRESSION methods of consolidation. But in the view of the author, SHANSEP method is probably the better approach if the in situ soil has a low OCR, since RECOMPRESSION yields the maximum discrepancy between the in situ and laboratory compression curves in the vicinity of the maximum past pressure (e.g., see Fig. 6.1(a)), while use-of the RECOMPRESSION method in tube sample is probably better if the clay is heavily overconsolidated and there is little disturbance due to separation of varve. In any case, SHANSEP has the advantage of mini- mizing adverse effects of varve separation whereas RECOMPRESSION has the advantage of better preserving the in situ structure of OC samples. For both block and tube samples, CIUC tests on samples with different inclinations consolidated by either the SHANSEP or RECOMPRESSION methods are not recommended for obtaining anisotropic undrained parameters. In general, the pros and cons of the SHANSEP and RECOMPRESSION methods of testing for use with good quality "undisturbed" 267 Connecticut varved clay samples are as follows: (A) RECOMPRESSION Method Advantages (1) OC RECOMPRESSION samples (OCR > 2) probably yield reasonable estimates of in situ Su/avc, though we can not really be sure whether it is too high or too low and the error probably depends upon the sample quality and direction of loading. (2) RECOMPRESSION samples probably better represent the in situ pre-failure a-e-u behavior of OC samples, especially for modes of failure involving rotation of principal stresses. Disadvantages (1) If soil parameters are not related to stress his- tory, i.e., OCR, each new job will need CKoU testing to obtain data versus depth. (2) For NC and perhaps slightly OC deposits (OCR < 2) the RECOMPRESSION method of consolidation (avc vc overestimate the in situ qf. = a) vo could (B) 'SHANSEP Method Advantages: (1) For normally consolidated and slightly OC deposits, where good quality undisturbed samples are especially difficult to obtain, the SHANSEP method probably yields better estimates of the in situ qf and -e-u behavior. (2) NSP from many types of SHANSEP strength tests have been shown to be the same for several locations within the Connecticut Valley (see Chapter 4). (3)' Thus, since soil parameters have been developed 268 as a function of OCR, the testing program can concentrate on consolidation tests for determining the stress history, plots of NSP versus OCR already having been established. (4) NSP versus OCR data provide information to predict changes in in situ soil parameters due to changes in consolidation stress, such as occur during consolidation under embankments. Disadvantages (1) Because of changes in soil structure, the SHANSEP method of consolidation may not provide very reliable a-e-u data for OC samples. (2) Because NSP are expressed as a function of OCR, the SHANSEP method is not suitable to use at a site where the stress history is very scattered. In such cases, tests such as the field vane are recommended. In summary, the RECOMPRESSION method is recommended if the deposit is heavily overconsolidated (OCR) 4) and good quality samples can be obtained, though it would still be desirable to correlate the results with values of in situ OCR and with those from SHANSEP method. In such cases, when predictions of de- formations and pore pressures are especially important, the RECOMPRESSION procedure will probably yield much better parameters. For cases where stability is of prime'concern, and if the stress history can be established with reasonable certainty, then the SHANSEP method has a distinct advantage since extensive Su/avo versus OCR data exist for the Connecticut Valley varved 269 clay. Finally, for normally consolidated and slightly OC deposits, use of the SHANSEP method is recommended. 270 __ __ ___ u'l - r 0 c n n /n IV A oV. o o 0OV0 0 0 00H 4. z E 0 H o 0I0U- N H; H 0 N a oo oL oNo V N N 10 i,, ln m 4EPa:: 00 q D M r o 10 % 0. ' N IVN N % , 0 i4 H N ~ oU N m. 0 ri r 0 a iz N rH, N qi o o o o _ I 00 o t bO oa coU aH o o o _ 1.40 H 0 ad*rIEU U *4 0i '0 a) Dvc __ NH ) O _ W _ IH 0 Dg 0 P: Ut 0. 11 0 . , M )O a)O | 0_ _ .,4 U. _ ci~ 0 004. b4 ~ot . -I 0H0 H Ei- t: 0 II $4II . . . 0 0 o o E4 zI M H _ __0_ P a4 0 rid No a HO ', 4 0 O O r4 $4 0 . , > M .'4 o0 $4 $I 0 N 0 o 0 M I I III 271 a) II C! tg II . 0 .5 i w 0 : . .1.H 0o 0 > $4 O *rj s .54 H 4 I 0o . 0 zcdc- > M) x u [ Table 6.1 1r o q HO H Oi 0 Itb o o o o o o o0 X lV 0 - ·- r,. U) 3 co n 0 C5a 5a r. 0 0n* a 0a r- r . .H 0 m H 0a 0 r r U) II l-I 0 N l ( 1_ 4-) ( t" o . O N 1 i -A o H E.6 V~b C Q-Is-.. b ltl Eu c_-I ' a .e o .0_oo . IH OOD N* a COi U 4j __m N 0 rH _ a a O I O . 0 cqo r,. rJ ff r n W * r-4 *ql f i. rdA· A G N, ,- zI"... I bC *, HIAIAOIAIAOU')6~~~~~ I ' 0: 4 -s----O -r o Iff,.. - U ooYa X1. . 0 O a ooo _ 0ae o0 o0 OO_ I I 4.) FW. W n 0 H H LA a c . 00 rlGO E r'. O CQ_ n * U) En rn H 0 0 44 . .'.·N·. Ur uz 9 i^ H O Ln _) 0 T^0. I1~H urH < H rI 0. 'O u0 H. EW 1 1 O) 07 <H ..4 II U) .. . X. C C0 I-I= Table 6.2 272 III dP N oN II H 0 0N o00 o H m LA CN N N CO, H O N o- H o oco N -. o -N o o o o N Ln N N 4. o) 0 O Ori co O 0 o t:oXoW 4 o 01r A M 0' * e0 U) P04 O u'l * o 0 0o o 00 S o*n 0. (v,) o o o O N Ln N) N. o . o I .' - I o 44 44 1U WdP .a u 1 En Ir 0 0 00 O o On oH UN OI r o 0 U) M * 'U :o 0 - I LA H CN _I N o O NH H:n o o O H. O N 0 O LA , o N LA N N 0 * O H 00 O 0 ' O' O 0 S ro U) 0 l- 0H U) MU U) q0I U1 H U o 0 IP 0 0) M: N 18 13 u I II rM n E Po N 40 tc Ei i N I M UZ O r-4 I en' M I I EQ) H w I ti: w n I I ) I I N I ') I U I H A U H . U U H H W -. - l 273 i ,-I I i ,-i I L) rH U H W H r C) 4.) 0 Table 6.3 5'JJ In Mrve c7ryc 0vc - In 1% °-vm (L) ot A- aC -4 I), Somp/es of A /9 /0 9 Fron 6r. () C nd A' have the same OCR '(fao) O No 6:y" 10 SHANSEP Method D BC A /c/ O (b) ) bc/ /-/r Al or qf/ from i/ SHJANSEP A )Raneof S/. m () rom RECOMPRESS10N method Ul test /. cr,,, /,7 51tv or Cr.. v 1 (c) rvon , a) GENERAL EFFECTS OF DISTURBANCE ON UUC TEST, RECOMPRESSION, AND SHANSEP SAMPLES 274 FIGURE 6.1 - -- 0.35 --. C--,' 0.30 m 0.2 // 0.20 RECOMPRESS/ON ({rvo) Test Alo. ERIC-/) -- SHANSEP (/est No. EKC-5) .UUL/, (Test No. EUC-/) .- * / / IN I/ 61" 0./0 OCR 0aos I I 2 co I ]~ I I , 6 4- I I I I ... /0 8 AXIAL STRAIN, eo I I I % 6.u r so h 40 &v 3.0 / 2.0 i 4 2 .-- ¢_ 2 6 8 /0 /2 /4 AXIAL STRA IN, 64 % r= r 0.7 A r 0.5 0.3 - nI L- I I _ _ I , i I I 6 8 /o / /4 AXIAL STRAIN, a % EFFECT OF METHOD OF CONSOLIDATION ON VERTICAL UNBEHAVIOR FROM TRIAXIAL COMPRESDRAINED -g-STRENGTH SION TESTS ON EAST WINDSOR VARVED CLAY OCR = 4 FIGURE 6.2 275 0 .2. 4- /2 /.o _ 0.6 PAAAP.'J('AI /rF r\_yc 1-111, b IN 0.4 It = vyC -- 4' -, .- v/m7 (Test No. ERKC-/) SHANSEP (Test No. AKC-2) --0.2 0 I I I 2 0 I I 4 I I I I /0 8 6 AXIAL STRAIN, I I /2 I .,.I ,% AXIAL STRAIN, a, % 0.7 A I- 0.6 s -r~~~~~~~- 0.5 \ \I 0 // n 2 Er I I I I I I 4 6 I I I 8 AXIAL STRAIN, I 17 I I I I I /2 /0 i I /4. (0,%/ EFFECT OF METHOD OF CONSOLIDATION ON VERTICAL BEHAVIOR FROM TRIAXIAL COMUNDRAINED o--STRENGTH PRESSION TESTS ON EAST WINDSOR VARVED CLAY AT OCR=2 276 FIGURE 6.3 ILJ^ a. C) zz 0 OT LLcrn -Jo C- IW C>1 L ' Z LLW > w 0oz IE I CLL F z kf IN 277 FIGURE 6.4 a >- z I I I) I- 0 Oo o 00W O LL I o .JO .I -r 2 e o a M O0 o Z < 6 - 278 _ I FIGURE 6.5 cr-·rr C /3 a*~~~~~~~ U (*~~~~~~~~~~~~~~~~ I 1 TYPE O LOCA TiONA ast TEST CKAN 065 Windsor SYM. P) 0 (SH4NVSEP) £ost Windsor C,oVC (RECOM) Amrnherst UU(V) North - amp ton Ut v) W/indsor A ± UL(v) - East 0.S 0 - qf (v) ofvc Data from or V~O Amherst A/ A 0.35 _0_ S = qf · _, 0., z( U _ - / I ' I. 0 a .=I I 2.0 OCR. 4.0 I S0 I I 6.0 70 8.0 OCR qf(V) COMPARISON OF FROM Vc CKoUC TEST SHANSEP SAMPLES AND UU TEST SAMPLES FROM AMHERST AND NORTHAMPTON 279 FIGURE 6.6 0.7 0.6 C Test 0 UA-CK tesults from Long, /97S 9q(V) 'vc K solidated SHANSEP s E/ ornpIes From F 9 0.4 . 4., /4 Notes: () R= PE(COMPRES510N S SH -2) E =Ea.rst Windsor 0.3 Ar n herst A I ,A r- -- A _ TEST A CKOUC 0 0 l 0 I l E E -7-Uc v7T7c E . . 3 2 4- TYPE OF SAMPLE t---------- E 0 . MOC . 0 0 - SOIL LOCATION TYPE OF !._ . __ = e SYM. 0.2 4 NSEP . R R Block R Bloc S Block I 5 'Bloq/;: 6 7 8 OCR COMPARISON qf (V) OF =VERSUS CIUC, AND UU(v) TESTS SAMPLES OCR FROM CKoUC, ON SHANSEP AND RECOMPRESSION OF AMHERST AND EAST WINDSOR VARVED CLAYS 280 FIGURE 6.7 C-( (T 7 AXIAL STRAIN, E,, % 6.0 ..'ERIC-3-2 7est No. ERIE-/-/ No. Kf-3 --- Test s0 4.0 4 .-2. 0 /O 8 6 AXIAL STRAIN, /2 /4 I 1 E, % /o 0.8 A 06 - 0.+ n.2 -0 -" -, I .. - I 2 ' ' 4 I 6 I I 88 I / I I AXIAL STRAIN, a,% EFFECT OF METHOD OF CONSOLIDATION ON HORIZONTAL UNDRAINED cr-E-STRENGTH BEHAVIOR FROM TRIAXIAL TESTS FIGURE 6.8 OF EAST WINDSOR VARVED CLAY AT OCR = 4 281 ,, (r,y, 5.3 , Test No. ERIC-3-/ o..* Test No. ERKE-I AKE - I Test ANo. 45 0 0S·· 2.. I -S * * * , - ...... -. . -. -r -- . -. _- /._ I I I I 2 I 4 I I I 6 I I I I I I t2 8 O 0.7 A 6* O.. _- j, . I -- _- - . -. .- - .z C 0 I I 2 II II I I 6 8 I I /0 I I I /2 AX/AL STRAIN, £o, %, EFFECT OF METHOD OF CONSOLIDATION BEHAVIOR 0--STRENGTH ON HORIZONTAL UNDRAINED FROM TRIAXIAL TESTS OF CONNECTICUT VARVED CLAYS AT OCR = 2.O FIGURE 6.9 282 /4 Ei/. at 29S 2 / 3 4 S 6 7 OCR Eu I Aq 6vc AT Aqf FROM CKoUC AND CKoUE TESTS ON SHANSEP AND RECOMPRESSION SAMPLES FROM CONNECTICUT VALLEY 283 FIGURE 6.10 0.8 A_ s ; SYM 0.7 - i t - e° 90 90 | SOIL LOCA TION TYPE OF TEST CItc CILC CK0UE TYPE OF SA/MPLE Av0C I E. Windsor S blocK E. Windsor E. Windsor R block R blocK bloc /U (H) 90 E. Windsor No/es: () S- SHANSEP (2) R A'ECOMP'EStY 0.6 From CKEE / SHA NSEP Samples qf rH) 6 vc (IfC. A 4.14) Os 4,0 0. 4 4; --2 T.ets xu,, / .3rests A firor, P .Con,, 0.3 02 V.j I / COMPARISON I 3 OCR 2 q (H) OF vc VERSUS I 4 OCR FROM I I I S 6 7 8 CKoUE, CIUC (8= 90) AND UU (8= 90) TESTS ON SHANSEP AND RECOMPRESSION SAMPLES OF AMHERST AND EAST VARVED CLAYS 284 WINDSOR FIGURE 6.11 a-v OCvtit AXIAL STRAIN, J. ,,% t· , 30 .o.. ' , ._ 00, 2.5 000 2.0 1.5 0 I I =~~~~~~~~~~~~~~~~~ I I ! I I __ L I B 4 6 II I 8 I /0 12 AXIAL STRAIN, 'o,% 0.6 Aw_ ,_ 0.45 A 0.2S e, e _...0 _L_ - 2 _ tw_ - r - 4 -I - - 6 -I I 6 - I /0 I I /a AXIAL SRAIN> , % NORMALIZED STRESS-STRAIN CURVES FROM CI-C ( 90) TESTS ON SHANSEP AND RECOMPRESSION SAMPLES((OCR=4) FROM EAST WINDSOR 285 FIGURE6.12 0.6 0.5 r 0.4 I I [ I I IT I MVO. c -iI 0.3 - 0.2 I 0.I - a I aw I I A. 2 r I A I I a I I I I 1 I 1 w vw - iAd SHANSEP --- Recornpression 3.0 . i0g __0-- /7 2.o __ -. /I /.0 k , V A. 4O - T ^ IQP #r /o /2 O L 0.7 O./ 0o 2. 4 6 8 AXIAL STRAIN, Ea, % NORMALIZED (8 = 90) STRESS-STRAIN CURVES FROM CIUC TESTS ON SHANSEP AND RECOMPRESSION SAMPLES (OCR 2) FROM EAST WINDSOR 286 FIGURE 6.13 /, _" - -0--- 0.3 No.EC-2-3 /fTest Test /o.ERIC-2-/ T-1 / slppge ,est No.El/C-3-'-indcAted W., ¢c pc",vor O.2 J. 1;-weancsKss _/ S,) UN4 .' --.-CIC 0.1 ---CVC SANSEP e =-s) i n I 6 C rv = r,,(e =+s) I 2 ) I I 4 I I I 8 6 AXIAL STRAIN, I I /0 /2. /4 "2 J4 . % A AX/AL STRAIN, % I 0.1 & x Ir 0.S A 0.4 0.3 -ilo w.- 0.2 0. I I I 2 C I 4% I I I 6 I I 8 AXIAL STRAIN, 4, % I /0 NORMALIZED STRESS-STRAIN C IUC (8 = 45) SAMPLES TEST (OCR = 4) CURVES FROM ON SHANSEP AND RECOMPRESSION FROM EAST WINDSOR 287 FIGURE 6.14 0Z n) w a- 0 w zao w z I en O w -J I-C en It C-) w w z 288 FIGURE 6.15 0 O 0. qf rve 0. or -rbag Irr,, 0. 0. 0 OCR COMPARISON OF 2uc VERSUIS OCR FROM CIUC (8 45), CKoUDSS, AND UU (45) TESTS ON SHANSEP AND RECOMPRESSION SAMPLES FR( )M AMHERST AND EXkST WINDSOR 289 FIGURE 6.16 so - - l - l SYM. MOC 0 SHA NSEP TO 40 RECOMPRESSION Amherst Data i SNANSEP samples had the some 9mf"L) = /.76 X a:m @6 tc =/ dy c =/ day 0c 2'zo 0 Pcotc - a 7nd crvrr= / 7 kg/cm t = 3 days c 7 I/ days 2 OCR 3 I I 5- 6 I 7 G COMPARISON OF avc AT = 1.0% FROM CKoUDSS TESTS ON SHANSEP AND RECOMPRESSION 290 SAMPLES FIGURE 6.17 0.32 5YM.1 TYPE OF TEST o U/C test 0.28 _ V RECOMPRESSION/ C/C tests SHANSEP C/UC tests V RECOMPRESS/ON Ce/ iC -_ _ / C6U£IE tests SHANSEP CKUC / CUIE tests 0.24 0.20 m Ff / SHA NSEP ,t_ °'vm ·II / 0.16 I' I OCR =4 m ', 0./2 sts X ,- _ ! L-JrK = At ' 0.08 0.o0 IUt/ic tests _ ,_ ,, C) I. /0 . I 20 I I I. I I I 0 O I l 30SO60 I I 70 I 80 90 O qf COMPARISON OF °c FROM CIUC AND CKoU TESTS ON SHANSEP AND RECOMPRESSION SAMPLES 291 FIGURE 6.18 7. INTERPRETATION OF ANISOTROPIC BEHAVIOR OF CONNECTICUT VALLEY VARVED CLAY 7.1 INTRODUCTION As presented in Chapter 2, the term anisotropy means that the soil properties (e.g., qf. A, , and C/Ovm) vary with loading direction (defined by angle ; see Fig. 2.1) as they are measured in the laboratory using controlled tests with different directions of alf. It is convenient to divide aniso- tropy as measured in the laboratory into three components, as follows: 1. Inherent Anisotropy--For varved clay, the inherent anisotropy includes: a. Structural Anisotropy: This component is a result of the mode of deposition and subsequent K o consolidation that produces a preferred orientation of particles. K o consoli- dation causes plately shaped particles to have a tendency to align themselves at right angles to the direction of the major principal stress. b. Material Anisotropy: This component of aniso- tropy results only from the layered nature of varved clay, the individual layers being considered as isotropic material. The two components of inherent anisotropy would 292 be expected to lead to changes in effective stress envelope, pore pressure parameter, and modulus with direction of loading. 2. Stress System Induced Anisotropy--This component of anisotropy results from the fact that different increments of shear stress are required to produce failure as the major principal stress varies between the vertical and horizontal directionswhen K o is not equal to unity. In essence, stress sys- tem induced anisotropy results in changes in effective stress as al varies in direction during shear. This component occurs even if there is no change in properties due to inherent anisotropy. 3. Combined Anisotropy--Thisterm (used in place of "in situ" anisotropy because the anisotropic behavior presented in this Chapter is measured via the SHANSEP method of consolidation) includes the total effects of inherent and stress system induced anisotropy. The study presented in this chapter hopes to provide an understanding of the fundamentals controlling anisotropic undrained shear strength behavior. The study concentrates on the anisotropy in qf interpreted in terms of effective stress, the anisotropy in NESE (both at qf and (al/3)max), and the anisotropy in pore pressure parameter A (considered at a particular strain). Some consideration is given to the anisotropy in undrained modulus. 293 7.2 METHOD OF INVESTIGATION To provide this understanding, an attempt was made: 1. To separate the material anisotropy component from the structural and stress system induced anisotropy components so that the anisotropy in qf, A, NESE and E primarily due to the layered nature of varved clay (i.e., the material anisotropy component) could be studied; and 2. To illustrate the general effects of structural anisotropy. Combined anisotropy is studied in terms of effective stress from results of CKoUPSC, DSS and PSE test data, i.e., for plane strain test conditions. Although more extensive data exist for shear in TC and TE, interpretation of the results are complicated by effects due to changes in a2 which are difficult to separate out. Details of the types of tests used for measuring material and combined anisotropy are presented below. Measurement of Material Anisotropy Conceptually, for plane strain loading, CIU PSC tests on samples with different inclinations that have been consolidated to extremely high stresses ( >>>vm ) to minimize the in situ structural anisotropy should be used for this purpose. How- ever, since this was not possible, SHANSEP CIUC tests on samples at different inclinations (=0, 45 and 90 ) at OCR's of 1, 4, and 20 were used to study material anisotropy (i.e., Option 2 294 in Table 2.1). These CIUC tests have some drawbacks. The magnitude of a2 is controlled in tests of this type, but the direction of 02 relative to the varve orientation changes with sample inclination. This complicates interpretation of the results. Also, the values of c used were only 4.0 kg/cm 2 xipared tovm= 2.4 kg/cm 2 for the East Windsor varved clay which is used in the study),which is not high enough to eliminate the effects Therefore, the word of structural anisotropy. material is put in quotes, i.e., "material" anisotropy is used to emphasize the fact that the results are only an approximate measurement of the true material anisotropy. Measurement of Combined Anisotropy Since the anisotropic fabric is oriented in the same direction as the in situ soil and since shear starts from a K o condition, SHANSEP CKoUPSC, CKoUDSS and CKoUPSE tests were performed for this purpose. Note, however, that results for OC CKRUPSC, PSE tests had to be estimated based on trends measured in CKoUC and CKoUE tests. Effect of Structural Anisotropy Component An attempt was made to approximately determine the structural anisotropy component. Conceptually, this component of anisotropy should be shown by comparing qf values from isotropically consolidated PSC tests run on samples with different inclinations with those from CKoU 0 PSC, DSS and PSE tests 295 at OCR = 4 where Ko = 1.0 so that shearing of the CIU and CKoU samples starts from the same conditions. Since this type of plane strain testing was not possible, SHANSEP CIUC test data were used for this purpose. 7.3 INTERPRETATION OF "MATERIAL" ANISOTROPIC BEHAVIOR Test data from CIUC (8=0, 45, 90) tests are plotted in Figs. 7.1 through 7.6 and summarized in Table 7.1. Interpre- tation of the anisotropic behavior arising primarily from the layered nature of varved clay for both NC and OC samples is as follows: (1) The "material" anisotropy in qf/avc of varved clay results from anisotropy with respect to the normalized effective stress-strength parameters (Fig. 7.4), and to the pore pressure parameter Af (Fig. 7.3 (c)), and as a result of this, to the excess pore pressure at failure (Fig. 7.4). seen that the variation in qf with It is is within 20% (Fig. 7.3(a)) and the ratio qf(B)/qf(V) is independent of OCR (Fig. 7.3(b)). qf/Ovc from the horizontal samples are the largest and qf/avc from the inclined samples are the smallest (Fig. 7.3(a)). The inclined (450) samples, which are sheared parallel to the varves, have the lowest NESE at qf (Fig. 7.4) and for NC soil, also the largest Af. Comparing vertical and horizontal samples (4> OCR >1), both being sheared across the varves, vertical loading always develops larger pore pressures and causes a lower NESE at qf (Fig. 7.4). These both result in a lower 296 f vc (2) The anisotropy in NESE at qf when Pf/vm> 7.4) or in 0.3 (Fig. (Table 7.1) is due to "material" (c = O) of NC soil anisotropy and variation in the degree of mobilization of friction and perhaps cohesion during shear. plete mobilization of friction Because of the incom- for vertical loading, NESE at qf is lower than that at (al/a3)max' For horizontal loading, since NESE at qf is equal to that at ( 1 /53)max' it is thought that the frictional component is fully mobilized at qf (Bjerrum, 1973). As a result, NESE at qf for horizontal loading is higher than for vertical loading when Pf/Ovm 0.3. Note that at (al/a3)max' NESE for vertical and horizontal samples are identical. Because failure takes place within a clay layer, NESE at qf for inclined loading is the lowest. (3) The anisotropy in NESE at ( 1/3)max is only the re- sult of whether failure occurs across the varves or within when shearing is parallel to the varves. a clay layer The independency from inclinations of the failure plane (a = 600 in vertical sample and = 300 in horizontal sample) of NESE at (al/3)max for failure across the varves suggests that (al/a3 )max of the clay and silt and c/avm at portions are isotropic. That is, structuralanisotropy does not cause a change in the NESE at (l/a3)max. It then follows that the increase in NESE for failure across the varves (i.e., vertical and horizontal samples) compared to failure within a clay layer (=450 sample) is mainly the result of the increased strength of the silt layer. [CD direct shear test data (see Fig. 2.3 in Lacasse 297 1972) show a higher envelope et al., for failure in a silt layer than in a clay layer, except at very high OCR values.] Furthermore, the NESE at (al/a3)max' for failure across the varves and for failure within a clay layer are considered to be material properties. (4) The anisotropy in pore pressure A at in Fig. 7.5. At the same strain (= 10%), = 1.0% is shown the horizontal samples at OCR's of one and four have smaller A and Au than vertical samples, while results from inclined samples fall between these values. It is difficult to assess whether this behavior is mainly due to material or structural anisotropy, or a combination of both effects. (5) In Fig. 7.6, the increase in E(H) compared to that from vertical and inclined samples is probably due to a lower Au and a larger horizontal drained modulus. An indication of a larger horizontal drained modulus compared to the vertical modulus is obtained from CRSC (constant rate of strain compression test) data on Hackensack Valley varved clay (Saxena et al., 1974). CR and RR of-a vertical sample were larger than those from a horizontal sample at the same depth. In summary, the 'material anisotropy causes: 1. Anisotropy in qf due to anisotropy in both NESE at qf and the pore pressure at failure (qf(H)> qf(V)> qf(4 50 )). The qf( 8 )/qf(V) ratio was found to be independent of OCR. 2. Anisotropy in NESE at qf, though this behavior 298 is also due to variation of friction and cohesion during shear (horizontal NESE > vertical NESE > inclined NESE). 3. Anisotropy in NESE at ia1 /a3)max. This anisotropy, considered to be a true material property, depends upon whether failure occurs within the clay layer or across the varves, the latter leading to a significantly higher failure envelope. 4. Anisotropy in excess pore pressures, these generally being largest in vertical samples and lowest in horizontal samples. 5. Anisotropy in (Eu(H) > E(V 7.4 E u at the same strain ( = 1.0%) EU(450) . ) EFFECT OF STRUCTURAL ANISOTROPY COMPONENT Figure 7.7 shows a plot of qf/vm versus at OCR's equal to 1 and 4 from CIUC tests on samples with different inclinations and from CK UPSC, CKoUDSS and CKoUPSE tests (results presented in Table 7.2). The shaded area for the OCR=4 data represents the combined effects of structural anisotropy and variations in 2. For OCR = 1.0, the shaded area also includes the effects of stress induced anisotropy and of shearing samples which have different initial shear stresses, since K is less than 1. In Fig. 7.8, an estimation of the struc- 0 tural anisotropy component is shown. versus Plotting qf(a)/qf(V) , where qf(V) is from CIUC ( = 0) and CKoUPSC tests, 0 299 is an approximate method for adjusting CIUC test qf values to equivalent CIUPSC test conditions as discussed below. As previously stated, the structural anisotropy component effect, at least conceptually, would be shown by data at OCR= 4 (i.e., when K = 1) from CIUPSC tests on samples with dif- ferent inclinations and from CKoUPSC, CKoUDSS, and CKoUPSE However, it is reasonable to assume that qf(V) from tests. "CIUC PSC (=0)" since K and CK UPSC tests would be essentially equal versus isotropic consolidation showed little effect on CU TC strengths (Section 53.1). In essence, Fig. 7.8 ob- tains the equivalent qf from the plane strain condition by increasing and 90 qf values for CIUC samples at inclinations of 0, 45, by a factor equal to qf(V) from CKoUPSC te.st qf(V) from CIUC (=0) test [Therefore, for example, the estimated qf from a CIU PSC (8=45) test is equal to qf from CIUC (8=450) test qf from qf(V) from CXKUPSC test qf(V) from FmIc (0=0) qf from CIUC (8=45 ) test (=0) test qf(V) from cIc and ] CPSC. x .).test (..=.45 test Also, there is no stress sys- tem induced anisotropy when K = 1. Thus, Fig. 7.8 represents an estimate of the effect of structural anisotropy on undrained strength. As shown in Fig. 7.8, it is seen that structural anisotropy significantly decreases qf for inclined and horizontal loading and therefore increases the anisotropy in qf over 300 that due to material anisotropy. The increased anisotropy in qf is probably due to changes in anisotropy in NESE at qf and the pore pressure response,but these effects are difficult to estimate. 7.5 INTERPRETATION OF COMBINED ANISOTROPY The combined anisotropy in qf, Af and NESE from CUPSC, 'CK UDSS, and CK UPSE data (4 > OCR > 1) are presented in Figs. 0 0 7.9 and 7.10 and Table 7.2. The method used to estimate the OC qf values was presented in Section 5.3.3 and Fig. 5.24. Af was computed* from Ko values (.seeFig. 5.2) and estimated locations of NESE at qf (presented in Section 5.3.3). In Fig. 7.10, the locations of NESE at qf and at (l/a 3 )max for NC and OC CKoUPSC and CKoUPSE samples are estimated as follows: 1. As shown in Fig. 5.22, the NESE at qf when f/avc> 0.3 for NC and OC CKoUPSC samples was estimated to be slightly above the NESE at qf for NC and OC CKoUC samples based on NC CKoUPSC test data. At (a1 /a3)max' the NESE values for failure across the varves (a material property) is believed to hold for NC and OC CKoUPSC samples. 2. The NESE at ( 1 /O3 )max for failure across the varves is believed to be the same as the failure envelopes at qf and at (1l/'3)max for NC and OC *The values are sensitive to the assumed location of the NESE, especially at OCR=4. 301 CKoUPSE samples, i.e., for these samples, the envelopes at qf and ( l/ 3)max are identical. With help from the study presented in Sections 7.3 and 7.4, interpretations of the combined anisotropy in qf, A, and NESE of NC and OC samples (4 > OCR > 1) are as follows: 1. The combined ansiotropy in qf/avc (Fig. 7.9) results from: a. Anisotropy with respect to NESE at qf (or the anisotropy in (c=0) for NC samples, Table 7.2); b. Anisotropy with respect to the pore pressure parameter Af (Fig. 7.9), and c. Differences in the magnitudes of Aqf due to the rotation of principal planes (i.e., the stress system induced anisotropy component) when K is less than 1. The anisotropy in Af and the changes in Aqf in turn lead to further anisotropy in the pore pressure at failure. qf(H) is slightly smaller than qf(V) even though the NESE at qf is much higher for horizontal loading. The decrease results from signi- ficantly lower effective stress at failure. This occurs even though Af for horizontal loading is lower, as illustrated below for data on NC soil. 0 -m Type of Test Pf/a f -ve A -cf CK UPSC 0.70 1.09 23.5 CKoUPSE 0.55 0.85 27 302 The significantly lower qf/avc for inclined loading in DSS tests results both from a lower NESE at qf (Fig. 7.10) and probably from a lower value of Pf/avc For NC soil, the DSS pfavc is 0.49 (Fig. 5.33) compared to 0.55 for PSE. 2. As previously discussed, the anisotropy in A is due to both the material and structural components (i.e., due to inherent anisotropy). A at = 0.3% and Aq/Aqf = 1/2 for NC CKoUPSE are smaller than for CK0 UPSC as shown below. Type of Test 3. A ate= 0.3% A at Aq/Aqf=1/2 CK UPSC 1.02 0.80 CKoUPSE 0.45 0.52 The anisotropy in NESE at qf, when NESE at qf is not equal to that at (al/a3)max, or the anisotropy in Mohr-Coulomb at qf of NC soil are the result of inherent anisotropy and of variation in the degree of mobilization of friction and cohesion. For fail- ure across the varves, since the mobilization of friction and cohesion are strain dependent, the much larger f of a NC CK UPSE test compared to that of a NC CKoUPSC test (f = 4.0%versus0.4%)partly explains why 4 at qf from a horizontally loaded sample is larger. [Note that NC ~ at qf and at (l/a3)max from TUR7PSE tests are identical (Table 7.2).] Because failure occurs within a clay layer instead 303 of across the varves (i.e., the material anisotropy component), the NESE at qf from CKoUDSS tests is the lowest. The fact that a larger difference between NESE at qf from vertical and horizontal loading is obtained from CKU plane strain compres- sion and extension tests than from CIUC tests on vertical and horizontal samples (comparing Fig. 7.4 to Fig. 7.10) might suggest that the structural anisotropy could cause the anisotropy in NESE. 4. The anisotropy is NESE at (al/a3 )max is only due to the material anisotropy component, i.e., failure across the varves versus failure within a clay layer. Based on several types of tests reported in Chapter 5, NESE at (al/a3)max for vertically and horizontally loaded samples are identical. Thus, the lower f at (/a3)mx from NC CK UPSE compared 1 3 max o to CK0 UPSC (Table 7.2) is due to larger p/avc of the CK UPSE Sample. For the sake of completeness, the combined anisotropy in undrained shear modulus is shown in Figs. 7.11 and 7.12 by comparing test data from CK UDSS(C), CK UDSS, and CK UDSS(E) tests on NC soil. At low stress levels, inclined loading re- sults in a lower modulus than for either vertical or horizontal loading. But at the higher shear stress level, little modulus anisotropy is measured in this type of testing. 304 This contradicts the results shown in Fig. 5.27 from PSC and PSE tests, but these data may be influenced by apparatus friction. 7.6 SUMMARY AND CONCLUSIONS The factors that control anisotropic strength behavior of varved clay are the layered nature of the soil (the material anisotropy component), the prior K o consolidation (the structural anistropy component) and the stress system induced anisotropy, especially important when Ko is low. of the combined anisotropy in qf, A, Au, Coulomb Interpretation and c/avm (or Mohr- and c) of NC and OC samples ( 1< OCR < 4) as shown fro the SHANSEP method of consolidation are as follows. 1. The anisotropy in qf results from anisotropy in effective stress at failure and in NESE at qf. Due to material anisotropy component, qf(H) of NC and OC samples is the largest. With the additional effects of structural and stress system induced anisotropy components, the anisotropy in qf increases from that due to the material anisotropy component and qf(V) from CK-UPSC tests is larger than qf(H) from CKoUPSE tests. The lower qf(H) compared to qf(V) from CKoU plane strain tests results from the lower pf of the CKoUPSE sample, though the NESE at qf is higher. Mostly because of having the lowest NESE at qf, qf for inclined loading is the smallest. 305 2. The anisotropy in NESE at qf, when NESE at qf is not equal to that at (l/a3)max' is due to inherent anisotropy component and variation in the degree of mobilization of friction and cohesion. For vertical loading, because of the incomplete mobilization of the friction and cohesion components of strength, NESE at qf is lower than that at (1/a3)max with NC soil. For shearing across the varves, be- cause of differences in the degree of mobilization of friction and cohesion, NESE at qf for vertically loaded samples is lower than that for horizontally loaded samples. This lowering is also due to the structural anisotropy component. Because failure takes place within a clay layer, NESE at qf for inclined loading is the lowest. 3. The anisotropy in NESE at (al/aC3)maxis only dependent upon whether failure occurs within a clay layer or across the varves. Thus, the anisotropy in NESE at (a1/a3)max is only due to the material anisotropy component. Despite having the same NESE at ( 1 /a3 )max , at ( (=0) 1 /a 3) ax for NC CK 0 UPSC tests is larger than that from CK0 UPSE tests, because P/vc 4. at (1/C3)max is smaller. The anisotropy in pore pressure is due to anisotropy in A resulting from the inherent anisotropy and from differences in the magnitudes of Aq. 306 Due to the material anisotropy component, at the same strain, A for vertical loading is generally the largest and A for horizontal loading is the lowest. However, at the same strain, despite having a lower A, a CKoUPSE test can have higher pore pressure and a lower p/avc than a CKRUPSC test because of the much larger Aq. 307 -11 -q to C O .H >4 - Pr 0 0 >: 4 4i . ts L o v D Iw I I 0 r I o I.- H e~ 0 ltI > > > N N N N 0 o 0N H H H ,.-.I O oo N N CI 0Hjl o o 0 o or o- O 0 O o 0 0 n Ln Ln I I oI o O W H ' C' U Pu Ib DJ H rI 0 MI ° co I o E E-, o. , o 00 oCo %O o LA 0 4r 0 E. In cLn A Al O NN O~ L t CO N trNmN rl O 0 I*' 0 o 0rI 0o 0co O r l rl rl . 10 0 ,. L, r- C; ,, r m Co 0) a> CD C ,. '0 N LA N 0 H 0 C 0 (PI(d -4J4 ) EnU) WqH 00 UH H 0t, (d to Vz -H .-H 54k 1' r' 4Hi P Ln c11 oo Ln 00 LA 0 tU . ,o o Ln U) o 4 ; F' H 0 O _.b o O D vI . o; o :>4 > _.. C; 0NV LA w 0a cn Ln 0 o 0 E _- 308 CA N1 II Ln Hl °0C Z '" w t:: 0 to d (1,v, -) 4) lb s440 C aD). > 0 0 o : Lo H o I trq 0o N Cf. W dP U: p4 4 4 dP U) ~~~, ~ ~ > o 0% o O Ln *w or a LA 0 oi 4I O 2z _ Table 7.1 w U) P M 0 0 U) 4-41 r~4 Cd U) a) u a U) -,-) 9l) In U) 0 m E-1 c H X U u >4 Z 0a md IO a to w (n I I I I L I I a) Cd ,)0) .r-i 4-) U) U E c ----II 'n 0D r- O O O O O o o o o o o N 0 o o - O N N m ri I I I I I I -o 00 IU O Ln c4 5 E-4 I m E N 444 * o o O O O o N qg S N rN H H or o m ,- N ~-C N -co N 00 0 ,-I - H -.I c0 CN O0 rI In C o CO CO C O --I m N m CO r-4 r- o o .4J 4) O ( O N CO *,1 U) .-i o 0 O CI r-I O ro crrq o -- -CO H H H oN uL o oO 0 0 0 H 0 U 0 a M N L() co W trIIt5 - H H O _ m m 0 o *O 0 <H X U) E-4 U) Ln .lN H- CoN - -- - | I-I·_- -- r- O rN *4- H4 N -I Ib w - o N r- O o 1I-6 LO -H ., II~- L l 1t H M · LII·.-- IU _O H r74 ain 0 3E-1 --- to ,1U) .r w U) 0 Cd ro U) :D P: Cd 4J gW z U H Z U) a) a) H .I Ofi U) U) U) Ur) a) to 01) 0 0 H In U) uU W Z m 0O 4-4 U) v O o C) IIIIII N m 0 3 m ca m U] c N o" 40 Rrn N- 0 m m z Table 7.2 I 309 ·_ /. O a08 '4 I, IP I4 0.6 0.4 o0. --0 2 4 6 8 o/ AXIAL SRAIN, 6 % /4 I, A Y..J 3.0 cr 3 .2.0 AXIAL STRAIN, ,% EFFECT OF SAMPL.E ORIENTATION ON STRESS VS STRAIN FROM CIUC TESTS ON SAMPLES OF NORMALLY CONSOLIDATED EAST WINDSOR VARVED CLAY 310 FIGURE 7.1 I AXIAL STRAIN, 4 % , - 3 AX,'AL STRAIN, F, % EFFECT OF SAMPLE ()RIENTATION ON STRESS VS STRAIN FROM CIUC TESTS ON SAMPLES OF OVERCONSOLIDATED (OCR 4.0) EAST WINDSOR VARVED CLAY 311 FIGURE 7.2 A U.9 0.3 0. O. 0 0 (a) 14 /.2 q~yg) ,?f(y #?depe17de7t, Of OCR /.0 0.8 I 7o /0 20 30 I 40 I 50 60 I 70 I I 80 90 / /9 (b) I.. , Af, 9 ), 'OR =/ /.0 Af (g. 0 II n4 0 I cI) -, I I II I /0 I i 20 30 I I I I 0 0 I -- laa ANISOTROPY IN AND Af VARVED CLAY RESULTING FROM COMPONENT 312 --- -II 60 O CR = 4 I I 70 I I 80 90 /00 (C) OF CONNECTICUT VALLEY MATERIAL" ANISOTROPY FIGURE 7. 3 z 0z cn z uZ _ -- UC)Z L N ZL Q 0_ >. ·. LiJ ~J ZL ~b 'N 313 FIGURE 7.4 0.6 1 0.* OCR = OC: o'vm at .1 -Iv =o/.0% 0.2 $ OCR 4 I ii 0 o /I /o I o Iv I& , 3o 40 Ii 5 II 60 I-- - I I 70 8o 90 o0 (Q) I v 1. . /.0 A at E- 10% 0.5 - /0 - 20 30 40 SO 60 7 WJhS0 f(b) "MATERIAL' PORE ANISOTROPY PRE'SSURE IN POR E PRESSURE PARAMETER A AT 314 AND :1.0% FIGURE 7.5 450 A 3SS o From C/ZC D From cTC r-e5) EH - Ev = EX at & 5% From C//C (eo=90) test = (e = o) test /A test Horizontal Undrained Modvuus Verticol t/ndroined Modulus / Inc//ned Moduis 2at . / EH (e= 90) / E(,, - o) ISO I ,/ I,{C 20 so OCR ANISOTROPY IN UNDRAINED CIUC TESTS 315 MODULUS FROM FIGURE 7.6 I ,o rnfMDA^DIK A llnTDDYV Vl.vlr VII r l I. r(VI PI1IV SI IV I Il Im FROM PLANE n L-LV %,f MF'AI IVL-I , VIICr STRAIN AND CIUC TESTS FIGURE 7.7 _ _ 2.0 /.8 1.6 /.4 f (V) /.0 0.8 0.6 0.4 1o EFFECT OF STRUCTURAL ANISOTROPY COMPONENT ON ANISOTROPY IN qf 317 FIGURE 7.8 0.4 ---- 0.3 I OCR =/ -*---- OCR OCR 2 - OCR=4 estimated } I Er.m V., II, /o 20o I 3 , 40 SO la 60 70 80 I 90 1.0 , qf(v) a0. 0.7 0.6 8.5 6.5 AsF(v) Af(v) 4.5 I-, \~~ 2.5 II - I I1 20 I I° 40 .o L 60 I I 0o /00 COMBINED ANISOTROPY IN qf OF CONNECTICUT VALLEY VARVED CLAY MEASURED FROM CKoU PLANE STRAIN TESTS 318 FIGURE 7.9 z ,[ (X) w z 0. 0 LL w U) w z z >- 0 (nI 0Z W Z 0O X O 0 w U bon Eo . IG 319 _ FIGURE () W 7.10 . b6 50 40 G (e) rrvc 30 20 /0 4.5comprssion) 0 Ad O Li 29 -fr'extension) ( 90 G ANISOTROPY WITH RESPECT TO avc OF NORMALLY CONSOLIDATED EAST WINDSOR VARVED CLAY AT VARIOUS APPLIED SHEAR STRESS LEVELS 320 FIGURE 7.11 60 Initia/ tongent mo duls / so KtN%.-- , 1· I - ace__0 40 ve) X-a/i 30 I 20 From CouIDSS tests Jr _- 45 0(cmpeessioon) o 0 ___ -5° fe xtension) B= 90 ° (3=29° G ANISOTROPY WITH RESPECT TO c OF NORMALLY CONSOLIDATED EAST WINDSOR VARVED CLAY AT 6 .1% 321 FIGURE 7.12 8. EVALUATION OF UNDRAINED STRESS-STRAIN-STRENGTH PROPERTIES OF CVVC FOR USE IN DESIGN 8.1 OBJECTIVES AND SCOPE The purposes of this chapter are: (1) to present best estimates of the normalized stress-strain-strength parameters for use in the design of structures on Connecticut Valley varved clays, with the background showing how these parameters were developed; and (2) to recommend suitable testing procedures for developing anisotropic S /a u v parameters for other varved clay deposits. The normalized stress-strain strength parameters are for the following analyses that might be included as part of the design process of structures ,Specifically an embankment) constructed on Connecticut Valley varved clays. 1. Total stress stability analyses to determine the factor of safety for undrained and partially drained conditions. Table 8.1 summarizes recom- mended uses for total stress analyses. 2. Analyses to predict stress, pore pressure, and deformation due to undrained loading. Recommended parameters such as A- and E -are presented to use with available chart solutions and with MIT's finite element program FEECON. meters.) (See Table 8.2 for required input soil para- The parameters for estimation of initial settlement based on D'Appolonia et al. (1971) method presented in Table 8.3. Soil parameters for effective stress stability 322 analyses for drained and undrained conditions, and those for predicting the amount and rate of long term not presented here. settlements are However, such information can be obtained from Ladd (1975). The material presented in this chapter will concentrate on the background for the development of the soil parameters which is based upon the study presented in Chapters 4 through 7 (including the use of normalized FV data) rather than presenting the details of methods of analyses. Since the background for the development of soil parameters of Connecticut Valley varved clay is fully discussed, this approach can also be extended to develop normalized anisotropic Su parameters for other varved clay deposits, presented in Section 8.6.2. 8.2 DEVELOPMENT OF UNDRAINED STRENGTH PARAMETERS OF CVVC FOR TOTAL STRESS STABILITY ANALYSES USING SHANSEP Two requirements for obtaining reliable estimates of factor of safety from total stress analyses are: 1. The use of a suitable method of analysis; and 2. The selection of suitable undrained shear strength values which are compatible with the method of analysis and reflect in situ soil behavior. Since the undrained shear strength behavior of varved clays is highly anisotropic, the method of analyses should be capable of taking this anisotropy into consideration. The Morgenstern and Price (1965) method of analysis (M-P) or similar "generalized" 323 methods, is recommended for. all cases involving the input of anisotropic undrained strength data. Strength data obtained from the SHANSEP method of consolidation will be used for developing the design Su parameters for the reasons given below. 1. It is thought that the SHANSEP method should yield better Su values for NC clays than the RECOMPRESSION method, and also give reasonable estimates of Su for OC deposits. 2. NSP for different varved clays located in the Connecticut Valley as measured in several types of tests using the SHANSEP method of consolidation are practically identical. This section presents: (1) a recommended method for ob- taining suitable anisotropic undrained shear strength parameters measured with the SHANSEP method for use with M-P analyses; and (2) recommended values of SHANSEP anisotropic undrained shear strength parameters to use in the design of structures on Connecticut Valley varved clays. 8.2.1 Criteria for Developing Design Undrained Strength Parameters Values of undrained shear strength parameters should be theoretically compatible with the method of analysis (e.g., Morganstern-Price (M-P) analyses as recommended in this thesis) and also reflect in situ behavior. The various factors that need to be considered in developing appropriate design values of Su for total stress analyses are as follows: 324 1. The need to consider the anisotropy in qf--As shown in Chapter 7, the values of peak strength and stress-strain characteristics are directional dependent. Though tnese properties can be mea- sured for various loading directions, a practical method (e.g., that proposed by Ladd (1975) in Fig. 8.1) for considering anisotropy and other factors is needed. 2. The suitable definition of undrained shear strength for M-P analyses--M-P analyses accurately analyze failure surfaces composed of straight lines. Therefore, the un- drained shear strength for such analyses is defined as the shear strengthon the failure plane. In order to reflect in situ behavior and since effective rather than total stresses control this behavior, it is appropriate to adopt the inclination of failure planes from the effective stress Mohr-Coulomb failure criteria (i.e., the inclination of failure plane with the major principal plane is(45 + /2).* Consequently, for failure at the peak strength (qf), the shear stress on the failure plane, Tff, for a given mode of failure (PSC mode for vertical loading, DSS mode for inclined loading and PSE mode for horizontal loading), is equal to qf cos ( at the *Observations in the laboratory indicate that the inclination of failure planes, if visible, with the direction of the major principal plane is more than 450 (predicted by a total stress Mohr-Coulomb failure criteria) and is close to 45 + /2 ( at (al/a3)max) 325 qf condition. 3. The strain rate effect--The stress-strain characteristics and hence qf are dependent upon the strain rate, a decrease in the rate of strain decreasing qf. uncertain. The magnitude of this effect is However, based on information from Ladd et al. (1977), it is thought that the slower in situ strain rate compared to that used in these CKoU laboratory testing programs should cause relatively little reduction in qf. 4. A correction for strain compatibility--Because of anisotropy in stress-strain-strength properties of soil, it is unlikely that the peak strength (qf) for varying mode of failure can be simultaneously mobilized in strain softening material since these peaks occur at different strains. formation of a distinct failure In fact, the (slip) surface throughout the foundation soil is thought to be primarily a function of the strains which occur. Ladd (1975) proposed a method (Strain Compatibility Method) to account for strain compatibility assuming that the shear strains along a potential failure surface are equal. Note, however, that this assumption is not based on theory or observation. 326 8.2.2 Anisotropic S Parameters Developed by Ladd (1975) This section presents Ladd's (1975) basic approach for obtaining anisotropic Su design values. This was done before all test data (especially for horizontally loaded samples) presented in this thesis were available. The basic approach is as follows: 1. For simplicity, the three types of failure surfaces and corresponding strength shown in Fig. 8.1 are recommended for considering Su anisotropy for use with the M-P method of analysis. 2. The definition of undrained shear strength is that previously defined in Section 8.2.1. qf cosT for PSC and PSE modes and Tff Thus, Tff in the DSS mode is assumed to be equal to Thmax. 3. The strain rate effect is not considered. 4. The strain compatibility effect is considered by using the strain compatibility method described below. The recommended anisotropic Su values from three modes of failure are considered to be equal to the laboratory measured shear stresses which yield the maximum average shearing resistance that could be mobilized at the same shear strain for the three modes of failure. The shear stresses and shear strains are determined as follows. (a) The value of shear stress on the potential failure plane at a particular strain for either PSC or PSE modes of failure is equal to q cosT. 327 The values of cosT selected were: Mode of Failure OCR cosT PSC 1 >2 0.92 0.90 PSE >1 0.90 (b) The shear stress on the potential failure plane at a particular shear strain for the DSS mode is equal to Th. (c) To obtain shear strains, the measured vertical strains for PSC and PSE samples is multiplied by 2 (i.e.,y=2 e vertical). In DSS tests, Y is equal to the horizontal displacement divided by the height of the sample. Table 8.4 shows how SHANSEP anisotropic Su values at OCR1.0 were determined. It is seen that the average maximum mobi- lized resistance, which occurs at a shear strain of 6%, is 8% less than the average of the peak shear strengths. At this strain, Su for PSC is significantly less than the peak vertical shear strength (0.258), due to the strain softening. Su is at Tff (= T hmax =0.16). The DSS The 6% shear strain is not large enough to fully mobilize the peak horizontal shear strength (0.225). In essence, for considering strain compatibility, ff values for PSC and PSE were reduced by 16% and 6% respectively, i.e., the strain compatibility factor (SCF) have values of 0.86 and 0.94 respectively. For the DSS modes, the SCF is equal to 1.0. For OC soil, since the laboratory plane strain stress328 strain-strength data were not available, OC qf values for PSC and PSE were estimated from very limited TC and TE results (using a method similar to that presented in Fig. 5.24). SR values for OC PSC samples used by Ladd (1975) are essentially the same as those presented in Fig. 5.24. However, qf(H) for OC PSE samples was estimated by assuming that K was equal to 0.89 independent of OCR. (Ks = qf(H)/qf(V)) This means that the same* relationship of SR versus OCR was used for vertical and horizontal loading. To consider strain compatibility, the follow- ing values of SCF were used based on stress-strain behavior observed with other clays. SCF 5. Avg. SCF OCR PSC DSS PSE 2 0.925 1.0 0.975 0.967 4 1.0 1.0 1.0 1.0 Finally, Ladd (1975) arbitrarily reduced the design strength by 5%, i.e., Su=qf cosT x SCR x 0.95. 8.2.3 Design Parameters Developed by the Author The basic approach used by the author for developing ani- sotropic Su design parameters generally follows that proposed by Ladd (1975), with the exceptions that: 1. The method for estimating OC SCR for each mode of failure is different. The author used results from triaxial tests (details given below). 2. A strain rate effect is considered. A strain *As shown in Fig. 5.24, SR versus OCR relationships for PSC and PSE are not the same. 329 rate factor of 0.95 is arbitrarily selected for Connecticut Valley varved clays. (Note that based on Ladd et al. (1977), Aqf/Alog tf A< 0.5%/hr.) 3. Thus, 10+5% at < u=qf cost* x SCF x 0.95. The OC qf values for PSC and PSE were estimated from Fig. 5.24. This gives the same qf(V) but different values of qf(H) compared to Ladd (1975). SCF values for NC soil are those from Table 8.4. The basis for estimating SCF for OC (OCR=2 and 4) soil is as follows. Comparing Tables 8.4 and 8.5, it is seen that the average SCF at OCR = 1.0 for plane strain and triaxial tests are essentially identical, i.e., by using the stress-strain-strength data from CKoUC, CKoUDSS, and CK UE tests. tests, is equal to 1.5 (For CKoUC and CK UE vertical and the shear stress on the potential failure plane at a particular strain is equal to cost.) q Note, however, that SCF values from PSC and PSE are difFurthermore, for ferent respectively from those from TC and TE. both triaxial and plane strain loadings, SCF for the DSS mode is always equal to unity. On the basis of the NC data, the esti- mated OC average SCF values for plane strain loadings at OCR's of 2 and 4 are assumed to be equal to those from the triaxial loadings, shown in Tables 8.6(a) and 8.6(b). The OC SCF for the DSS mode was assumed to be equal to unity. Details of how SCF for OC (OCR=2 and 4) PSC and PSE modes, and hence Su values (Table 8.7), were evaluated are given below. *cost values are identical to those proposed by Ladd (1975). 330 1. At OCR=4, since the average SCF is practically equal to 1, and since it is thought that the OC CKoUPSC sample should not exhibit significant strain softening, SCF for the were selected 2. PSC and PSE modes to be 1.0. At OCR = 2, SCF values for PSC and PSE modes are determined from the average SCF value from triaxial loading (avg. SCF = 0.96) and from the estimated SU(H)/Su(V) ratio. As shown in Table 8.7, at OCR's of 1 and 4, this ratio is equal to 1.05. Thus, at an OCR of two, it is reasonable to adopt Su (H)/ S u(V) = 1.05 for the determinations of Su (V) and S (H). Table 8.8 compares u values recommended by the author and by Ladd (1975). It is seen that the only difference is in Su(H) at OCR's of 2 and 4 '(the author's S(H) being 9% larger at OCR = 4 and 6% larger at OCR = 2). 8.3 COMPARISON OF THE USE OF SHANSEP ANISOTROPIC Su VERSUS CORRECTED FV STRENGTH DATA 8.3.1 Introduction The objectives of this section are to present: 1. The background of how the correction factor p is estimated; and 2. Checking of the compatibility of using recommended SHANSEP strength data with M-P analyses for undrained total stress stability analyses. 331 This is done by comparing factors of safety from the simplified Bishop circular arc analyses with corrected field vane strengths and from M-P analyses with Ladd's (1975) SHANSEP anisotropic Su parameters. (Note that since che author's recommended anisotro- pic Su values are only slightly different from those recommended by Ladd (1975), the conclusions drawn from using Ladd's (1975) recommendation should also hold with the author's anisotropic Su parameters.) 8.3.2 Recommended Correction Factor () For Connecticut Valle Varved Clay According to Bjerrum (1972), the correction factor em- pirically relates the field vane strength data to the value of the average in situ undrained shear strength on an assumed circular arc failure surface obtained from total stress analyses with = 0 and c = field vane strength. nature, reliable values of Because of its empirical can only be determined from case studies. The basis for recommending two soil and values ( = 0.85 for OC = 1.0 for NC soil) for CVVC is as follows. (1). The recommended i= 0.85 for OC clay is based on case studies at Amherst and Northampton. The average OCR's of the foundation clay within the critical zone at these two locations were approximately 3.5 at Amherst (ranging from 1.5 to 8) and about 2 at Northampton. Thus, the correction factor of 0.85 was developed for moderately to heavily OC clay. (2) The recommended =- 1.0 for NC clay is based upon the trend established from a comparison of the average SHANSEP anisotropic design shear strength parameters with corrected and 332 uncorrected field vane strengths (Table 8.8). At OCR's of 2 and 4, (i.e., within the OCR range of the case studies), the average SHANSEP design S/Zvc from both Ladd (1975) and the author is close to the corrected FV strength using p = 0.85. However, at OCR = 1.0, the average SHANSEP Su/vc at 0.19 is equal to measured field vane strength (Su/Uvc = 0.19). fore, the value of There- for NC soil is taken to be equal to 1.0. Since the use of corrected field vane strengths with Simplified Bishop circular arc analyses is an empirical approach and since the value of is dependent on several factors (e.g., strain rate, anisotropy, strain compatibility, etc.), its use has limitations which are discussed below. (1) The value of is dependent upon the geometry of the failure surface and hence the geometry of the embankment. Because of the anisotropy in Su, the average shear strength along a long, shallow wedge-type surface will be different from that along a deep circular surface. Thus, an embankment with wide berms would require a different correction factor U from one without berms. (2) The value of u is dependent upon the stress history of the site. The anisotropy, the strain rate and the strain com- patibility effects are dependent upon OCR. Plane strain data from Boston Blue clay (see Chapter 2) show that qf(H)/qf(V) increases with increasing OCR, though a much smaller increase was observed from estimated data for the Connecticut Valley varved clays (see Chapter 7). Furthermore, the use of circular arc analyses with corrected 333 field vane strengths for total stress stability analyses for the partially drained case is not reliable. 8.3.3 Compatibility of Using SHANSEP Anisotropic S Analyses with M-P To check the compatibility of using SHANSEP anisotropic Su with M-P analyses, it is necessary to see if the M-P analyses with SHANSEP strengths yield about the same factor of safety as that determined from the Simplified Bishop analyses with corrected field vane strengths. Note that the correction fac- tor was determined from case studies. Figure 8.3 compares values of the factor of safety and the locations of the critical surface of an embankment, used in a design problem presented in Ladd and Foott (1977), from M-P analyses with Ladd's (1975) SHANSEP anisotropic strength parameters and from Simplified Bishop circular arc analyses with corrected field vane strengths. equal to 0.85. The correction factor was Since the stress history, soil profile, and the geometry of the embankment used in the design problem are somewhat similar to those from the case studies, the fact that the factor of safety from Ladd's (1975) SHANSEP S is slightly lower than that from the corrected field vane strengths, and that these values of factor of safety are equal to or very close to 1,suggests that Ladd's (1975) SHANSEP Su values used with M-P analyses are suitable to determine the factor of safety from total stress stability analyses for Connecticut Valley varved clays. Since the difference between Ladd's (1975) and the author's 334 Su values is only the value of S(H) OC S (H) is about 10% larger), for OC soil (the author's the factor of safety using the author's recommended Su values with M-P analyses should also be suitable. Comparing Su values from triaxial loading, Tables 8.5, 8.6(a), and 8.6(b) to those from Ladd (1975) (Table 8.8), the use of Su values from triaxial testing with M-P analyses will be conservative. 8.4 EVALUATION OF UNDRAINED SHEAR STRENGTH FOR TOTAL STRESS ANALYSES IN PRACTICE The objective of this section is to recommend practical methods for evaluating the undrained shear strength of Connecticut Valley varved clays for total stress analyses used in undrained and partially drained cases (Table 8.1). This informa- tion is partly extracted from Ladd (1975). 8.4.1 Initial Undrained Shear Strength for Total Stress Analyses (Undrained Case) The factor of safety for the undrained case determined by total stress analyses can be obtained from two approaches: 1. Corrected Geonor field vane strengths with Simplifie.d Bishop circular arc failure analyses. 2. SHANSEP anisotropic shear strength parameters determined from Section 8.2 (Fig. 8.4) with M-P analyses. Since the correction factor for Connecticut Valley varved clays 335 (presented in Section 8.3) is believed to be reasonably reliable and since the critical failure surface from Simplified Bishop analyses can easily be determined using computer programs, such as LEASE (Bailey, W.A. and Christian, J.T., 1969), the first approach is generally recommended for determining the initial factor of safety. However, as previously discussed ments with long berms, since the values of for embank- can be affected by the geometry of the slip surface, the use of the values re- commended in Section 8.3 may be unsafe. Since field vane strength data generally show some scatter, sufficient Geonor field vane tests should be performed to determine the change in Su(FV) with depth, and to ascertain whether or not there is a significant lateral variation. Upon knowing the stress history of the site, the plot of S (FV)/avc versus OCR (Fig. 8.4) can also be checked. Section 8.6 presents re- commended types of laboratory tests and also Geonor field vane tests for checking pertinent soil parameters. 8.4.2 Undrained Shear Strength for Total Stress Analysis in a Partially Drained Case Total stress M-P analyses with SHANSEP anisotropic un- drained shear strengths are recommended for determining the factor of safety for the partially drained case (Table 8.1) for three reasons. 1. SHANSEP undrained strength data can reasonably be used for estimating the gain in Su with consolidation for stability analyses, even though consolidation of the foundation clay under the embankment 336 will not conform to K consolidation. The error in vertical undrained shear strength should be minor (Section 5.2.3); Su(DSS) should increase when consolidated with a horizontal shear stress (Ladd and Edger, 1972); and the horizontal undrained shear strength should be unaffected since this portion of the failure plane will usually lie beyond the influence of consolidation from the embankment. 2. A method of analysis whereby the difference in Su with different failure surface inclinations can be taken into consideration is needed. 3. M-P total stress analysis is relatively simple compared with effective stress analyses. Further- more, because of the difficulty in predicting the pore pressure at failure, effective stress analyses are not recommended. For the evaluation of Su for M-P analyses of the partially drained case, the following 1. steps are recommended. Determine the initial stress history, i.e., a vo and a prior to construction. vm 2. Compute the increase in total vertical stress Aav versus depth at representative locations using elastic theory. 3. Determine the degree of consolidation, U, versus depth corresponding to the time at which the factor of safety is required. 337 4. Compute the increase in the vertical stress, AOvc' versus depth at representative offsets from Aa UAav 5. + Avc versus depth (i.e., vc = vc vo vc assume that o does not change during undrained v Compute loading). Though this is not absolutely correct, the error is unimportant compared to other uncertainties in the analyses. 6. Divide the foundation clay into zones having the same 7. vm and vc versus depth. Compute values of the anisotropic Su for the appropriate modes of failure (i.e., PSC, DSS, PSE) within each zone using the Su/vc versus OCR = avm/vc curves plotted in Fig. 8.4. Ladd (975) presents an example problem using the above proce- dure for computing the factor of safety for the partially drained case. The evaluation of S u from SHANSEP anisotropic shear strength parameters (Fig. 8.4) requires an accurate evaluation of the stress history, i.e., a and . The value of the initial in vo vm situ vertical effective stress ( vo) is determined from measurement of total unit weights and the pore pressure conditions. The latter requires a knowledge of the elevation of the water table and a check to determine whether or not the pore pressures are hydrostatic. The maximum past pressure, avm' is commonly evaluated from the results of consolidometer tests. discussed appropriate methods for estimating a vm sion curves. 338 Ladd (1975) from compres- 8.5 RECOMMENDED PARAMETERS FOR UNDRAINED ANALYSES OF PORE PRESSURE AND DEFORMATION The objective of this section is to present soil parameters to be used in making predictions of pore pressure and undrained deformations. Either one of the following two approaches, dis- tinctly different in their level of sophistication and amount of information yielded, is recommended for such predictions. The first approach (Table 8.3) employs hand calculations and the theory of elasticity corrected for effects of local yielding (D'Appolonia, Poulos, and Ladd, 1971). meters for this approach are: The required soil para- (1) E u , initial shear stress ratio (f), and the undrained factor of safety for the predictions of the initial settlement, pi; and (2) Skempton's (1954) pore pressure parameter, A, for pore pressure predictions. The second approach, still being developed, employs the finite element program FEECON for estimating the undrained deformations, stresses, and pore pressures throughout the foundation clay. This approach requires hyperbolic undrained stress-strain-strength parameters (including anisotropic effects), and the pore pressure parameter, a(S). Table 8.2 lists the required soil parameters for the finite element program, FEECON. The presentation will include background for the development of these soil parameters and a brief outline of the procedures. 8.5.1 Parameters for Predictions Using Elastic Theory (A) Prediction of Initial Settlement The'relationship for prediction of initial settle- ment (D'Appolonia, Poulos, and Ladd, 1971) at the center of the 339 loaded area is given below. A P. 1 B I v IEq. P Eu(field)SR 8.1 where Aav = applied vertical stress; I = influence B = width factor; of the loaded area; Eu(field) = in situ undrained modulus; SR = correction factor for local yielding initial settlement (Pi) elastic settlement (Pe) The values of SR can be obtained from Fig. 8.7. of: (1) the initial shear stress ratio SR is a function (f) (Fig. 8.6); (2) the applied shear stress ratio, Aq/Aqf, = 1/FS; and (3) the ratio of the depth of the foundation (H) to the width of the loaded area (B). The coefficient, Ip, can be obtained from charts in Poulos and Davis (1974). For the evaluation of Eu(field)' a correction factor needs to be applied to the measured Eu values given in Fig. 8.5 for the following three reasons: (1) The laboratory SHANSEP Eu is generally lower than that from the RECOMPRESSION method, though the difference is small for vertical loading (Chapter 6). The in situ Eu may also be somewhat different from that obtained from the RECOMPRESSION method. (2) situ E Eq. 8.1 requires a single value of E u , while the in varies with loading direction. Though E/S u values from SHANSEP CKoUC tests are only somewhat larger than those from 340 SHANSEP CKoUDSS tests (Fig. 8.5), the larger value of S from CK0 UC tests compared to that from CKoUDSS tests (qf(V)>Thmax) causes a significant increase in E. Eu from CKoUE tests on overconsolidated RECOMPRESSION samples are also higher than those from CKoUC tests (Chapter 6), though the NC value measured using SHANSEP is lower. (3) Although a correction is made for local yielding (Eq. 8.1), an error in computing a straight line to curved theory. Pi still exists because of fitting -e data used in the linear elasticity The values of secant modulus decrease with decreasing factor of safety. The correction factors presented below are from Ladd (1975) based on a case study of am embankment at Northampton, Mass. (Connell et al., 1973). E Factor of Safety u (field) E(field) >2.5 2 - 3 1.25 - 2.5 1.5 - 2.0 <1.25 1.0 - 1.5 The factor of safety is determined from the method recommended in Table 8.1. The following are the five steps used in the eval- uation of Eu(field) 1. Determine the average OCR, average corrected field vane strengths, and the undrained factor of safety. The maximum depth for determining the average OCR and average field vane strength is recommended to be between 1.5 to 2.0 B. 2. Equate the applied stress ratio to the inverse of 341 the factor of safety. 3. Determine E/S u from Fig. 8.5 at the appropriate OCR and Th/Su = 1/FS. 4. Compute an average E(DSS) using the above E/S u value and the average field vane strength. 5. Select the upper and lower estimates of Eu(field) from the correction factors given above and compute Eu(field) from: Eu(field) = correction fac- tor x E(DSS) (B) Prediction of Excess Pore Pressure Pore pressure predictions by hand-calculations are obtained using Skempton's A parameter and Eq. 8.2 (for B = 1.0) given below. Au = A 3 + A(B)(Aa 1 - Aa) for Aq/Aqf < 1.0 The magnitudes of A elasticity. 1 and A 3 Eq. 8.2 are computed from the theory of (See Poulos and Davis (1974) for comprehensive collection of graphs, tables and formulas.) Figure 8.8 pre- sents the recommended A parameter for vertical, inclined and horizontal loading at Aq/Aqf = 0.5 and 1.0 versus OCR. In Fig. 8.8, the recommended A values for NC soil are obtained from SHANSEP CK PSC and CKoUPSE tests since it is be0 0 lieved that the SHANSEP method of consolidation should yield the better value of A than the RECOMPRESSION method. However, for OC samples, since the RECOMPRESSION method yields more realistic values of A than the SHANSEP method (see Chapter 6), OC Af for plane strain loading are estimated from the OC 342 - I RECOMPRESSION data. For both vertical and horizontal loading, OC Af values for plane strain loading were estimated from the value of NESE at qf for RECOMPRESSION CKoUC and CKoUE tests, which are also equal to NESE at (a1/~3)max (the material property), from K values shown in Fig. 5.2, and from the estimated SHANSEP OC qf values in Fig. 5.24. At q/Aqf = 1/2, based on RECOMPRESSION CKoUC and CKoUE sample behavior for both vertical and horizontal loading, OC A values are equal to those from NC soil. Parameters for Finite Element Program FEECON 8.5.2 The finite element program FEECON was developed at MIT for plane strain analyses of stresses and deformations caused by construction of embankments on soft clay foundation. Briefly, FEECON is capable of: 1. Considering initial in situ shear stress; 2. Simulating the accumulation of material (e.g., construction of an embankment, excavation of material, and incremental loading); 3.' Using hyperbolic and bilinear stress-strain models; and Considering anisotropy in qf using elliptical re- 4. lationships (Davis and Christian, 1971) for local yielding. The aniostropic stress-strain behavior and pore pressure response can be taken into account by dividing the finite element grid into three zones: vertical, inclined, and horizontal. In each zone, the soil is assumed to be a piece-wise linear isotropic material. Therefore, three sets of soil parameters for stress343 strain and pore pressure are needed. Table 8.2 lists the required soil parameters for the fiThey are the initial undrained nite element program FEECON. modulus (Gi), the factor relating the actual undrained shear strength (qf) to the strength computed at infinite strain (Rf), a/b ratio, K s and the pore pressure parameter a. The parameters Rf and G i for the hyperbolic stress-strain model are obtained from the relationship given below: For triaxial and plane strain tests: q/ = /(/v t Eq. 8.4 (9f/avc) Aq = 0.5(Aa 1 - Aa 3 ) Aqf = 0.5(Aalf - A = 1 .5 3 f) (axial) for triaxial loading and y = 2 (vertical) for plane strain loading. For direct simple shear tests: T /c h/vc Eq. 8.5 l1/i/7vc)+ RfY (Thmax) Recommended values of Gi/Ovc and Rf are shown in Fig. 8.9 along with the test data used to develop these recommendations. The recommended values of K 5.2 and 8.10, respectively. and qf(V) are shown in Figs. The values of qf for vertical loading and horizontal loading were taken from Fig. 5.24. Values of Ks and b/a ratio versus OCR for plane strain and triaxial 344 qf from CKoUDSS and the loading are presented in Fig. 8.11. measured and estimated qf values from plane strain vertical and horizontal loading were used to determine qf(4 5 ) b/a = ¢qf (V)qf (H) The recommended pore pressure parameter a versus OCR at applied shear stress ratios equal to 0.5 and 1.0 (Fig. 8.12) were determined from Skempton's A parameters (Fig. 8.8) with the equation given below (assuming A 2 = 0.5 (A 1 + A 3 )). aa = (3A - 1.5) 8.6 Eq. 8.6 RECOMMENDED PROCEDURES FOR CHECKING CVVC NSP AND FOR DEVELOPING NORMALIZED SHEAR STRENGTH PARAMETERS FOR OTHER VARVED CLAYS The objective of this section is to recommend suitable testing procedures for checking the design soil parameters of Connecticut Valley varved clays and for developing anisotropic Su parameters used in the design of structures on other varved clay deposits, Section 8.6.1 will present the recommended testing methods for checking CVVC soil parameters. If the NSP presented in Sections 8.2 through 8.5 cannot be used, suitable laboratory testing procedures for developing other design NSP, specifically the anisotropic Su values, are presented in Section 8.6.2. 345 8.6.1 Recommended Method for Checking Soil Parameters The soil parameters presented in Section 8.2 through 8.5 were developed to use in the design of structures on Connecticut Valley varved clays. They are based on test data from Northampton, Amherst, and East Windsor varved clays. Therefore, besides determining the stress history of the site, and the Atterberg limits of the clay, silt and bulk portions for comparison with values given in Table 3.7, the testing program should include the following addition tests: 1. FV tests for indicating spacial variations in strength. The FV data are used for three purposes: (a) to obtain S (FV) for TSA; (b) for use in conjunction with results from oedometer tests to check whether the measured value of normalized FV strength [SU(FV)/ vo] at a given OCR agree with that in Fig. 8.4; and (c) if they agree, to use the relationship in Fig. 8.4 to help for obtaining a better defined stress history profile. 2. SHANSEP CIUC (=0) tests or CKoUC tests and constant volume direct shear or CKoUDSS tests at various OCR's because of the need to check the shear strength in two out of three directions. 8.6.2 Recommended Laboratory Testing Procedure for Developing Normalized Soil Parameters for Other Varved Clay Deposits (A) Non-Cemented Soil Based on the study presented in Chapters 4, 5, and 6, 346 and on the background used for developing the design normalized soil parameters presented in this chapter, the SHANSEP CKoUC CKoUDSS, and CKoUE tests are recommended for developing anisotropic Su . It is believed that for tube samples, the SHANSEP method of consolidation should yield reasonable estimates of the NC and OC in situ qf values, especially when the soil has a low OCR, though it causes the sample to behave in a less brittle and sensitive manner compared to the in situ soil. The use of SHANSEP CKoUC and CK UE tests for the evaluation of Su for plane strain loading will yield conservative values. As a result, an adjustment to convert triaxial S strain Su values is recommended. to plane This can be done by assuming that Su(V)/qf from CKoUC test and Su(H)/qf from CKoUE test ratiosfrom the Connecticut Valley varved clay also hold for other deposits. That is, for a given mode of failure, the design: SU qf (measured from other deposits)x design Su values -or Conn. Valley qf (measured from Conn. Valley deposit) qf values from CKoUC and CKoUE tests for Connecticut Valley varved clays are presented in Fig. 4.14 and Su values for PSC and PSE failure modes for Connecticut Valley varved clays are presented in Fig. 8,4. Thmax from the CKoUDSS test can be used directly as Su value for the DSS mode. Though conventionally used in practice, UUC tests or RECOMPRESSION (avc = Ovo) CIUC tests on samples with different inclinations are not recommended because of disturbance due to separation of varves and the fact that the principal planes are not rotated during shear (i.e., the stress system anisotropy 347 component is not included in the measurement). SHANSEP CIUC tests on smaples with different inclinations are also not recommended partly because they neglect the importance of stres system induced components of anisotropy. qf(H) and qf(45) from these tests are too large compared to those from CKoUPSE and CKoUDSS tests, though qf(V) from CIUC (=0) tests will probably be only slightly lower than that from CKoUPSC tests. (B) Naturally Cemented Soil ) The RECOMPRESSION method of consolidation ( vc = avo vo is recommended with the types of tests similar to those for the non-cemented soil. 348 rn 0 >1W l: _ __ ____~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 4i ¢)) a) M --4 (d 5- -- L44 . o3 a) 0 0 .a , · M X 0) O 0 0. w U 4-4 O rQ)Ot -> a z Cd M z0O 0 LC) 14r U ON H- 0 I I I 0) tm Cl to 0 (a O0 Q) -. Im N 9 p a) a 0 0 -H ., .,- H 4 o3 > cod HCN U -H -H H0. 0 o -H Cd-Hi a O = M V C4r 00. Co C Co 0 04 4 0 4o0 Cd - p ·v to uo rn-4 r oU 5a 0) tlo u) u 0U 11 to 0 VI 0) 00 rc .r _ -td Cd J -> t .-H Eo .- , -,1 a) ,-i O0t a H 4U)CO > fd a) r > U) -H U) -., -H C I U)1 44 4 )0 w En 4 W4J4 E-4 C EtoNI >1 (d -4) '4> -- I C) -r '0) -'0) 4-) EQ M U)> 1 0) 0103 4 0 I. ECJ2I ) 0 E/l 00 ·-H Lo4Cd d O3 0) 4 0 *10) >1 U) a re 04 - -' O M UO 0 0 fl o I0 -H - -- 0 oE 4 4JJ w: k -H * 0 3 LO 0 4 so -H 4 0)W ro0 04 a) Oa Co H C0 II 4o - - 40 4W-H- -0 O) Om 0 OfO i0cn H ad O r oo Pc0)- ~0) HO -) o - 0) - - .0) O - rO -- -H a) 0) 4. (a 04 o4 4J- 0O) 0 O . C Cd 4t90)o I-1 u tO O 0)4 u)o 90) O 0 P; 0 - O 0 W OU z 0U O 0 0)O 00 54 P4 3- rd o U t 0 O M tO 0 0 u - 0O4W00 r HO 0d __ 0) M O4 Ord - PL4 EI- Or 0C 0 0O U P; O w ) U 5-4 O, 4M a to Oo -0o 0) rt 4- 0 .t, rtO 0) t9 :4 (1) rd a) Co tU 0 0O O O, (a ro ra M U) -H 0 -to .rA 0 ___ I H -,H 4 (d E- r J o -H E -, --1 a (aHOa ) a) r H H H H -H H T I d 'U d U - -H M Ci 1-4 UJto3 = 349 Table 8.1 IL · I , I i cn CIII R r-i z0 _, I i o il H o 0 N H oo a) to a) 0' H r4 z U 0 .H Uir- UZ 140 r4 I xU) l U H H E4 0 c4 O 1) (N H ilII 0 ·---- o 0 CQ U) (a CdV - I 0 U C 0 M Un LLP I 0 I .,l p 0 U) H -I >4 a,) En U) 54 m~ 5 0l !l H m- U) Zr m >4 1u- rX,4 o .0Iir IN Ha U W W H H 44 00' Cr 'I; 0 a) Ix Z o 0u & 0r- 00 r-q U o 0 U 0 CN 0 Lc i I (I 1' rd 0z D a,. 4 00 U) a) H a,{ -H co . Cd z En U) 0 U) 44 {O U) .0 a) 0 ,-I -H N - 0 Q) U) r:4 54 0 a) 1- 44 fI: ,r-I0 II1 II 0 R. u U U'. 4-I 04 a~ a) ro 0 O 0 N -- I 0 ,N Cd (d U - V1 0D id 4i r0 U --I II>1 ,-I + 11 O 0 tr (d 0 Ejr 0' U) lb rL -1 O O z 0 I4 0 H 0 Cd 4-) {O ro rd >4 U ,-t II II ll OI0 4I-) 54 a) ,-H t.,i _0 3D H u' U) U E a) -I-i H -H ,-. U) UI -H o 4 a) a) ,c .,q H-I ,. tU .0 um) rl H 4H k i Z co a) H ) -H CD c) a) 4 m a,) i m a) -a).,, k 0 X m >-44) >I (nU)m rO. 01 W4 a ro a) friI: P4 Table 8.2 i 350 SOIL PARAMETERS FOR THE ESTIMATION OF INITIAL SETTLEMENT (D'APPOLONIA ET AL., 1971)-AND FORE PRESSURE Soil Parameter Item u(field) (Fig Initial Settlement: Aav B I p v 85) f (initial shear stress p ratio) versus OCR: E(field)SR SR: (Fig. 8.6) (Fig. 8.7) at i of loaded area Pore Pressure Parameter A Pore Pressure: (B = 1.0) at Aq/Aqf = 0.5 and 1.0 u = Ac 3 + A(al - A (Fig. 8.8) 3 Table 8.3 351 DETERMINATION OF S AT OCR =;1.0 FROM PLANE STRAIN LOADING USING STRAIN COMPATIBILITY METHOD (AFTER LADD, 1975) Avg. Normalized Peak Shear Strength = 1/3 (qf(V)cosf+Thmax+qf(H)cosf) = 1/3 (0.28x0.92+0.16+0.25x0.90) = 1/3(0.258+0.16+0.225) = 0.214 (%) (%) PSC DSS q:(V) cost Th PSE q(H)cosV Avg. % of Avg. Peak Shear Strength 1.0 2 0.248 0.150 0.153 0.184 86 2.0 4 0.235 0.160 0.194 0.196 91 3.0 6 0.221 0.160 0.212 0.198 92 (max) 4.0 8 0.21602 202 .0.16.0 025 0.196 91 From above results. scF Notes: (1) (2) cos SCF Avg. SCF PSC 1 DSS I PSE 0.857 1 1.0 I 0.942 = 0.92 for PSC, and cos = 0.90 for PSE = qcos~ at max % of Avg. Peak Shear Strength qfcos (3) Avg. SCF = 1/3 (SCF(PSC) + SCF(DSS) + (4) 0.935 SCF(PSE)) % of Avg. Peak Shear Strength = 1/3(q(V)cosp + Th + q(H)cos4) Ave. normalized peak shear strength (5) Stress-strain data are presented in Chapter 5. Table 8.4 I 352 AT OCR = 1.0 FROM TRIAXIAL LOADING USING DETERMINATION OF S STRAIN COMPATIBILITY METHOD % q()cos(l1 5.33 8 0.212(2) 0.1662) 0171(2) .18 11.33 17 0.193 0.150 0.189 0.17 %. Th Strength q(H)cos(l) + 94 (max) 92 Avg. normalized peak shear strength = 1/3(qf(V)cosT Thmax = 1/3 + qf(H)cos4) (0.25x0.92+0.16+0.2x0.9) = 0.193 From above results: Avg. SCE (4) A. CKUC 0.922 Notes: (1) I CKUDSS 1.0 I CK^UE - jm 0.864 0.930 cos4 = 0.92 for CK UC and cos4 = 0.90 for CK 0 UE test. (2) Equal to Su (no adjustment for strain rate effect). qcos% at max. % of Avg. Peak Shear Strength (3) -SCF = (4) qfcos 5 Stress-strain data are presented in Chapter 5. Table 8.5 353 DETERMINATION (1)'OF Su BY US;INGSTRAIN COMPATIBILITY METHOD FROM TRIAXIAL LOADING AT OCR = 2 At OCR = 2; avg. normalized peak shear strength = 1/3 (0.40 x 0.90 + 0.28 + 0.38 x 0.90) = 1/3 (0.360 + 0.28 + 0.342) = 0.327 Vertical Inclined E y :5.33 8 142) %h 0.351 · q.V~cs() (·% q(H)cosp 0.280 0.315 0.280(1) o.331 3 ) Avg. Shear Strength 0.315 96 0.318 97 (ax) 8.00 12 0.3423 ( 10.00 15 0.333 0.280 0.342 0.318 97 12.00 18 0.324 0..270 0.342. 0..312 95 Avg SCF = Notes: ) % of Ag. Horizontal 0:342 0.28 1/3 ( 360 + 0.28 0.318 + 0i342) = 0.96 (1) Tabulated stressstrain data from CKoUC, CKoUDSS and CKoUE are presented in Appendix D. (2) cos4 = 0.9 in all cases. (3) Equal to S u (no strain rate adjustment). Table 8.6(a) 354 DETERMINATION (1 ) OF Su BY USING STRAIN COMPATIBILITY METHOD FROM TRIAXIAL LOADING AT OCR = 4 Avg. normalized peak shear strength = 1/3 (0.66x0.9+0.46+0.64x0.9) = 1/3 (0.594 + 0.46 + 0.576) = 0.543 %% 8.00 Vertical Inclined -'2' 2 q (V)h 12 0.594 10.67 16 0.594 12.00 18 0.585 (3 ) Horizontal Notes: (H)cos (2 ) vg. 0.450 0.531 0.460 (3 ) 0.538 0.380 0.576 Avg.SCF = 1/3 (0.594 0.594 + 0.46 + 0.576 of Avg. eak Shear (3 ) Strength 0.525 97 0.537 99 (max) 0.514 95 = 0.991.00 . (1) Tabulated stress strain data from CK UC, CKoUDSS, and CKoUE are presented in Appendix i. (2) cosT = 0.9 in all cases. (3) Equal to S (no strain rate adjustment). Table 8.6(b) 355 DETERMINATION OF S U. ORPSC BY THE AUTHOR'S APPROACH DSS PSE OCR U(H) qfcos (2 ( SSCF S j h )CF COS u S( u 1 0.258 0.86 0.210 0.160 .00.15 0.225 0.940.20 1.05 2 0.423 0.94 0.38 0.2801.0 0.27 0.396 0.950 .36 1.05 4 0.864 1.0 0.4601.00.44 0.648 1.00 .62 1.05 Notes: 0.65 (1) Su = qfcos (2) cos x SCF x 0.95 (strain rate factor) = 0.92 for NC PSC mode and cosl = 0.90 for NC PSE Mode. For OC soil, for both PSC and PSE mode cos = 0.90. Table 8.7 COMPARISON OF S VALUES FROM LADD (1975), AUTHOR AND CORRECTED FIELD VANE STRENGTHS Ladd (1975) OCR S (PSC) (DSS) S(PSE)Avg. P Author Sc orrect Su(DSS)(PSE Avg trengths 1 0.21 0.15 0.20 3.187 0.21C 0.15 0.20 0.187 0.19 2 0.38 0.27 0.34 3.330 0.38 0.27 0.36 0.337 0.34 4 0.65 0.44 0.57 ).555 0.65 0.44 0.62 0.570 0.63 Note: (1) FV versus OCR from Ladd and Foott (1977); see Fig. 8.4. p = 0.85 for OC soil; p = 1.0 for NC soil. Table 8.8 356 I zw Ln -1i J - rI% a- ZGI W z 0 (Z LLJ iO W cn aI W i t.qj K o Z ~s qj I. I Z .Z O0 V) 357 FIGURE 8. 1 m~ sU a-c OCR SU RECOMMENDED avc FOR TOTAL STRESS BY LADD (1975) 358 ANALYSES FIGURE 8.2 zOr Z i t LZ 0"LLJ `O , 10 q h, 1 0) : Z C) CA QC 1 v ?· - 0IJ C) Or C4 0Eo Ld O0 a LL ()n / ( 0L 0O a. 00 C) Ub ,U 'NO1 VA377 359 FIGURE 8.3 Al U.5 I Vria ion of S. I fro7, UUt/C testvo of Ambhers / and Northampton 0.7 i varved c/oy. 0.6 / I / / 0.5 _ Su . /// / I / VC / / 0.3 u -qf from 1kC tests zI 0.2 5/ 0./ /1977), bosad o i I / £fV) fron Lodd ' Foott z Amherst ond Vorthampton data I s~~~~~~~ 3 I I I 4- s 6 I--- I 7 OCR COMPARISON OF NORMALIZED UNDRAINED SHEAR STRENGTH DATA FROM UUV, FV AND THESIS' RECOMMENDED UNDRAINED SHEAR STRENGTH PARAMETERS FOR DESIGN 360 FIGURE 8.4 OCR SHANSEP Eu Su VERSUS OCR FOR CONNECTICUT VALLEY VARVED CLAYS 361 FIGURE 8.5 0. 0.4 0., 0., C - 0. , OCR RECOMMENDED INITIAL STRESS RATIO VS OCR FOR CONNECTICUT VALLEY VARVED CLAYS FOR PLANE STRAIN LOADING 362 FIGURE 8.6 1.0 0.8 0.6 0.4 0.2 In ci O 0.2 0.4 0.6 0.8 z0 0.2 0.4 0.6 0.8 t.O . II k LIU LA -1 k KL I I /.> 0.8 0.6 0.4 0.2 0 -0 APPLIED STRESS RATIO, q/quit SETTLEMENT RATIO VS APPLIED STRESS RATIO FOR STRIP LOAD ON ISOTROPIC HOMOGENEOUS FOUNDATION (From D'Appolonia, Poulos and Ladd, 1971) 363 FIGURE8.7 1 .I(IJ I- 09 04 0 %l i a LJ "IC s~ t 11 -- ~ ooe * -+j00 . *i I, 0 ~~yllgi W t4 li Z I- Z I X QZZ kn 1a %_I-'.-j <L2.. ~!is -~ Z n < > I , + K wo 91 "' 0-(·O+o I .m : I I I T4 *. I ONI..U - - q o I I Ia L-l-r I 1 is a IL I 1 I _,' so _ m II 'A I I a in 4c £ U) c0 IW .I> a-i C,) wo Z W U z fn 0o w i%. v 364 FIGURE 8.8 OCR --- OCR RECOMMENDED UNDRAINED HYPERBOLIC STRESS-STRAIN PARAMETERS FOR USE IN FINITE ELEMENT ANALYSES WITH CONNECTICUT VALLEY VARVED CLAYS 365 FIGURE 8.9 0.8 0.7 0.6 qs(v) -vc as 0.4 0.3 0.2 / 2 3 4 6 OCR RECOMMENDED VERTICAL UNDRAINED STRENGTH FOR USE IN FINITE ELEMENT ANALYSES WITH CONN. VALLEY VARVED CLAYS IN PLANE STRAIN LOADING 366 FIGURE 8. 10 Clta 0.80 _ lk F- - - - C7Uc tests _ _ _ __ I I _ III - I _ - II _ - .~ I.~~~~~0 - . b a 0.7S 0.70 I J.i p. - v. .I2 3 & OCR ', 4 S A 9 1 fH) Ks= ?f (V) OCR RECOMMENDED ELLIPTICAL ANISOTROPIC UNDRAINED STRENGTH PARAMETERS FOR USE IN FINITE ELEMENT ANALYSES WITH CONNECTICUT VALLEY VARVED CLAYS 367 FIGURE 8.11 r | - I (V) z ; ® d i w I Wo-j DO w i II 0 i> LLo rr I O w 0 I ! - i IJ o to rC N 0> v 1vs c vs I O I N vsl I * vs I To 1) I 6 0 I- to '0 W crz Q cr~ CL' '0z a.. oow Nc w WW ~o w c z W/ rvrOL~L ne 0 368 Ww~~~i N FIGURE 8.12 9 SUMMARY AND CONCLUSIONS The objectives of this thesis are: 1. To contribute to a fundamental understanding of the nature of undrained shear strength anisotropy of varved clays; 2. To present best estimates of normalized stressstrain strength parameters for undrained total stress analyses and for predictions of pore pressures and undrained deformations used in the design of structures on Connecticut Valley varved clays, with background information showing how these parameters were developed; and 3. To recommend suitable testing procedures for developing normalized soil parameters for other varved clay deposits. 9.1 THE NATURE OF UNDRAINED SHEAR STRENGTH ANISOTROPY OF VARVED CLAYS The factors that control the anisotropic strength behavior of varved clay are: the inherent anisotropy, which includes anisotropy due to the layered nature of varved clay (material anisotropy) and that due to the prior K o consolidation (structural anisotropy); and when K o is not equal to one, the stress system induced anisotropy. The latter results frox the fact that different increments of shear stress are required to 369 produce failure as the major principal stress varies between the vertical and horizontal directions. The major result of stress system induced anisotropy is a change in the effective stress at failure as ol varies in direction during shear. The anisotropy in qf/avm of normally consolidated (NC) and overconsolidated (OC) varved clays results from anisotropy in the pore pressure response and in the normalized effective stress envelope* (NESE) at qf. As shown in Figure 9.1, due to the material anisotropy component, qf(H) is larger than qf(V) and qf from inclined loading is the smallest. With the addi- tional effects of structure and stress system induced anisotropy, i.e., combined anisotropy, qf(V) is larger than qf(H) while qf from inclined loading is still the smallest. (Note, however, that in Figure 9.1 only the effect of the structural anisotropy component is shown since K o is equal to one). The fact that qf is smallest in inclined loading is partly due to the material anisotropy component the failure envelope for inclined loading being the lowest because failure takes place within a clay layer (Curve D, Fig. 9.2) whereas for vertical and horizontal loading failure takes place across the varves. With combined anisotropy, i.e., total effects of inherent and stress induced anisotropy, qf(H) is slightly lower than qf(V) even though the NESE at qf is much higher for horizontal loading in Fig. 9.2). (Curve A vs. Curve B' The smaller qf(H) compared to qf(V) results from significantly lower effective stresses at failure. The anisotropy in NESE at qf shown in Fig. 9.2 when it is *The plot of q/vm versus 370 Pvm. 370 not equal to that at ( 3)max' is due to both inherent aniso- tropy and to variation in the degree of mobilization of friction and cohesion during shear. Because of the latter, the NESE at qf for vertical loading (Curve than that at (1/ ', Fig. 9.2) is lower 3)max' i.e., Curve A in Fig. 9.2, which holds for both vertical and horizontal loading. The anisotropy in developed pore pressures is the result of anisotropy in the pore pressure parameter A due to inherent anisotropy (see Fig. 7.9) and differences in the magnitude of Aq due to the stress system induced component. The anisotropy in NESE at (a1/a3 )max is found to be due to material anisotropy. Thus, there are three possible values of NESE at ( l/a 1 3 )max for varved clay which depend only on the shearing direction., i.e., across the varves or parallel to the varves. These are: (l) for failure across the varves (Fig. 9.2, Curve A); (2) for failure within a silt layer ( > 240 based on CD direct shear tests); and (3) for failure within a clay layer (Figure 9.2, Curve E), the latter two occurring when shearing is parallel to the varves. Based on several types of strength tests (see Chapter 5), the NESE at (1l/3)max for failure across the varves (Curve A in Fig. 9.2 and Fig. 5.26) and for failure within a clay layer (Curve E in Fig. 9.2 and Fig. 5.31) are considered to be "basic material" properties since they were shown to be independent of: 1. The stress system during consolidation; 2. The stress system during shear; 371 9.2 3. The magnitude of ov; 4. The drainage conditions; and 5. The OCR of the samples. DEVELOPMENT OF NORMALIZED STRESS-STRAIN-STRENGTH PARAMETERS FOR USE IN THE DESIGN OF STRUCTURES ON CONNECTICUT VALLEY VARVED CLAYS Best estimates of normalized stress-strain-strength para- meters for use in the design of structures on Connecticut Valley varved clays, and recommended testing methods for checking these design parameters, were presented in Chapter 8. The back- ground for developing the normalized soil parameters for Connecticut Valley varved clays is as follows: 1. Anisotropic S u parameters for plane strain loading-Tff at the qf condition from SHANSEP Ko consolidated plane strain compression, direct simple shear, and plane strain extension (CKoUPSC, CKoUDSS, CKoUPSE) tests corrected for strain compatibility (Section 8.2.2 are recommended as design values (Fig. 9.3) for Morgenstern and Price undrained total stress analyses. The reasons for considering these values to be best estimates are: a. K o consolidated plane strain and direct simple shear tests simulate representative in situ modes of fialure, i.e., the PSC, DSS, and PSE elements shown in Fig. 9.3. b. Values of qf/vc from several types of SHANSEP 372 strength tests (e.g., CKoUC, CKoUDSS, and CKoUE tests) have been shown to be the same for three locations (Amherst, Northampton, and East Windsor) within the Connecticut Valley (e.g., Fig. 4.14). c. On the basis of CKoU triaxial data on block samples, the SHANSEP method of consolidation is thought to yield reasonable estimates of NC and OC in situ qf values, especially at low OCR, though it causes more heavily OC samples to behave in a less brittle and sensitive manner compared to the in situ soil (see Fig. 9.4 and 6.5). Note that in Fig. 6.5 the lower qf value from the RECOMPRESSION* CKoUE OC (OCR=4 the in situ OCR) sample compared to that from the SHANSEP sample probably results mainly from disturbance due to separation of varves, though when lf acts perpendicular to the varves or when the effect of disturbance due to separation of varves is small, it is thought that OC RE- COMPRESSION data on block samples give the best indication of the in situ soil behavior. d. In order to reflect the in situ behavior, and since the effective stress rather than total *RECOMPRESSION--the method of consolidation whereby the sample is consolidated of the desired OCR with the vertical consolidation stress that is less than the in situ maximum past pressure. 373 stresses control the soil strength behavior, the undrained shear strength is defined as Tff rather than qf. NOTE: In Fig. 9.3, the Su values for NC ver- tical and horizontal loading are based on plane strain ccmpression(PSC) and plane strain extension (PSE) tests. However, the variation in strength with OCR was obtained from trends measured in triaxial compression and extension test (see 2. Fig. 5.23 and Section 8.2.3). The recommended values of pre-failure pore pressure parameter A (Fig. 8.8) were based upon SHANSEP plane strain loading tests for NC soil (since they are believed to yield better results than RECOMPRESSION tests) and on estimated RECOMPRESSION tests data for OC soil since RECOMPRESSION tests on block samples are thought to yield realistic pre-failure stress-strain pore pressure behavior for overconsolidated deposits (Figs. 9.4 and 6.5). The other recommended normalized soil parameters plotted versus OCR are Eu/Su (Fig. 8.5), the initial shear stress ratio, f, (Fig. 8.6) and hyperbolic-.stres-strain parameters (Gi and Rf (Fig. 8.9). 9.3 RECOMMENDED TESTING PROCEDURES FOR DEVELOPING NORMALIZED SOIL PARAMETERS FOR OTHER VARVED CLAY DEPOSITS For undrained total stress stability analyses, SHANSEP Ko 374 consolidated undrained triaxial compression, direct simple shear and triaxial extension (CKoUC, CKoUDSS and CKoUE) tests were recommended for obtaining anisotropic plane strain S u values, with an adjustment to converttriaxial Su to plane strain S u values. (Note that use of triaxial tests will lead to lower strength thus yielding somewhat conservative results for field situations involving plane strain loading (see Section 8.3.3)). The adjustment can be done by assuming that the ratios Su(V)/qf from CKoUC tests and Su(H)/qf from CKoUE tests for the Connecticut Valley varved clay also hold for other deposits. for a given mode of failure That is, (PSC or PSE), the design: triaxialq measured for other depsit)x design value for Conn. Valley triaxial qf (measured frm Cnn. Valley deposit) %7- Su values for PSC and PSE failure modes for Connecticut Valley varved clays are presented in Fig. 9.3. qf values from CKoUC and CKoUE tests on Connecticut Valley varved clays are presented in Fig. 4.14. Thmax from the CKoUDSS test can be used directly as S u value for DSS mode. Due to distrubance from structural damage, especially due to separation of varves, UUC tests and RECOMPRESSION CIUC tests on samples with different inclinations are not recommended (see Chapter 6). SHANSEP CIUC tests on samples with different in- clinations are not recommended because they yield unconservative qf values for plane strain horizontal and inclined loadings (see Chapter 5). In cases where predictions of pore pressures and deformations 375 are important, in OC deposits, RECOMPRESSION CK0 UC, CKoUDSS and CKoUE tests are recommended, rather than the SHANSEP method if the samples are of good quality. 376 I l.. qf ('3) 0.4 0., o. /O° Angle Between crf MATERIAL ' YerticO/ DiectIn) AND COMBINED ANISOTROPY CONNECTICUT VALLEY VARVED 377 CLAYS IN qf OF AT OCR = 4 ,rr- ^sI rI'-lUrt .I r,,, E z cr w z z z z0o- Cr Zr c] 0 mlm z 0 w Z: cX m N li c( b N'- 378 FIGURE 9.2 0. 0. a. o. S(4 &.vc 0. 0. V./ RECOMMENDED 3 OCR 4. 5 6 7 8 9 ANISOTROPIC UNDRAINED STRENGTH PARAMETERS FOR USE IN TOTAL STRESS MORGENSTERNPRICE STABILITY ANALYSES WITH CONNECTICUT VALLEY VARVED CLAYS 379 FIGURE 9.3 .j CK o 1C test (t5 ) - 0.7- --- --- RECOMPRESSON SHANSEP . 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C-) a I ILJ gCZ0 0 0On Z < _ 0z I 0 N a > I W I.U) ii 4 a: '- 0 I: Ib- U) a. 0 p W L*J o 4 u, Q q I I jj) .f I W 0, IC/) R1 I W U1) I- z 05 'm Z U) Lii a: I.z0 U, z 'r 0. 0 W x 0 Li- 0 Li I 0 I W a: W S c 4 IC I 4 a 4 4 bal 4 4 la '6 I< ir Z hi Pi U' d !ri10 0 01I I a. I 4 el 4I t Iq 9t a: 0 _A 4 U) hi 4 _ O mg Oj IrU) S. 06 . 4 o a U. 4 ta Itn 0 U) A t) *-I j dr 0 43 4 06 IU Iii It v a ~1 a: 0.6 4 0la %4 w1 IV 14 J It. - '4 c 16 0 Z ~ - 0z a: 9 'm .f 0 0 o~ C '4 IIo It0 es (.% 6 ~_ XI ("4 C, I J W_- 0 A #4 0 .0l .I O ' P. sa T1 t4I C; 06 C ,1 6 0 z I C4 2_4 T 0: i f, .0 I4 t'o f6 ,4 U a. CO U) - U o 6 #1 IC. 'U 0 1- Wl a1' a o 0 ES 10 ,0 _L 3 4C 4'a 4 WC.) 0 L t4 1 C4 I I i 4-4 . _ I 0'5 0 0 C 0d . F 0 .il 0 Ct Z W) 7 a 4 4d tL -J I-0 C 0 cc a a z a d 6 Id 6 . CD t0 II 0 I 4 i 0 I. .. Ed i #4 i L- a o0 I i i aU I' I4 q. frI 1t1 I-t i 4 a i .t- 41 0 at a: I 1 I4 0> -2 U) 0 0 I- X, < I C.' cr K IU) W I 0 C, () hi -j l 4 a: a UWW - a: 0 Li 0 (A V3 al 0 Z <) . _. q A ... _ 474 4 ui~~~~h 0 0) o 0 LU hii aI hi zj En , 0_ Z0 _. tu .0 J 1Z o -. b-: eZ 9L >w: 4~~J ? 0 ~~~~~~I-J Uw it 0 - 0 0 w o I: X z o U x hi I o. 0o W W W crz #A :t 0 pL an L9IW 4. zIJ 4 a4 4 4 zn W I I iI 0 0 - 0 4 d o0 ¢ ,,t a A ,°, ahi 0 hi U w a. £t A; a 0o _ I 4 _y SECTION D.2-1 TABULATION OF TEST DATA FROM CKoUC AND CKoUE TESTS ON NC AND OC SHANSEP EAST WINDSOR SAMPLES 476 I U! w tr I- 4 w z W 0 to 2 . I(n 7 0uj-j SQ I 0 1 I- 0-J 0 z z w I L wT . 0 tiJo I :< co W r ::) Of £° .w .J _ -; .(" E R 4 E .1 a z .0 Lu 0 z 0IL Z -J I U,k S _. 0) w u; 03 1-a:I w 0 ) t- -i CI) ax z VI ui 4 U,V 4f) I.. o¢- o0 w 0n a o I.- cr a: 0 z )I0 Z >: ::) §r 0 C i ! (U) 0 4 I.- U) IU ao V .A I w _J U) z U) 0 bJ 4 ,qc o iI4 wIIs w _ v 4 IL I (A 4 .. 44 4 4 w I;, ( aI E U x ow - - 2 O U 0 lo m 4 k3 - 00 ).1 ^ , j Us C Qo _ .) m .1 I a 0 ¥o fZ ~o I -J I.x 00 0 o-A o or U <q lx 4 a. 0 _ILI -) T~~~(O U) U) h o t n x 4 E Ct 2 I- h; i-h O zw -u U.J 0 _ I- 'I 9 aZ > ,I 2a: -W a- CF -9I le it _J IC IZ jt -A _ -1 A t4 .Ak t - C jjI Uc I Cm S U) hi lxr J.Li 0 L Z;o4 4) 0 U IQ *L h 0... zn I U) w U) CL I- lx V) a: CW o i o L 0 I i1O AE 41; 1 #.III4 tI tZ Ux - U)).. r o ,,o 0 * m v oHIs 4 U) lx a: a n* 'a9 12 U) CII o0 '4, 0~ GE 0 UL b a: O4 0 Jul F J o, hi r I- U) C. Z , )0 hi "Ifr. to U) - in 1U) _ 0 U IL 4 478 4" j w I4Un T 0Q0o I'S 1* w Tn 0 : o w a -J I-J 0 (K r ., IEQ U c1 Z S O I . I I j a r ,, Z 0') - - - - I-- U. 0 fl w OJ LU -r 0 f 0~ U l- - ~ a: lb v H 0 F CL 0 1 (w .. i Li 4 Ir -I > 0 (/) I0 4 F, - - -hJ 0 I- Z 4 I 0 a: a * a: J c) CO Z O2 I J U) z Ias: I F C 0U - | 0 _ I 0 IZ,; V)J 1Iz 0- F0 ag 0z I 0 0 LAJ i U)I0 ax 41 :00GO4 4-J O v U, aa a: I. LU w I W " CL o~~~~ 4 0 S ; Z LU, I -i I w 0 4 1 4 | 44 I. cI P) I 4 4 1 1 41-4 1. z I 0010 - 4. t'~~~ r474 11 0 ! , o 0 II #1u 24 f.U, I"I r ,.i .-e w CT 'Co 0 Z ~ V~~~M Z 1 1Q I~~~ * ir 0 i ~l o t I(Ai 0Z2 I 0 tL 0 b 4 w )0 LU 0 0 4t a: tL LU ) ffi a: ar : 1 0 w 1- o 4 4 _ 4 _ ,,4ZII En En I - 8 ItX la Er -C I i En 0 ;a 0 'N 0a I- I :A W 0 i.. 0 i|Xo %Ie 0- a' 0 A, o 0 W Z r h a 1] 04 I In Z U) Q 4 u I a: . C<I. W~ 6 z a: WU 1 'I ri 4 .'t I xZ 9. W En 10, U) Z X). "lb - ... i~r 1-~ !- -4o W I 'V qW - ,9 En I0 Le ac E n' C] En ti 4 -.1 O cn w o1-4I In 0 ,i-j )~ 0 ,0 I- 0 En 44 le I I oho:,"1£n o I 0< I-I II V) vtiII 4hi '-r- -I W o -~~~~J En hi I- L' Clg -qa4 - I L l *er 0 0 ZE cc I41 - r. 41 loyp .I Vs ~~Q ~IA ve * lb -4,' L)I 01 4, Cl l E I - 0 u or 0* '4 0 W, l 0 2 I--0 I- 23 4 AU U) I 0 0 I-- 0 w I. v) Wi co En Er I-En -j -J x lb r4P~U~ F 10~~~~~~~~~~~~~~~~~~~~ 4O rN r.£ hi IU is~~~~~~~~~~~~ Icc n 0 ¢ o Ir a-. C) I.- Z 0 2i '0. W IE I1E IJt 01 C-- E - 0 P4r-I 480 - O,.. , 0 O4 _0 - -7 l - V I ur:n 66 lIl U: O a: 4 a 0 C 6 '' 666 0 0 6 t 6 -.- Ii la 04 O 0 0'~ 6d 6o C -~ 4i0 0 J t0 006Q icOO- 6 q T IIn '4 ' . . ~.. - N 0 M CD a, 1~ aoI F C 6 I I Z 0 40 o 0 Li 6 i Ia, -,z 08 a d566 a a ww Ii T: ~6 t 0- - [!oo3 al f 6~~ ri- 1 Z ) ,, 'I, UJ I 4- a: a. ., w1 X 0 W Q cSo N o cn 6'4 t w - < C C '4 uIC 16 rC C 1 i It t W d C e E z IQ (A I .1 Z J: C (0 Id 00 lb O W I-Z V) IC tl: C WL k~6 0 0Ccr :$ d0 U. -- O0 0 'a. P\4 N lx : sZ V) 0 (n 'IC %~~~I '3 V 4 W DbnD U.) 66a :6,6 60 06 . 6 Vn 14, 7,'C 56CtA. 16 0 ~0 did t A 'a I ' P b0 cc 11°~ t fr VI C! lb, 0 0 -- X o C C 00 0 0 01 1 6 %!.6 a1 6Z Ws i (A a: zIn U O w XI 0 Ii _ c0 ae § .z .b 00 7In in C O o m ) U) ] C a i- 0 In In I' a zIL I- J: ) In a:w -I Z- Z 4 Itl 4 Vx w al: . O W/. cr IL a. .' a: 0 C C #<) I, tJ w I _ 0 i i N r 6 1*tL- IC^ 1,? C a: cc I4*~ 0 Z U. 1* 11 . ¢C 4 w Cl) O V) tD-W W.- Cow U a Er S C 3 $ I - 0 I T< _ _ ,- a: 0 I-4-, ZI 1 I O Q 41 44 ~1I IC 's .A V~ ? 4II I 4I 4 I or O- 4 -.I 'r, ,I 4 :i_ .I -- - - 4 rS a q0 0 U - . iV t i , i I~I ->; U - ,1 W lb O 'T 3') t 010 t '~ofitIF 6 .. C C .Ai i i I~ _ 00 91° Oi- ;7 t- 6:6 o~ l'- 0Z o ; i! i ~, r '1 In w - < a,: o, -. I i I KW *. .. _ _ , , t I ! -' %_ . ... W I I % i-i --- ff)lN I A'fS '; 1 ! WI'- I-1I L llLL i S! tfl t1 ' ' - ]- I _ I L_ I - I I ! I I I alo W o 0 O I o U- J 4 id 040 0 Z 0) hi '- 4I>.0 0: w - rn 2 w 2U 4n &- 2 w w z U 0 I.- Z 0 z0 04 Wl z w CE) 0 X I-w h 0 aIL w I., e a 0alw o I - 0 L 2 x 44 4 4 4 by4 4 z_i 0hI o co IU i"b1~ 02 o ':: 0 p u q. 2 I .- 0W hi hi C- Oh4 aI.M0 wIL) oa UD 482 i or 1I-fn IA ' 0 11 4 4 ~~~~~d __i_ a c _ acO _____ ______1 0 "a 4 0 2 I- _0 c0000 5 C_ la% 0 a i 6 ! 41 4 0 ,U i 1cAt~~~~~~ ~ ~~~~~r4~~~~~~~~~~O I 60 'U IL 0 t i el0 A! 11 1 . 0 ¼: ' 9' qa aX 0 h I , , , V1 1 - 4 ~~ ~~~~~~~~r cr~ Co. 0S 0 Z 1 W | A C) -J c Ifl a. OL 9 4 JlU 19 a -o I )0 I- hi at -J I hiC I-- :1 ,F ;,W - ' 'sagI I:0 I tW - I ~ ¢N ~ 0l50 O >50 14 (5: e I1 I 1f05 U.t ,tz 24 0 x Ci w 0 h I2 0 Z) -j T! I . 0 ' . 5O I~~~ 40 i ti '4 ' ~~~' 1<l2 eciO6~~~~~~~ fI __I r 0; -- [S 14IV ^< Ort<5^l 0 O 4 0D 2 z , 1 In t 0 w M 40 a. 2 U 9hi o U. U# 2 0 44 4 4 4 4 4 I iq 1tI II ri MI :a A 4ja z2 I10 I- 0I 0 or 0 C tL z CIt 0 t-* I ! e 4 0 r0 I a 0i 1-U . 0 U 483 I 4 0 11 4 I '46 6 6 6~00'O6)o6 6 I a 2.h 0 2-4 10 4; w It 02 IC u a 0 cI 0-S 66 I I-. 66 66 C 6 6 , 99?9'~34, w, oc IwI0 I8 : ) I I IX . 06: 0I "I 81 FE81 1c1Jr u eI 0S fii 4 0 1Il lS2 lb- br 6 O'- 6,6o66 1414~~~~ t?stt~~~~01 w I-- 0 o~~~~~~~t o 4,. 20 0(0 L. 2 o o Za S O.. 40 _ 0 ~~~ ~ ~ ~ A t 4 0 - c .i . -0 4 4 ~ 4 o .oW1 JlL 0 4 4 Z L) ?, 4n0 : 66666 - .....oo 4-'4 { -= = I.. el) 4 . . a CA 1s1 Ag N . 0 - 1a W01 , 4I~~~~~~~ ; 0 0 IUo N gul I- w c. 10, o :e 9'b aWU- .-J v 2 I I. O V 4p. U 4 a i 484 SECTION D.2-3 TABULATION OF TEST DATA FROM CK UC, CIUC AND CK UE 0 0 TESTS ON RECOMPRESSION EAST WINDSOR SAMPLES 485 Ii .U) .! w 49 W I U) C, .z a, 5 I -C I-t In 'I- a $m r Ul t 1i - t 1 r ~e~ir j o0 1 66an o6o6o S0 E r4e II n, I If l 600 !J 4)'-o >_ I%: t 066 ,, r ':.. - 66~0 -I-6- 6 C-) F 2 Z :6 a 666 . ,; b- 6o660 6 W X 0 1) ) i; E z In 0; z E zZ - t 0 Z cr - CC 10 II lb v C - 0 d VI -- I- co~~~~~o o U) ~-~,~ o606 , 0"~~~ II ak o - -I . I. 2 U) a. C) I J at 1 6 U) hi Ir a. 2o tr w I- Ia w ) 0 I 4 I. . -9 1 o6 0O(a C ; O6Qa. l 1v .1 0co I.- s 0o o 0I -7 U) ). U) U) a I- o U) C 0 In 2 cn x' , all CA II 0 1 z -l w 41 tl hi@ .. * 1C a I I o V I - 4 44 4 hi Il 4J - z 0 I - 4 0 a 0 I.1- - o ) z - qCO 0' 0- ~'0_ 6 ,~ 4~~~~ U) Z °i I cn v, L I- a o 0 4 2 a 4v- It x In . hi I.- 49 = 486 ¢ 4 U I. 4 V U' U IF 1 !; I a: 4 0 L laJa: I- -C 0. G U) IS_ U) I-a: K a a-Jw .0E 0 0 0 l'0 U O 0 I -4- aa: a. 0 wo Uu .ito 0 cr 00G ~r., . ..- W aU) - lZ*: a: 0 i.--- I U) a- '4: I- Ib b'W 0 o %O b U b) aw 8 1 - U) 00. a~~056 - °~z I- aL IE cc a w a: I 1' U) 2 w E I1 -J w Iw 0 I zo ( z; I- I U) 0 I) a z ,- z ii 0xI.- aLw U) o(1 o I U) ie '.... U) cc Z O32 U) p CI3- I 0 on w I- U In V) a-: gt0 C t 0 lAJ - t b a. w 4 4404 a. 0 4' O (fl -566o'~56 ~ ~ ~~~~~ .01- o- oo ~'; 5 I . IV I P: 9 0 e (hi 1- H e d z 1--W t c -J2 Lu _ "a lb, -I-....... H Ž-~~~~~~~~~~~~C -- ~~~~~~~~~~~~~~~--~~I.__ a: o 0U. G )m 1uI 01 aU) Iw (n U) U) w w a: W a a b 4 O U) om 0 ~~~~~~ 4 4 4 487 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~J I-l U or cr a: a: ~ o,r C.. 0o 4 o ~ = *.D ==' o In n l U) 1 hi 1- Io z 'C Q, a 0, R w 4 W r i ' nI I-- 4C 0 Q .O~3GOOOO 0i W z 0 0 In 0 -JI -J 0 I 0 U, a L 1i 6 6 66,66 RIi 0 ...... o Oa 0 * 1C N .9 Mi 3t ~~~~~~~~~~~~~~~~~~~~~. oo oo o c5'6O6O0,6 %% 0 '4 U 1 ~ ~ 0 0 -~ .1 Vz U)' W IL lb R1' bt ., 40Z> 0 4 E 4 a, - 0a q (4% -~.:. -, VI -, 1 0 U) - - 0 14' 0 ~~~~~~~~Z1 - z0 I U CL I U) w F Z . - U 9- I-. 9. o o- E~~~~~ii 49 E Z 4 to' W~ X ,t, 0) I I ; U) Ii In L cr o 4 -i z 44 _~~~~~-I.~_ I '1 CO q IVI or ( 0 IL 4 4 414 - q----- - 4 4 44 13(l C AtA -a- .W %, I -4 0 I 1-; W V11 r 0~ UP Ib ~~ ec o 0 % 60 0 -;s ~ ~ ~ ~ --- -- 4 4 o c , or oO06c50V 0488 ' 0 U. _ 4 1., i i ., or o en To il ki 0.( 2 w 14. . _ '4. 00 N~ ~ Ia 0. t U) 2o U U. 3i I- a) I0 U) 0 UU z - o 0 W W a. > C; IAI 2 0 wI- VI a | >- 0U hi1 W V) I or U w 0 I, o 4 C) 0 Wr a. - 4 I7 0C'I 0 I w aF- 0 20 mNO C4' j in N -91 0 0 i Sw 01 0 a o \1 O 0 w I, 7 I c ~0 60 41-91*1^A1 W :0 _m Tr-r-TFl . I 0 0 ( 7 11 I.S I io .E(( ooo60 'A a sr LAi <1- 0 4 '0 0'- !fl I at I ao 1 1 ', 10. o^ I t I'- _ _, cI IC 4 0' . L- IC, Ill 1b - <.. -Ia I 3 I : I.w 1 IClb o I. 1¢' 0 _ _ O ~1 1S I I & "ItH-tett~- 0 I I -r -It IU) m 4 wr iua E in 14 1-6 E -a II Ii E I - Lt 0 0 C , 4, 1b I. -4 a- _ 0 0 o o oj ao S I1 U1) FW -A. tA; z> I - ui z 0 IU) - lb 0 a a! 0 I z a- I Ir 0U 0 C w -I I2f 0 w o )( - O I Vr U) z aI <) 'I C o) t I I- - I, I (j) 0 X r I z- W 0 II') I It) IW a a. In w . 4 I;z t0 I.- a. (0 Pa lbt C 0- lb 4 I iI C lb: 0. 4 | rd f' | 1 i |l I I 6o r-- C) IC t - F t's I jI I- ' U) I 10 LU -J (r a. Z < - 4 a] It (0 I 0 U I 41 j CD 0 I- tI C) I.0) U W ; C !ti In lw cr - w J Z 6 o Tttn~ i I t t. I IS O r -J Li i- C ,IuC'uit5~if -: ,L'--I I U) 00 I.. 4 0 I 1 0i i - iSYw a. 11 o IF i 1 / NI LI _-E:-L i -Lfi 489 I Ioa o () > U) I fn 6o 666 o v I0 I L; CE 4 Ii 4 0 ~~~~~r J 1 fn I- W tA A)66 6o6 66 6~ -66 14,1 .i Ct 0 CE h. Cv cr I.U) IC .5 ar - *o~)o [i ;o .i ,.t .,="'t r 00 -J -0 I 4 E Z L 0 A (A C' r .. coc L 0 '0 C 0 'IN cr 6 0 I U) (nl i a:~ o I C-, 6; 6 1.C *r cn .j ~... _ ...... _..._ _.,.... 6~~~~~~6 1-p ~-3 w z Cr U) I- E 66 i0 z E -J r4 0 F U) -~ I tu 0 Z QO IfI ap C/; 0 Lt 0 0 ,... ~ , ·~',~ 00 go~~o~ o"," -.fo g6o 0~00 ~~ U) I 1- - o1,,6 0oo c0 lb U) a12 otto. N~~ 4 J oU 9L cr t La I1 iU) I-. 04 zr 0 In U. ILa U) 0 (n toF 0wVK W 2 (L W X LaZ w x 0 0.J h4 O~ ~~~~~~~~~~~~ IILa . j --iO--- --- ~66 *o U) Ir Z I ~ U) I- 4 < Cr -'rb ,4 U) a,I tn 0 -Z I ' -Z .. w lb"'' 14 7i v 'o~~~~~~~~~~~~C P49074 o 4 U 1. 'C V< 0fl -I 0 0 I c*J 4, 1r vI ef a :i I- 0 z Z I-. (A La l- -C I tu 2 0 Or) aa to U) i II )-1 0 L U) F. La ,I La w sU) - 0a I-La U r 1. 'r ,?, ° I I I I 40 ,d th -J 4 e ^2 J0 C0 0 w cr or 4 I'° I 7 1 IL 5 6 0 0 0 C" E I:, rN I 2 4 I- -o s S. 0 "A 0 rQT 0 -0 0 z 0 0 -j 0 i 0 0 ie Ir Q- ox Tr W Co 0 I-- C- ¢5 0 0 1; rl " a A-- ac .j 0I O K.. O ~4 0 _ '3 CC% I-C;6 - v 2 lb C-' NC El z E c- '-9 2- 0 o-o 00 R 6 0 0. _D ti a0 W CD J I.-' -0 CI 0< GI: m oJ LJ - 0 IC:U) aU;: I (0 r C- x) -D 4 2 OI I? 2 r- '-I VA -t k I I I 04 0 0 I- 6 0 4 C- 0 Cc' z V V 0 U) W Iot 0. 0 V 'SW o0 ) o0 C) C IA 0 tCW) tn 14 0 -J Z 0 < z W 0 U) r. = 0 - 0 IIA _ '3 C -o -. , 0 4 4 4 1Sr ._ 0 0 14 rU C-S g I" 4- 4 4 - c4 _D C) 0 0. W 0 Ix U) 0 -9 -Ss 0 U) z W 0 -I (A - U) I-W) I- V K- ;4 I0 -.4 U) W W: U) w '9 0 i S. _6 Ix c- - U IA I-' 6 0oWV z Z r- .-O4) 1-4I'S a -. 0 I <:r '9 .s~0 -9 . O-N C 0 < 0 I I- 0 0 0 1A4 lU 49 v, w < 0't -o ,-. '4-J 0,4 0 '4 2 en 0 6 I) I.- V 0 D W r-- cf-I 00 W o6-_ .4 0 0 I 0 0 Cr. C" IF - .C- U) III . 4 6 2. U) 60 V 6 '3 .9 :1 17-'-I 6 00 I '3 0 - 0I .-9 C r I 0 W g 0 o 0 4 IC@ w r- r- I.- -0 6 '4% 0 4 4x 4 Ig 0 C" -i 0 N: 4 ' -S 0 0- 0- Q 3 0 O -a 43: ' -IS 1 I1 i{§i .'rt R C 0 o 1 0 0 I 0 -9 a W ( C- In . 0 U.1 C I lo1- I~ -I- U) zn 13 L4 l'U, ni 4 I(t UP Wi -. 4 0 0 Z CL O li, Q` 1| 1 0 0 W WS, W - - - - - . . ,_ 491 J3 '4 I II a i :z co U) W cc I Q U1) w -a ~.~.l 0 z Q )I o 0o -jh 44 I- z . a:) C 0 (O zr_ IV) U) U) cc -_ KI4J _ ,-' ~5 w~ L2 a -U) ~Z tr 2 I E UA) is0 -J > E -j a t . _ IZ Z 0-- 0 t;a I 2-(r > A 0P 0t u W-- C-leIL) I co; Z o~ w a: V) U)o 'A) u 0. 0 X U) C) W >- o Ir0 o U) U) co 2IA) I- )( o IA)r 4J o-j -Ii U) z C1) 4 4 U) z at a. 4 , Iir I. 4 i, 4 Iw U) g Al 4 4 W 0 o0 c I UU ir 0 . zA Fb 8 13 °t 0 . C 4 n X U 7P, cr I r 0 492 :1 4 SECTION D.2-4 TABULATION OF TEST DATA FROM CKoUDSS TESTS ON VERTICAL EAST WINDSOR SAMPLES 493 Sheet I of 2 SHEAR TEST DIRECT - SIMPLE o i4 2 Pp(3.iFCT , . .__ __ . SOIL TYPE URf)~u C4y TESTED LOCATION es'r BY 3NL .ivm 4.a/3 oc Preshear e i I I i 0_ o Rate (C/o/ Hr.) o366 0 o o.ol I 2 LL0 0o244 . 131L. o,_q o.178 (T _vc _vc !.ooo o35 .o. h hREMARKS m V L 'vc L O.aq. o.z29 cDy Controlled Strain //" Stress 0.660 T rh fl I-ao 448 O.q7 0.026 O.q74- G-O57 0,q4'3 .51 a 74 .a17& a. 067 0.6q o k 036L0 6.e-o4 _ O._ __6q 0.683Z Q.q33 o.ql 0.o87 1 o. o o. I 2 e. t(.a O, n.qs' 89% O.044 / .o 0 o. o.ao OZ.4 vm o la_ .6 a-, ,_ j. 0.1Qi,4 14. tn.r a.18 2. /5Z0 2.5. .2! o.14 2.56 _ a. IS4 3.433 3.8q 4.34q 4.Z1 .8 ,q 0,16 n-a ~.fS O .l&Z o o.4 ~3.~8o .1 0. .Z42,, A•34 0.($1S& 62ss s46 a3.~41 C. .&77.2. oQ.i:q: O.q8 824,41 Q 6.f7ql S &5"qoI MECHANICS LA BORATORY DEPT. OF CIVIL MASSACHUSETTS ENGINEERING SOIL INSTITUTE . _ _ _ a.2zl 0 ,_ 4 o24 t o.0. '/.'18z o.-,,f o z . 0.71 -o-c8 G~l~l0.~44 (40 o.fz O .72g 0.11i Z2. _ _ 1_ .161 0.751 o 1 l0L o.II qZ. 0.22sI O. a Zq a . olt -.aS S o. O $.2g ' l _ 7,4z O DURING SHEAR O1112. STRAIN () .0.014 azs, . I Final TIME (Hr.) )_ X( 41) S % Hay ~~ ) H ( S,% . .0-I Initial 4 a13 tc(Day v ) c(%)/o) tc(Day ) - ) ° Vhc . DATE DEVICE CONSOLIDATION (Stresses in /,vojnP OCR NO. EDS-i PSS OF TEST TYPE _ __ °_ o .M __ _ __ _5_. -__s I REMARKS: OF TECHNOLOGY 494 _, . Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE PROJECT 8012 TIME (Hr.) STRAIN Au (%) q.5s8r vc o0.(2. o..- I. 0.14 a 4.48 II. 5,1 o. 11 vc QW4zL alSu o.11 (87 a 10o 51 13.5'r cls'8 , 0.53( . 0. 24 .. Q 648 0.464 ffi 4eS oI33,2. _ o.341 al.&ro O. ,I s bF1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. . SOIL DEPT. REMARKS vm .30l 0.1 .3a la,.T./4 (.5I'Ss , $$' s ~ ~ , 1'7. 1, .15 , SSSolf 43 bsas rh 7vm 0.3o 6.5Z a. 12.· s' 17. 141 b. lSO rh 7v v c a.3o NO. ED:-I ': TYPE OF TEST 15S SOIL EAST -'ciPW LABORATORY MECHANICS OF CIVIL ENGINEERING MASSACHUSETTS INSTITUTE REMARKS: OF TECHNOLOGY 495 Sheet I of 2 DIRECT - SIMPLE 814.2. PROJECT .,v~ TYPE SOIL TYPE VARV/D SHEAR TEST OF TEST TESTED NO. £D5-2 .'3)L. BY OCR DEVICE DATE C4A V LOCATION _dsr CONSOLIDATION (Stresses LL//p.Ro 7 vc 2o () lH H( tc(Day) W,*/, I - . . l Initial e - 1 S,% i 26 Th fcr,,) Rate i I . v O'vc c zvc o o./ , Th (%) (Hr.) o O.azZ o, M 44 /I. Q.0185 . -. o.o .o a. o L OSG 7/ -o. Goa . 7 o. O26&-.os, a. asa _7/ O.Z 1 no'/27 .. O.1083 -.. o.t?4 2. 1Z o310 140. AO. SHEAR ' Stress .195 ' Hr.) (I/*/ R E MARKS _h Ovm m f.4 6I,# O. 7/ aooo a.2S& G0047 . 2L(7t O . 4 a-di . 6" I, £&C4I 1.,04Q o. a 5S6 o.0i148 a.t2L&q _ _ 1.6q-o GO&S& a.ofi~ 1 Lf, 1 6 .1- 0 O.,I(.i9 I;GT - , 67 -. Ose e667.. .1 a O 11L7& ll L i. OAt o.,!sol' 6.aGIq .7' A1 63qq __t''1 6. .~q6 O.2Ug 65O 1.0.88 ____7 .6__ .26f3 I 835 . 2iz9 I.4 If 3' 1.77 . 236 -O. IS? _. .I 3.54 .q~ o4.S'-O. lq o.971 ~.T SOIL MECHANICS DEPT. OF CIVIL MASSACHUSETTS 8 a.0(&I 1.128 O51. 067Z7 .!4l 13405 i5 .4qq 0.$3( -o.IfZ .168 o.77 0.l78 .2 (_ _4z a73 o.ao - OJ 1 . 1 Q t71O _ zS a2S IL28q - 0.271A o,6192 O,2RIT 1./$g, t1. 021 .Z Q o.i 5 925 o.68f 0, 25 . 1 8. .321 e 91 o. o.AG33o, o? iI..qL_ .3zta qi. l O.07 o.vI j. ,16.o.ods.o 1 -Xt[ IJ.. _TT/ a,771 6 10to6 o.Zl07 -. aSq . ,0 0a23dq a.7.Z .lo O.23Z1 o.O6&l a 0475 0. 246 0.100 !.oa _ o~t 1,056 oo878 o. z398-470 *54O n .lS3 .. vOa, 1,080 0143 ._ n.4 ) 8~ a. o.lsC, . .oY o.79I . S.'1 o. 3. -0.6RO1.6I-0 O. &G1 ~ X'c(%/)_tc(Day ) " i A" STRAIN 7 c Controlled Strain Presheor TIME m DURING i I Final ) -- T hC 1,031 tc(Day) in o.sn77 o.oq? n LABORATORY REMARKS: ENGINEERING INSTITUTE OF TECHNOLOGY 496 _ _ _q? ±,iq Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE Eo/J42z SOIL V',491' PROJECT TIME STRAIN (Hr.) ( O/o)v O,Zq .1.1 . 5±36 o.,ZB O.43.L .?7 O..2Jq 0.44 6 a -s.'/ 7.q * o.4:'7 1.4e 0 .4;4t o.4S:3 .4. _o.U Ja.4szi 113. 1_ 182. _ 1_. i1 q S !_5.¢L IL. 71 0.34.2. I. /' o.4ylz I.2f.. IM* 172 O.&¢&t I Z1rlqo.1-.3 Z 12zq o .11&l o 1 76 o.3099 10o7&7 Q4 0.3o_ __i&_ 0o•l/1a. D.3Oc.7 11 o. .glq . 6 1 17Z t.O.36S' _O._ a.¶ I .2 . l1z9 110 .S I.e'& o.3&S' a.!08 I. oe6 03968 o.eqcl .0O 31 7 L O, I.oI I, II& .',4 ._ 233 s1zq 54 o. 0.31:3 0.4211 -o.6'76 atJ. i±io, 312q 1-'6 , .. 2 0.41 -O06 9,~4L 0.129 a 1132..o.ai2z .219 a,.Gl lq 41e laolSor"G o.'4. 7 o. Ilo zq 14 4 12. -o 1 REMARKS aJ2q 6,1 ,/ 1. 1.281 o,: T7' -o. 2oR NO. EDS-2. V 0.6L. 2 1.m21 .. _ m Il.Z19 a.. 1 7 .,,21q _.44_ DSS Th . 21' I Zq o.44 .. -o z7. 7.07 __. 19 q 2 oq. 2. .I ___ a2 .o O.9268 -az. S' 5.~l TYPE OF TEST .h h O' Au 4.2 17. C-4 . A.12 o. __2___ __?_ 2t 0.213 ±4. 2t 0.71. o.g6 oh! 235'L 1972 .o . o. Iq L o..3&$!8 0. . o. , a, z.~'~ oz±. 4 2a.II6 h '2 .z" 25. I19 0//48 6+ 18.27 o.~tAg 6. 0.112. .=a-zo/97 t-2t~ 2:2,2~ 3.3') o. Z~a4&s1 .:t0109 0.,664, o,Iq7 .,?07 366o 02 o.04 24 I ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. REMARKS: LABORATORY MECHANICS SOIL DEPT. OF CIVIL ENGINEERING OF TECHNOLOGY INSTITUTE MASSACHUSETTS 497 _7 Sheet I of 2 SHEAR TEST DIRECT - SIMPLE D65-3 PROJECT 804z TYPE SOIL TYPE TESTED BY '3L V4up6D CLAY 7vc NO. ED5-3 OCR 8 - DEVICE6cov'O£. DATE (Stresses CONSOLIDATION ERSTvjlPJWp LOCATION OF TEST ' in'.knm) vm '2 rhc 8& V/) c(%)tc(D CDy) ocy) , j I g W e w % Initial . . )I H( S,%I Controlled Strain 1 Presheor I I I Rote (/o/Hr.) Final TIME STRAIN (Hr.) (%) Th AU avc 'vc ri .v SHEAR DURING , v REMARKS __ crvm °vm *oo o.a . & o.qq -O.~ -.671 L 0.&ql4 m 1?..4 -LaL - 1q o.'17 J .a 2i7 _a _.o 7 o,IIl' ao .'00 0.00 I.a&. a o8# aM.al2 o.6Z . 14.. I. 4i . 1 134 IIo oo -a. 1& o.2a9 J o,3 0 I&I # J.A0, 0.3LMk _i 8A A.SRg th0 .223 0.4 . A- I.0 1r.7 I a7q 1.144 a. tr o.o17 i.¢S el 0323 o,. .632 a dsr . 0.,2SS, 0 03,q a. 154 O.II 2Tq 1!81 o.1o -. ?22oI 0.3q. 9 2.3,. 244 aa .1 q- 3 1.321 (0. /2~ 1-24WaoSa S fl.gqj S. 661 A SIC . 3I 5; 7 s 02. _ 1 L -G,~1 7.77 caril a..5±k. i_49L &off _ g 9.le .69<3.?., q.'L4 .OS -4 o.lo _ X.K S 0653 a 0&1S7 la. 0aOL? I. 3a o,1'74 -O., 30 _MAL 1953 o.37 6 , 13(. oo,77,0 -3q JCS Q.31 .38181. o._Q8 -. 4o 8.SS1 - a,~l& L.72 1. J85' a1 -a._0z _.7_ I8 0,044 )0. 0 39L 070 o 3 .32 S3,?14i aos - {32; 1 33( .Qo 3-,q 0±W - oA40I.. tz7 7±i 4..z2 c-a'l Ho 1,335 a..'T4 Stress r Th c ' _______q a.. 71 __ _._q a.0. 084o &)go .'q 3 Ila 0,181 a.13 Q o.1.44q 3 i2. lU/ q'Z .017' 1-41 6 .3ql 1.442. . 6 _ o678 o. 1q oO L6 .l q aj .QL!,& o'lq-o n. .4't& o46 O.o06 o. lt_ L.q/_ # /4 o,:'q _o,~?c: .fp8 l* i.?, . ~,-;,r,e~otl! o _ ___ a.6o& r -0~~~~~~~~,o6,1-0,-g1j47 0-47 1 I-? 4* booz8.] c,.Wo Q-444 SOIL MECHANICS LABO R A TOR Y DEPT. OF CIVIL ENGINEERING OF TECHNOLOGY MASSACHUSETTS INSTITUTE 498 REMARKS: _ Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE SOIL PROJECT 8ot- TYPE OF TEST s ~Ps [;)- NO. DS-3 O'v IREMIARKSQ . TIME STRAIN (Hr.) (%) /X U -vc ovc -Th rh fi I vm Ovc .49S, 10. 13f 0.183 /. qo I Zo 1503 I 1. 4 I.$563, o.-&z? I11.96 O Is. "& IIa.o 1?*.5oo o.41S' ...~o3 6. f/~s A.6-&33 (,~,3 -_6.S43 6. B.q _ O. S?+ f414 .4#4 _o.olq I.S 1.534 0,42S ..o41 I 0.&46 Q.085 0.086s o.08 0.206 0.gR'; io.41 .SI9 - 6, $1q+ 11X511 d.~64 6.614 o. G# O. Z06 o.68S4 1.S639 o.f,2q o.264 Im ~o109 0.O59 ooam . OR(> 1.0o86 06.473 0,26e e,6P,7 .1 Ia. J.I q' 0.420 0.20612 -. g'esli sg7 -. 111~ 6 lSI9 Is.qq& .-o. S I o.alq I.4o1 IS.(o A.54 _.61 1.41 .369 0-422 a.4" I6.17 .o'11 o.2il .S'47 JL338 &4s9 gL414 21.o a. S36 n.,Z3 00613 J4291 r &CZZ =~~~~~~~~~~~~~~~~~~~~.. 4L 2A.q6 2s. 1,2 71 aC¢21& G.j/Z .4t Q-44 -O. .4q -6. S1 0, 5.81 o.42S I.6fz9 0,425- I a. 0&'7 1,212 I .169 O ./Ss , ,1.5 0A10- a, o65 I.I4 1- _dq2 i i I i . . l . SOIL MECHANICS DEPT. OF CIVIL MASSACHUSETTS . l . I . RE MARKS: LABORATORY ENGINEERING OF INSTITUTE I TECHNOLOGY 499 SECTION D.2-5 TABULATION OF TEST DATA FROM CKoUDSS TESTS ON INCLINED EAST WINDSOR SAMPLES 500 10 Note: REFERENCES ASCE ASTM = American Society of Civil Engineers = American Society of Testing and Materials JGED = Journal of Geotechnical Engineering Division JSMFD = Journal of the Soil Mechanics and Foundation Division ICSMFE = International Conference on Soil Mechanics and Foundation Engineering Amerasinghe, S.F. and Perry, R.H.G (1975), "The Anisotropy in Heavily Overconsolidated Kaolin," JGED, ASCE, Vol. 100, No. GT 12, pp. 1277-1291. Bailey, W.A. and Christian, J.T. (1969), "ICES-LEASE-I, A Problem Oriented Language for Slope Stability Analyses," Res. Report R-69-22, Dept. of Civil Eng., MIT, 56 p. Baker, W.H. and Krizek, R.J.,(1970),"Mohr-Coulomb Strength Theory for Anisotropic Soils," JSMFD, Vol. 96, No. 3M1, pp. 269-292. Beere, T. (1969), "Studies of Yield Stress and Time Effect in Drammen Clay," Bolkesjo Sym. on Shear Strength and Consolidation of Normally Consolidated Clays, pp. 31-36. Beere, T. and Bjerrum, L. (1973), "Shear Strength of Normally Consolidated Clays," 8th ICSMFE, Moscow, Vol. 1, pp. 39-49. Bishop, A.W. (1966), "Strength of Soils as Engineering Material," 6th Rankin Lecture, Getechnique, Vol. 16, No. 2, pp. 89-130. Bishop, A.W. and Henkel, D.J. (1962), The Measurement of Soil Properties in the Triaxial Tests, St. Martin's Press, 2nd Edition. Bishop, A.W., Webb, D.L. and Lewin, P.I. (1965), "Undisturbed Samples of London Clay from the Ashford Common Shaft; Strength-Effective Stress Relationships," Geotechnique, Vol. 15, No. 1, pp. 1-31. Bjerrum, L. (1972), "Embankments on Soft Ground," Proc. ASCE Spec. Conf. on Performance of Earth and Earth-Supported Structures, Vol. 2, Purdue University, pp. 1-54. Bjerrun, L. (1972), "Problems of Soil Mechanics and Construction on Soft Clays," State-of-the-Art Report, Session 4, Proc. 8th ICSMFE, Moscow, Vol. 3, pp. 109-159. 381 Bjerrum, L. and Landva, A. (1966), "Direct Simple-Shear Tests on a Norwegian pp. 1-20. Quick Clay," Geotechnique, Vol. 16, No. 1, Bovee, R.B. and Ladd, C.C. (1970), "MIT Plane Strain Device," Research in Earth Physics, Research Report R-70-24, Soil Publication No. 257, Dept. of Civil Eng., MIT, 121 pp. Bozozuk, M. (1970), "Effect of Sampling, Size and Storage on Test Results for Marine Clay," ASTM, STP 483, pp. 121-131. Bozozuk, M. and Leonards, G.A. (1972), "The Gloucester Test Fill," Proc. ASCE Spec. Conf. on Performance of Earth and Earth-Supported Structures, Vol. 1, Purdue University, pp. 299-317. Casagrande, A. and Carillo, N. (1944), "Shear Failure of Anisotropic Materials," J. BSCE; reprinted in Contributions to Soil Mechanics 1941-1953, pp. 122-135. D'Appolonia, D.J. (1968), "Prediction of Stress and Deformation for Undrained Conditions," Ph. D. Thesis, Dept. of Civil Eng., MIT, Cambridge. D'Appolonia, D.J., Poulos, H.G. and Ladd, C.C. (1971), "Initial Settlement of Structures on Clay," JSMFD, ASCE, Vol. 97, SM 10, pp. 1359-1377. Davis, E.H. and Poulos, H.G. (1967), "Laboratory Investigations of the Effects of Sampling," Civil Eng. Trans., Inst. of Eng., Australia, Vol. CE 9, No. 1, pp. 86-94. Davis, E.H. and Christian, J.T. (1971), "Bearing Capacity of Anisotropic Cohesive Soil," JSMFD, ASCE, Vol. 97, No. SM5, pp. 753-769. Dickey, J.W., Ladd, C.C., and Rixner, J.J. (1968), "A Plane Strain Shear Device for Testing Clays," Res. Report R68-3, No. 237, Dept. of Civil Eng., MIT. Duncan, J.M. and Dunlop, P. (1969), "Behavior of Soils in Simple Shear Tests," 7th ICSMFE, Mexico, Vol. 1, pp. 101-109. Duncan, J.M. and Seed, H.B. (1966a), "Anisotropy and Stress Reorientation in Clay," JSMFD, ASCE, Vol. 92, No. SM2, pp. 21-50. Duncan, J.M. and Seed, H.B. (1966b), "Strength Variation Along Failure Surface in Clay," JSMFD, ASCE, Vol. 92, NO. SM 6, pp. 81-104. Eden, W.J. (1955), "A Laboratory Study of Varved Clay from Steep Rock Lake, Ontario," American Journal of Science, Vol. 253, No. 11, pp. 659-674. 382 Hansen, J.B. and Gibson, R.E. (1949), "Undrained Shear Strengths of Anisotropically Consolidated Clays," Geotechnique, Vol. 1, No. 3, pp. 189-204. Healy, K. (1967), Unpublished Data, Dept. of Civil Eng., University of Connecticut. Henkel, D.J. and Wade, N.H. (1966), "Plane Strain Tests on Saturated Remolded Clay," JSMFD, ASCE, Vol. 92, No. SM 6, pp. 67-80. Hill, R. (1950), The Mathematical Theory of Plasticity, Clarendon Press, Oxford. Hvorslev, M.J. (1960), "Physical Components of the Shear Strength of Saturated Clays," ASCE, Research Conference on Shear Strength of Cohesive Soils, Boulder, CO, pp. 169-273. Jakobson, B. (1952), The Landslide at Surte on the Gata River," Proc. Roy. Swed. Geot. Inst., No. 5, 121 p. Jakobson, B. (1955), "Isotropy of Clays,"' Geotechnique, Vol. 5, No. 1, pp. 23-28. Kenney, T.C. and Chan, H.T. (1972), "Use of Radiographs in a Geotechnical Investigation of Varved Soil," Can. Geotech. Journal, Vol. 9, No. 3, pp. 195-205. Lacasse, S.M., Connell, D.H. and Ladd, C.C. (1972), "Interim Report on the Shear Strength of Connecticut Valley Varved Clays," Dept. of Civil Eng. Research Report R72-16, Soil Pub. No. 299, MIT, 121 p.. Lacasse, S.M., Ladd, C.C. (1973), "Behavior of Embankments on New Liskeard Varved Clay," Res. Report R73-44, No. 327, Dept. of Civil Eng., No. 327, MIT, 270 p. Lacasse, S.M., Ladd, C.C. and Barsvary, A.K. (1975), "Undrained Behavior of Embankments on New Liskeard Varved Clay," Department of Civil Eng., Constructed Facilities Div. Pub. No. R75-44, 55 p.Ladd, C.C. (1975), "Foundation Design of Embankments Constructed on Connecticut Valley Varved Clays," Res. Report R75-7, No. 343, Dept. of Civil Eng., MIT, 439 p. Ladd, C.C., Bovee, R.B., Edgers, L. and Rixner, J.J. (1971), "Consolidated-Undrained Plane Strain Shear Tests on Boston Blue clay," Res. Report R71-13, No. 273, Dept. of Civil Eng., MIT, 243 p. 383 Ladd, C.C. and Edgers, L. (1972), "Consolidated-Undrained Direct-Simple Shear Tests on Saturated Clays," Res. Report R72-82, No. 284, Dept. of Civil Eng., MIT, 354 p. Ladd, C.C. and Foott, R. (1974), "New Design Procedures for Stability of Soft Clays," JGED, ASCE, Vol. 100, No. GT7, pp. 763-786. Ladd, C.C. and Foott, R. (1977), "Foundation Design of Embankments Constructed on Varved Clays," Report for US Department of Trans. Fed. Highway Admin., Contract No. DOT-FH-118973, 234 pp. Ladd, C.C., Foott, R., Ishihara, K., Poulos, H.G. and Schlosser, F. (1977), "Stress-Deformation and Strength Characteristics," State-of-the-Art Report, Session 1, Proc. 9th ICSMFE, Tokyo, 74 p. Ladd, C.C. and Lambe, T.W. (1963), "The Strength of 'Undisturbed' Clay Determined from Undrained Tests," ASTM, STP 361, pp. 342-371. Ladd, C.C. and Varallyay, J. (1965), "The Influence of Stress System on the Behavior of Saturated Clays During Undrained Shear," Res. Report R65-11, Dept. of Civil Eng., MIT, 267 p. Ladd, C.C. and Wissa, A.E.Z. (1970), "Geology and Engineering Properties of Connecticut Valley Varved Clays with Special Reference to Embankment Construction," Res. Report R70-56, No. 264, Dept. of Civil Eng., MIT. Lambe, T.W. (1953), "The Structure of Inorganic Soil," ASCE Proc., Vol. 79, Proc. Separate No. 315. Lambe, T.W. (1958), The Structure of Compacted Clay," JSMFD, ASCE, Vol. 84, No. SM2, Paper No. 1654, 34 p. Lo, K.Y. (1965), "Stability of Slopes in Anisotropic Soils," JSMFD, ASCE, Vol. 91, No. SM4, pp. 85-106. Lo, K.Y. (1966), Closure: "Stability of Slopes in Anisotropic Soils," JSMFD, ASCE, Vol. 92, SM 4, pp. 77-82. Lo, K.Y. and Millican, V. (1967), "Shear Strength Properties of Two Stratified Clays," JSMFD, ASCE, Vol. 93, No. SM 1, pp. 1-15. Lucks, A.S., Christian, J.T., Brandow, G.E. and Hoeg, K. (1972), "Stress Conditions in the NGI Simple Shear Tests," Technical Note, JSMFD, ASCE, Vol. 98, No. SM 1, pp. 155-160. 384 Martin, R.T. (1962), "Research on the Physical Properties of Marine Soils," Res. Report R 62-42, Dept. of Civil Eng., MIT. Martin, R.T. and Ladd, C.C. (1975), "Fabric of Consolidated Kaolinite," Clay and Clay Minerals, Vol. 23, pp. 17-25. Merkle, D.H. (1971), "The Effective Stress Mechanics of Undrained Shear Strength," Ph. D. Thesis, Dept. of Civil Eng., MIT, 802 p. Milovic, D.M. (1970), "Effect of Sampling on Some Soil Characteristics," ASTM, STP 483, pp. 14-179. Mitchell, R.J. (1967), "Application of Critical State Theories," Ph. D. Thesis, University of Cambridge. Mitchell, R.J. (1972), "Some Deviation from Isotropy in a Lightly Overconsolidated Clay," Geotechnique, Vol. 22, No. 3, pp. 459-467. Morgenstern, N.R. and Price, V.E. (1965), "An Analysis of the Stability of General Slip Surfaces," Geotechnique, Vol. 15, pp. 79-83. NGI (1972), "General Report on Laboratory Tests on Samples from the Test Site at Matagami," Report No. 71307-3. Parson, J.D. (1976), "New York's Glacial Lake Formation of Varved Silt and Clay," JGED, ASCE, Vol. 102, No. GT 6, pp. 605-638. Perry, R.H.G. (1971), "Stability Analysis for Low Embankments on Soft Clays," Proc. Roscoe Memorial Symp. on StressStrain Behavior of Soils, Cambridge, pp. 643-668. Perry, R.H.G. and Nadarajah, V. (1974), "Anisotropy in a Natural Soft Clayey Silt," Engineering Geology, Vol. 8, pp. 287309. Quigley, RM. and oqunbade jo, T.A. (1972), "Clay Layer Fabric and Oedometer Consolidation of a Soft Varved Clay," Can. Geot. Journal, Vol. 9, No. 2, pp. 165-175. Sangrey, D.A. (1975), "Normalized Design Procedures in Sensitive Clays," JGED, ASCE, Vol. 101, No. GT 11, pp. 11811187. Saxena, S.K., edberg, J. and Ladd, C.C. (1974), "Results of Special Laboratory Testing Program on Hackensack Valley Varved Clay, Res. Report R74-66, No. 342, MIT. 385 Schmertmann, J.M. (1955), "The Undisturbed Consolidation of Clay," Trans. ASCE, Vol. 120, pp. 1201-1233. Schkertmann, ?.JH.*ard J;O Osterberg (1968) "An Experimental Study of the Development of Cohesion and Friction with Axial Strain in Saturated Cohesive Soils," ASCE, Research Conference on Shear Strength of Cohesive Soils, Boulder CO, pp. 643-649. Scott, R.F. (1963), Principal of Soil Mechanics, AddisonWesley. Skempton, A.W. (1948), "A Study of the Immediate Triaxial Test on Cohesive Soils," Proc. 2nd ICSMFE, Rotterdam, Vol. 1, pp. 192-196. Skempton. A.W. (1954), "The Pore Pressure Coefficient A and B." Geotechnique, Vol. 14, pp. 143-147. Soydemir, C. (1972), "Anisotropy in Undrained Shear Strength Observed Through Special Simple Shear Tests," NGI Internal Report 50320-8. Townsend, D.L., Hughes, G.T. and Cruickhank, J.A. (1965), "The Effect of Pore Pressure on the Undrained Strength of a Varved Clay," Proc. 6th ICSMFE, Montreal, Vol. 1, pp. 385389. Vaid, YP. and Campanella, R.G. (1974), "Triaxial and Plane Strain Behavior of Natural Clay," JGED, ASCE, Vol. 100, No. GT 3, pp. 207-224. Ward, W.H., Marsland, A. and Samuds, S.G. (1965), "Properties of the London Clay at the Ashford Common Shaft; In-Situ and Undrained Strength Tests," Geotechnique Vol. 15, No. 4, pp. 321-344. 386 BIOGRAPHY Surachat Sambhandharaksa was born to Mr. Chanai and Mrs. Sabha Sambhandharaksa on Feb. 24, 1944 in Bangkok, Thailand. He attended high school in Bangkok, Thailand. In 1962, he got a Colombo plan scholarship to study at the University of New South Wales in Sydney, Australia and in 1967 was awarded the degree of Bachelor of Engineering. While an undergradaute, he was employed for two 4-month periods by the Department of Main Roads in New South Wales, Australia. The writer went to work as an instructor at Chulalongkorn University for one year, before continuing his study under a scholarship from the Asian Institute of Technology where in 1970 he was awarded the Master of Engineering. He again lectured at Chulalongkorn University. In 1971, he and Dr, Za-Chieh Moh, his thesis advisor at the Asian Institute of Technology, wrote a paper entitled, "Effects of Salt Content on Thixotropic Behavior of a Compacted Clay,"~ published in the Proceedings of the First Australia-New Zealand Conference on Geomechanics, Melbourne, 1971. On leave of absence from Chulalongkorn University since 1971, he went to study at Northwestern University for a year before transferring to MIT to study for his Doctor of Science. 387 APPENDIX A Prefix indicates a change Suffix f indicates a final or failure condition A bar over a stress indicates an effective stress A bar over a property indicates value in terms of effective stress. INDEX AND CLASSIFICATION PROPERTIES eo - Initial void ratio Gs - Specific gravity LI - Liquidity index PI - Plasticity index w - Water content WL - Liquid limit WN - Natural water content W - Plastic limit P Bouyant unit weight Y~b Yt ¥w - Total unit weight - -w ~ Unit weight of water STRESSES, STRAINS, MODULUS, AND STRENGTH PATRAMTERS a a a/-a - Pore pressure parameter (Eq. 2.9) - Intercept of qf vs. - f failure envelope Normalized intercept of qf/avm vs. Pf/vm envelope 388 failure A - Skempton's pore pressure parameter A Af(V) - Skempton's pore pressure parameter A at failure for vertical loading Af(PSC) - Skempton's pore pressure parameter A at failure from K consolidated plane strain compression test Af(H) - Skempton's pore pressure parameter A at failure for horizontal loading Af(PSE) - Skempton's pore pressure parameter A at failure from K o consolidated plane strain extension test Af(45 °) - Skempton's pore pressure parameter A at failure for inclined (45° ) loading Af(DSS) - Skempton's pore pressure parameter A at failure from Ko consolidated direct simple shear test B - Skempton's pore pressure parameter B = Au/ac b/a - Axes of Davis-Christian (1971) elliptical strength relationship c, - Intercept of Mohr-Coulomb failure envelope 0~~~~~~~~~~ c/a,c vm 6vi Normalized intercept of normalized Mohr-Coulomb failure envelope E, E - Young's modulus Eu - Undrained secant E EU (H) Eu (V) - Undrained secant E from horizontal loading - Undrained secant E from vertical loading E u (45°) Undrained secant E from inclined (45°) loading f - Initial shear stress ratio = (-Ko)/[2Su(V)/Avo) 0 u ~vo G - Shear Modulus Gi - Initial G for hyperbolic stress-strain model Gy - Yielded G for hyperbolic stress-strain model K - Bulk modulus Gy Kc c/ a ~vch~c 389 Ko Coefficient of earth pressure at rest - Ks Anisotropic strength ratio = qf(H)/qf(V) NESE Normalized effective stress envelope, the plot in terms of qf/avm versus f/;vm NESE - Normalized effective stress envelope, the plot in terms of aff/vm versus Tff/avm OCR - Overconsolidation ratio = avm/avo, avm(L)/avc 0.5(o P, P + aoh) 1/ 2 ( + ah) - 0.5(av - oh) or 1/2 ( q - a3) qf - q at failure qf(V) - qf from vertical loading qf(H) - qf from horizontal loading qf(4 5 °) - qf from inclined (45'°) loading Parameter for hyperbolic stress strain model R. Rf St - - Su(V) Su(45°) Su (undisturbed)/Su (remolded) Undrained shear strength = qf or Su Su (H) Sensitivity Su from horizontal loading Su from vertical loading Su from inclined (45° loading - - Su (DSS) Tff = qfcos~ Su from direct simple shear test from plane strain compression test Su (PSC) - S Su (PSE) - S u from plane strain SCF - Strain compatibility factor (see Table 8.4) SR - Strength ratio (see Fig. 5.24) t - Time at failure f u extension Pore water pressure - u m ud u for undrained condition u from field measurement Udn 390 test - u at undrained failure a5 - Slope of qf vs. pf failure envelope a - Angle between the failure plane and the horizontal plane 6 - Angle between the normal to the failure plane and the major principal stress axis B - Angle between - Varve inclination - Shear strain - Linear strain - Axial strain Uu e Y, f C a a lf and vertical direction sv Vertical strain Svol Volumetric strain Field vane correction factor V, v - Poisson's ratio a, a - Normal total stress, normal effective stress °1' 2' :3 (a 1/3)max c ac a c Principal stress Maximum obliquity - Confining pressure (isotropic) - Consolidation pressure (isotropic) Offi aff- Normal stress on failure plane at failure ah - Horizontal normal stress ah - Norizontal consolidation stress - Octahedral stress a Ps as - Isotropic stress of perfect sample - Pre-shear effective stress of UUC sample v - Vertical consolidation stress - Final vertical effective stress ~hc 0 oct 5 avf 391 - vo Initial vertical effective stress a- Maximum past pressure aVm (L) Laboratory maximum past pressure vm Ovm(L a - Normal stress on a plane with inclinations to the horizontal plane - Initial a ,a a ao a0 ~~T -Shear stress -T T on failure plane at failure ff Th - Maximum Thm Thmax T oct Ta T on horizontal plane (direct-simple shear test) Th - Octahedral shear stress - T on a plane with inclination plane T Initial T Tf T ¢, ~T to the horizontal at failure Slope of Mohr-Coulomb or normalized Mohr-Coulomb failure envelope CONSOLIDATION, STABILITY AND SETTLEMENT CONSOLIDATION, STABILITY AND SETTLEMENT B - Width of loaded area Coefficient of consolidation for vertical flow Cv CR - Virgin compression ratio FS - Factor of Safety H - Depth of foundation clay or height of clay layer I_ Influence factor for elastic settlement (Eq. 8.1) P PC- Quasi-consolidation pressure RR - Recompression ratio SR - Settlement ratio = P -Pe 392 1 time t t required for primary consolidation t p Degree of consolidation U Average degree of consolidation UA Anglebetween failure surface and horizontal direction for plane strain compression failure surface A Angle between failure surface and horizontal direction for plane strain extension failure surface 0 p "Elastic" settlement Pe Initial settlement Pi CONSOLIDATION AND STRENGTH TESTS CD Consolidated-drained shear test CDDS - CD direct shear test CRSC - Constant rate of strain consolidation test CU Consolidated-undrained shear test CIU Isotropically consolidated-undrained shear test CIUC CIU triaxial compression test CIUE - Ko consolidated-undrained shear test CK U 0o CKoUC CIU triaxial extension test - CKoU triaxial compression test CKoUDSS CKoU direct simple shear test CKoUDSS (C) CK U direct simple shear test run on inclined sample and sheared by increasing shear stress CK UDSS(E) CK U direct simple shear test run on inclined sample and sheared by decreasing shear stress CKoUE CKoUE - CKoU triaxial extension test 393 CKoUPSC CKoU plane strain compression test CKoUPSE CKoU plane strain extension test DSS Direct-simple shear FV Field vane test PSC Plane strain compression (alf = Oavf) PSE Plane strain extension TC Triaxial compression TE Triaxial extension UC Unconfined compression UU Unconsolidated-undrained shear test UUC UU triaxial compression test. (lf = hf) MISCELLANEOUS CVVC Connecticut Valley varved clays FV Field vane M-C Mohr-Coulomb M-P Morgenstern and Price MPPR Maximum Past Pressure Ratio = MOC Method of Consolidation NC Normally consolidated OC Over consolidated PS Plane strain a 394 (L) vm APPENDIX B BEST ESTIMATES* OF STRESS-STRAIN-STRENGTH DATA OF CONNECTICUT VALLEY VARVED CLAYS Summary of best estimates of test data from SHANSEP CKoUC, CK0 UE and CKoUDSS tests are presented in Tables B-1 through B-3. Figures B-1 through B-6 show best estimates of normalized stress-strain curves and normalized stress paths from CKoUC, CKoUE and CKoUDSS tests on NC and OC samples. The normalized stress-strain curves from CKoUPSC and CKUPSE tests on NC samples 0 ~0 are shown in Figs. 5.20 amd 5.21. The following are the lists of tables and figures LIST OF TABLES B-1 Best Estimates of Test Data from CKoUC Tests on NC and OC Samples from the Connecticut Valley B-2 Best Estimates of Test Data from CKoUDSS Tests on NC and OC Samples from the Connecticut Valley B-3 Best Estimates of Test Data from CKoUE Tests on NC and OC Samples from the Connecticut Valley LIST OF FIGURES B-1 Normalized Stress-Strain Curves from CKOU Triaxial Compression and Extension Tests on Normally Consolidated Connecticut Valley Varved Clays B-2 Normalized Stress-Strain Curves from CKoU Triaxial Compression and Extension Tests on Overconsolidated Connecticut Valley Varved Clays: OCR=2 *Determined from average data of samples from Amherst, Northampton and East Windsor. 395 LIST OF FIGURES (Continued) B-3 Normalized Stress-Strain Curves from CK 0 U Triaxial Compression and Extension Tests on Overconsolidated Connecticut Valley Varved Clays: OCR=4 B-4 Normalized Stress Paths from CKoU Triaxial Compression and Extension Tests on Connecticut Valley Varved Clays B-5 Normalized Stress-Strain Curves from CKoUDSS Tests on Normally Consolidated and Overconsolidated Connecticut Valley Varved Clays B-6 Normalized Stress Paths from CKoUDSS Tests on Connecticut Valley Varved Clays 396 f-q I m C) E-4 ! ...... I.... IC %n i I I 01 i i I II - N r'I) 0 6 6co I - 0 0 +1 I -.0. - 0 6 i I- - ii mm iii 0 i 0C z 0 U I o U 0o rlt N 0 t II 0 III 1*' U 4 U P: - N4 I A - l P4 l L i E ;I o0 0 o o0 0 I z U' 'C' I 0 co d a . I I-9. u0 4, 0 0 ib 's w 4I 0O ... 0 +6 " +1 0 45 II2 r 0w 4..: U 0 ,4" 0 I_ 0 Huz En -:D HZ: 8 6 0 o 45! 0 e 01 !- m% 6 1 7 - 'o 6 i,> .9, .7 I- 4-I a I 3- EH E-4 0, E-i q,. 0 -- - - -1 t - _ - I 0 I , _t . | . ... .. 0 %9 6 ........ os5 00 _ . .~~~~~l . 397 .......... . I G a) H-- 0 M) O 0 I I _ r '4 0 . x0 5) _ _ m 1c 44 Ui) U E-4 6 ; U) Z m 00 In~ P4 tp 0 +1 0 41 O- 1 ¶i r: r 0 OI I I 0 0 i 4-1 'I 0 -: 6 1 0 I 0 0 O O o . I 0 II U) E-4 U) CJ 0 = uU) -1 o cq II . 0O 9 +.'I 6- E-' U) o~~~~~~~ E-i __ .. . , .. . _ _ Oa En E' H U O m> 398 m I e..i .Q 'U 0 9' l - - - P: - = - - " i £ I a I o 6 la 1 rz~ U) r. . 04 Iim -. Is 0 0 9 0 41 N I-e- C- d tn 8 6 in -- U a, AC - 0 +enI LA liUn v3 Nin 0 ig- - - o.Ez to &! K- 0 - U) E M 0 0 E4 0 0 I P - 0 x 6co 0cn £ .E 0 m U 0 a) .Z a0 +1 r4 NP O-I O 0 -N To R .C 0- Ic rC) 0 r oa-. in 0o r- +, q- I<C Ia \ r4> E4 > 0 U). CA9 C+ 40 0 0 . . . . . wr 0 E-Z . _ U Z; WO E- . H EW 9 :: Ci 0 _A.._ r8. __ J .. 399 . _, "_ ._ 0.6 0.5 o 4 0.2. 0.1 ARC B11 - 0.I - 0,2. -0.4. -0.44 -A, I 0 o 2 4 6 6 10 14 18 NORMALIZED STRESS-STRAIN CURVES FROM CKoU TRIAXIAL COMPRESSION AND EXTENSION TESTS ON NORMALLY CONSOLIDATED CONNECTICUT VALLEY VARVED CLAYS Fig. B-1 400 aJ I. U 0.4 0,+ ..e o.t b do '4. -0.4 - ou. -0.0 -. 0 0. 0,0 0. (0 A0. CuT -T., CyOUc Tst- ~~~~~~~~~~~~~U. 0.I 0 -0.- _. } - - 6 STRAI_ 10 I~ .... AXIAL . ~~~~AX~IAL STP-,,/AI, 0/o - '4 NORMALIZED STRESS-STRAIN CURVES FROM CKOU TRIAXIAL COMPRESSION AND EXTENSION TESTS ON OVERCONSOLIDATED CONNECTICUT VALLEY VARVED CLAYS: OCR=2 Fig. B-2 401 1.Co 0.6 6v.6 0.4 -0,4 -0,6 -1.2. -t.6 1.0 c -c- Test cKoaie Test ~~~~~~~~CKgsUC, Tht A 0.5 OS C KoUE Test 0 NORMALIZED STRESS-STRAIN to CURVES FROM CKoU TRIAXIAL 14 COMPRESSION AND EXTENSION TESTS ON OVERCONSOLIDATED CONNECTICUT VALLEY VARVED CLAYS: OCR=4 Fig. B-3 402 0 0 I & 0z o cn Es4 U) E-4 z 0 o H UE rz z o~ C3 H 0 HU ~ Hoo rz.' 44 I. U) U) El Z C)> E-4> U zZ Z o o 6 m% 49 A0 6 0 403 I ola 6 g41 0.6 - 0.4 otc. I~~~~~o~ 0.2. . OCaq B '- C aid I- _ -_ ./ _ 0 0 I I 4 8 I l2 4. 8 12 I I .__ -. 20 4 20 Z4 U. o 0.4 AU. - 0 O.2 -0.4 - O.( 0o,4 0. Z 0,1 0o 0 16 Shear Stral n, % NORMALIZED STRESS-STRAIN CURVES FROM CK UDSS TESTS ON NORMALLY CONSOLIDATED AND OVERCONSOLIDATED CONNE8 TICUT VALLEY VARVED CLAYS Fig. B-5 404 9 1-.0 I co t .r-4 v] (n 44 H U zz 0 U z 0 z u) U) C) u) D O w EM u)q W u~ Un ~H En0 U) U) E-4 U) z Cs 6 t 405 o 66 0 APPENDIX C SUMMARY OF TEST RESULTS FROM CONNECTICUT VALLEY AND HACKENSACK VALLEY VARVED CLAYS Appendix C contains a summary of test results from UUC tests ,CIU and CKOU tests on NC and OC samples from Amherst, East Windsor, Northampton and Hackensack Valley with details of the testing conditions. The following are the lists of tables which are presented in this appendix. SUMMARY OF TEST RESULTS FROM AMHERST VARVED CLAY C.1 LIST OF TABLES C.l-l Locations of Amherst Samples Used for Undrained Strength Tests C.1-2 Summary of UUC Tests on Amherst Samples C.1-3 Summary of CIUC Tests on NC Amherst Samples at DifUE ferent Inclinations (e=0, 45, and 90) and Tests on NC Vertical and Horizontal Samples C.1-4 Summary of CKoUC Tests on NC and OC Amherst Samples C.1-5 Summary of CKoUE Tests on OC Amherst Samples C.1-6 Summary of CKoUDSS Tests on NC and OC Amherst Samples SUMMARY OF TESTS RESULTS FROM EAST WINDSOR VARVED CLAY C.2 LIST OF TABLES C.2-1 Summary of UUC Tests on East Windsor Samples at Different Inclinations C.2-2a Summary of CIUC Tests on NC and OC SHANSEP East Windsor Samples at Different Inclinations 406 C.2.2b Summary of CIUC Tests on OC SHANSEP East Windsor Samples at Different Inclinations C.2-3 Summary of CIUE Tests on NC and OC SHANSEP East Windsor (=0 and 90) Samples C.2-4 Summary of CKoUC Tests on NC and OC SHANSEP East Windsor Vertical Samples C.2-5 Summary of CKoUE Tests on NC and OC SHANSEP East Windsor Vertical Samples C.2-6 Summary of CKoUC, CKoUE, and CIUC (=0, 45, 90) Tests on OC RECOMPRESSION East Windsor Samples C.2-7 Summary of CKoUDSS Tests on NC and OC East Windsor SHANSEP Samples C.2-8 Summary of CKoUDSS Tests on NC SHANSEP Inclined East Windsor Samples SUMMARY OF TEST RESULTS FROM NORTHAMPTON VARVED CLAY C.3 LIST OF TABLES C.3-1 Summary of CKoUC, CKoUPSC, and CKoUPSE Tests on NC Northampton Varved Cay C.3-2 Summary of CKOUDSS Tests on NC and OC SHANSEP Northampton Varved Clay C.3-3 Summary of CDDS Tests on NC and OC Northampton Varved Clay SUMMARY OF TEST RESULTS FROM HACKENSACK VALLEY VARVED CLAY C.4 NOTE: Additional data from Hackensack Valley varved clay can be obtained from Saxena et al. (1974). LIST OF TABLES C.4-1 Summary of CIUC, CKoUC Tests on NC and of CKoUDSS Tests on NC and OC SHANSEP Hackensack Valley Varved Clay Samples 407 SUMMARY OF TEST DATA FROM CIU AND CKoU TESTS ON SHANSEP AND RECOMPRESSION AMHERST SAMPLES 408 - ? - - -- -~ ........ [ - - - 0 U) E-1 U) Fl-- IP 0 a Uo E-4 - -- |- , 010 w80 s 0 -- a 0 O 0 0o i |- G1) r-Iq . - - - E-, /.' \C I" .N lb.1 6 U 14 6 N . l I 1,, o3 O E-4 0z i i iI C i, U I 0 i \9 'i rLI J~ l N 0. - SO : H Uo H 0 T O _C 0 '? - 7 I -N 0 U3 P; 0 rT4 VO in , _ , , ti~l I O ,! . Ir U' ) 0 * I= ! m U .IL ._ $Z n- 0. 2 us CL 1! t-.. IL v_ F0 Of 0 F -) w -4 I 0 rz | U "Y4. IIIC _;F 'L Q ' <1C E Q: A _ I 1 I I1 + fs I % < V W 4 C WI f4 C< q 409 Iw ; 0. I - - _] CN I ,--I . H .E i r 1L w- 'T .I 1 !a I 1 C_ 4- t4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ !-i 'U~~~~~.~ t g ~rL l 4.~~ ~9I E~~ r -4. 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A I? - I IN I la . ei cc, Nfo s - I 0 _ eJ 6 io i o .. . .. . .. .. . iI U) 'p V ------ ------0 i .L) 0 'a .-- -J Il I -.. Qj U> I., II't . ~-a i Ca\4j '1 I .X -_= ! M. ~ . ^ (I ;" E '~~ '-, n _-'o U -4- ~ eJ I 0 =,~ 41 I~~o . - ._ .. .. ... . . ~~~~~~~~~~I 0 1 (CO i 1 - Wh I IL , . . i ! 0 - = - t-iO - - -"-K .. ...... .... . ...... T ......... .,. i O ij U) C') n; - n U U) wo- 0 I 0 -I - z:_- i I Vfl 9 0 0 ID _____ *o or-K-1 - - __ ~ ~o ~Oo 9 ccS __o -i ..I~ 414 ~ -~ . SUMMARY OF TEST DATA FROM CIU AND CKoU TESTS ON SHANSEP AND RECOMPRESSION EAST WINDSOR SAMPLES 415 r-4 I N d H rU) z0 E- H Z H -4 U Z H - 1: E4 u z H Z O -' 0~~~~~~~0 ' 1'--0V7~ * ~ V 9- 4 En 0z H U) P 0U) C; ojI E4 H ~~~~o 0 V) ~~~~~ ~J 0 U U) A_ w k~~~~ To 0; ,4) ~-.: im--- (n -Y ,¢~~~ LIJ .- .zz:.:r_ 6 J¢¢ IC 4" !> so~~~~~~~~ -4c-* 416 - - - - I - I 9 I I I o6 a Ur~ Z; 4O rLI I-t 2 o I '4 o iD I H - .l -l - i- 0 0 0 6 . 1 uica,-g HH 3 .9 - --,I do En . . ~___. ~ Z . - O\.f8Z I - I I O - . 5. ,.&.. U^ In z s_ -) O 0 i ('4 to4 0 I C ,0 n Lr 41& pl 6 V- d __ I (J 4-3 En % 9.4 67" 'Lu - 0 o 8 61 ,., 66( 0 N- ('4 8 6 lHuz :o N4 _ H 44... ,,, . 0 0 06 I O '0- O O CQ N, %n at 0m O _ C _% a _( O 1 4 I .4 w 0 \9 00o 0 Nl 0 a ¢N O Cs Cl 10 Ln t7 mI? 0 fo sSoM P-*-R---9-b To cq 1 a 0 I 6CO_ - In S--- 0 't * - 0o 0 o S 0 t9? r- r-00 ,4 d: IH un il LU 0 0 I .. H I 1¢1 0 o O 0 _.' I y * C5 C, U o rz moc wI tom I$ ii - 417 :_ 7 I" ; ,, i - IT . ~s. : . . o6 r 00 0 4 o to e d ' 0¢ C6 %a 00 _1 0 _ 0 9 r- 0 6 0 In I .- o0 6 O In o - 0 $cv 0 O O %9 co 0 0 0a °D H U)H 7= o6 0C4 $ W rz t- co i Iiin_D 0 lto . : 0 Z vpti4 _ft - 40 .. '4 E1 cc% I ) ziii r:0 H I .0 .fl. C4 0 E ' IC In Cl) U) H U) H N 0 2 , .. N m m 0E< o 'S. ;T ___ In 06 N 4 U) HU z 6 ; O I AO in H P4No 0Z m U) 6 t -: tO __ In N rzl 0 V 0 I-- 66 'V tO __ a 6 _ 0- _ I 0 w 0- o X 'd t- I -3L.. oa I CDV U) rz- f a: 6 -b-.\ l -I N- Ca I - d ,-4 o E-1 zo i o -. N0 -- IU 0 -a ' - - - a H -- O " - r-. a 0 N - - - w | -- w o.- . 0- zite- U) .0 - o N N zH z t-. . c'1, ! p ch H f paq 1 1161 I~ I* A _'r - I, h :S VI- 4: - H %I.,I (rv 0U)_ , . _ _ ... . 19 ,.__ _. _ o . ___..____ b s _ IC) CO a - 3 .. £cc A 4- . o V U) z _ . O .. 00 ? 2 _-W _- A~I 0~ t ,e-i t g _ _ . 0 __ 49 _ _ _ a~ . %t co 0to |H U) U) 2 O r x ta-t - x -A L'S Q1,6C-1hl _ P d~ .4 _ oe _ .... . 1._. t: _ C mN 4% 6 __ _, tl; -i 41- b_ qwi L4- 8 '. L a4 e w Q, _ _. o "'r co o .6 a w cn 6 o _ - 0 0 0 n r- o o o. % 24. - d 0 ._ .-+ la I0 0 O~0 po - '0 - o 0 . - .. ) 0 6 N . I I j -^ 0o il _ le n t LAU - 6 N 6 It Oco Z c'J T. ly ___H O ,g · .- 0 I0 '0 0 6 rv _ C4 n, - , 0 6 _ 'd X I0 c 5 1. CO _ 0NO 0 _ E-1 i 0 0 9 eN ! .. t IF 0 _ ____ 0 0 0 4# 0U) P 4. R m- '0 06 r H 0 .I,7 w.. -. i 21 _ I0 06 - Ioll I _ .. _. i~ 00 0 * 1:So ,go0.- r ... U) lz 40 i'. 3 N 'SI 0% I hn . 6' i a ri . I'd Aa) I( 0% t3 £0 i 5 t 0 aw r-I ! 2aO- i U i .' IC CN- 0 t-h j - I- V.-. 0 - __ u_1 L 0+ H I,, w H Wu 418 I Lu t~~~~~,, T uI I---. I Jr- r M-f 1t Is I I m i i ! 0 i -- iN m le a% V- 5 log 10S , *m m w t a _ I_ es v 6 f .( a -Z s _0 4 NI,) '0 ! I l m4 6 6 , . !t; t -__ - S - I i k.) H I i S a i I _ o0 G.- i I I inC N 0 %N 0 o a 6 . 9 IE to N %a m 0 ON A__w A Pb 0 0lW I n 1'1 0i ' 0 I', oa .,U) r" I Q ,.J 11.1 .r 0 9 0. %6, _ 6 f 3) 1'- _% 00n N I i 1. le I' . m I1l11 a . -_ T- Ut 0m I UC C4 45 , j ~4 A r- C._ i II_14 z o _ _ . U) 9 ..-T_ : V U o I t 9 P 'A (A I I J t--0. iN -T i 1w9 ,,Ž uj ' 0 E~ U) zIm H E-4 -- I1 °.i 011 . R . _ 1-- I-- J cn DQ E t- U) I o a 4% .r 4v 416 'V 6 Oo go. 14 ; & 1 O6- 4D 0 ' o o 11 - ~ I-. N 0 o o oe0n w I 0(S6 _ Ts 16 o R Ib i_.--___ l~. U' a* I t a .* I . I A 1s 6 ty- 03 to r-Q q63 %S I.- _s u 3 0 -L AQ> C) I _ CD Q 0o e4 .9 .... _ a G | t~~~~~~ 0 9 PR 9i 0 0 ei . _ _.____- 'IZ n 0 Cy% 0 0 0 c' +._.._ EN 0 L(q r 0 _..l .... + ._ to - I E4~ IL 'T Iw ._ 00 0 ___ _ U' H 2 0 0(' V4 V. O -I;. +- n I . o S:I F__...____",_, '3 0 4 0 & O (I --z 0 + ,4 . 0 8. l (% 0. t-_ ____.___ 0 a] - : r b 419 9i '-4 H wU U LI I( UO | i I EU - - - - - S , -I --- IUI¢ lu l P ,1 I I i I I I 0 CO I I i t w H P4 rT3 I- I I 1-, f ,0 4' I I 0 ri H E~ 0- qr 'is 1.) ! l . _ . .r_ ____ ._ ,~+ ,*____ I I l I t ..e °...,.. . - 2 .. i- 01 -S S Ir 40 Io4 1* -_ L4. 1) I.. I zZ !,) . . a.. . .r z U) _. 4-' o '0 a . 4 .. r._^ ............. s- U 0 s - I -202 L I I r( U) _ _" _._4 _ _.. 9 ____ .......... | ___._ - _ IA 1D I '+ .1 0 0 . . .~ _..... 0 to _: -Z. f *v --- F--t- C4 00 1dz - __ ... s Itd ! v L LLI .. - o 0 _ _t V 2 o Co It. o0 U 7 o ccl co Oj - o o 1' 0-. o -_._ _ ( _. o t .. _ .. 10 %a - . |__fi o4 ____w_ rw- _ I 4 *-_H C;. to ._o_._ ... 0 6 A . .___._t _____ _ _._ __s m* ___ _ * CD ... #4 0'- m Ii U1 w 2 .__4 ____ to . . . o 1 - o. 0 0 0 . ._. . ._. t_ 49 I'I __ 7 .j. U 83 v-'?^ L , an .3 W-. '-9 a 0 C4 '.9 ~0 oo oo -0 0?- 8- %a q I i (S N 0 -co- 01 c co C . 0I X L, . 0~9: z m 0 L N U) 03 W 04 CD _ _ c .C VI .__ 10. z >4 ^_ . I U) U0 = T | t o I I C;i; _ ; 6 i . %. 14 I __ I q-o~ I A___ I I v' O I ( --- U) PN . I I LAj ._...._..M........... . 420 LU ..%... ..... , - - --.'IL- K - r I ......... ~L M r I --I -- I w . , - --' I I 0 1-.$. 1 N r i U) . I ~ UH C) 1. Q . f %f .) I Bulk$ - I "I if W ri 6 'd _ U) . I _ w _ . . _ . _ 1 Io' _ -. .. co [- o . _ _e,-o N iN _ _ 1 P I0 I I '4 a Cl) E-4 0 C? 0 I ON 0 ; U 'I I i ~ -4- _ _. I? I'w¢ ,~ .(I zz z E-4 ccb 15 4*3 0U) 0 0 0 . . U) 0 la8 i 0n0 (n U _ e4 _ II2 _ H H -7 o t16 0 % 0 ~- - IJ I o lszlg I ,,Q e 41, r H Ezi - £0 m i 1161C IC U 0 220 0r . N 's 6 .___._ . W . 0 0 m 6 0 10 __ .v %) 4_ 6q .:. P 4.) V) u 4-) g vi > Nt E-( 0 & d .N 0 O 9i q_) CD W: ZO 02 1x 6 r._. *. V n 4- Z: U) W CIe I _ upt A ',9 - I- 0 g d0 0 1(4 T .. 1IC - 1~ ,3 o -L ' 01 Z 0 tt It w U.L ul 421 i 0 - - a 0 __s- ___.S__ C z me } 0 1 _1 4 ON .1 _ _ I .y.I_ _ 0 a fJ Fse ' z o _ ._ . | U o 0 10 i O 'S 0 4 O r. N A-. {ram_ m,1___ 40° t, Ic 'C' _ _ _ !- I NE E-4 , 6 d A dA t0 if Uh C) 4F Cs . o o m,_lmIwW.,. 0 Qa 19 I r,P_ I- f- U -I ,0 Q i'Iti i I4 a9 i to o 19 I _0 0 t.4 N 10fc $ u.0 ,. I v 0 a 6 M to a N 11 %J Hol 'O 9. I Q0 0 0 a rqs- 0 6 '4 x (n 10 I4 is M I r 0 C) H I I 4-) *1: f eC .__ . le , id cv 0 ,J Z>t 0 M E 8 __ --. r 0 ;Q, 6 r .4 +Y 9 5 I, 00 yO .3 d tC) ' o 0 0 U) U r74 ) 3 H I" z ' I'll ). t0: 'd - q w__._ 0 o 0 0 _0 0 0 %3 _ 1t. If) I 9 CO 0 1I% I , I o 0 t- a'~\ CI It~ I 0 'I -0 cca W No Ito. Iu i o1 0 HQ. Ic LU I LH0U 422 1L 6_1) 0! 14 Il ^ 4 %90 L W : H 14 a- cO I " I f4 ol . : . ) [ II 6 f) >l3 0 0 L 1- of L- 0 a O 0 P C' 0 cn> C,0 OA It F 1-- 0 M 'C3 | _ _ _r 0 - - I4 0 0 0 414 o- *' 14- 0 "'a 0 u _ it' _ .1 0 - O M .ft . .? 0 Z! -.. d 16 ..,,.,. _^ _ F ; G* c. D 0a g o1 lo0 I:t3 6 c _r * I cv i II o,t 'S 00 II b d 0__ ? I (4, la_ 'A. I"4 fty I . I I ,we qrdr_" 0 I! 0 I* S _S t I U,. W U) -T- - - - - - . f 6 r'0 I. CN 0 a 0 %6- 4- III 6V - 43 w H 6VW I En Z2A~ . . I4 0 '3- r~i 14, , 4-1 I --. i V o Ia 0 0 'i rI 0 pi -soa "I -40 0 0q 0 0 = a.' 0% 4 CM I,; . tQ W 'SK ,o . ) -,'b", b . .I I 0z (I) i __ : r ¢x .H En I- 0 0. o U' eO , 90 E 10 U] 4) 9 o0 0 o _ _. . .......... ^ 09 t (- A. 116 3 1% 6o h- 0 ______. __ I o N 6 U 116 1 E In i,, .0 lj >11 E, tp'o.. . t. . c ^_ _ ' 5 o .... ._9 . _ .. i U) 0 .. )o H --. ---- U) U) W 0 U' 0 O E>4 .S - o. 0 q,. t4' b _. ... _. 9'6 0* 4- 1t (' c', 0 q~ . _ *.. .. e c A 0 . ... ,0o 4- 2 o * j o I _CO a b C 0 - 0 _ I .' N 'j5 X-0 IA 0 --I U) E-4 00 I& tZ i 3 . _3 _ 4, I I ~i 4% ¢- 6o 0 W E- 9 o H. ,¢\e_ 4- 0 ' (. 0 49 .d I C I i 6 ci _ a 1Il i La O~ 423 _ o0 i. I 11 2 1 Eq 1I ;P 0 o U) I k4.i *t . lb I I g' I ; I X,~~~~~~~~~~~~~~~~~ I" In4- 0U) z !; 0 i !* IQ I -41, II 5} ki o i 0 Q U) : w i c zH II 3 E-4 Z- t,-4 t IgO I )o i LA -- l _. .. 8 i U) U -4 it za ,,-.i 9 rw . U) . _ <_ _ _ I? _ . _ m r6 '41 I %) tt I .Ww s:r Ii ':3 s^ G 4 t , _ H .L q6 i . f E z0U) iZo r- . 0 )o -.,' N' i i i a . U) CD O U) b; T. V ... U} 0 cn E-4 . .... 0 C' C'j Un 0 C' i. o 0 u . I i B: ,~ 9 c1;0 0' "' ..I ... <. ¢,U U V 424 '4 SUMMARY OF TEST DATA FROM CKoU TESTS ON SHANSEP NORTHAMPTON SAMPLES 425 - - - W of 10 I t i I I i 3 p O; 0 -111%14 N v- 10 01 0, 4 q., f'- c6 t .° t___ - e _ t_ 0 t IA 06 z 5c! U P4 U UO EU Io 5 c-+ : V ) I 16 9A N N 10 - 0 o N -a14J 4o - a4 W iM ir .14 7 _ : I~Oo _ o t0 . %) v) 0 cr %A 6~ Cv co 6 6 Ln l I ce 0) I .6 '9 ce 10 C- u0 I IQ 1- W. 2 L~v 426 JI I sfl 40 It 4..01 0 04 .0 Ioq I - 6 I N l O 6 0uz 0 0 r l ' '9 W N IA C.' 4 P4 U d 6 V-' I , E 14)>ot 0 r-- ,IA --. i '89 6 (5oQ 6 6 O t r- 0 _6 0 or - Is0 ci4 0 '50 8 - c4 6 ao fi xD0 ' u (A __- .4_ Cl) ':3 Q0 >.' I 0i (I" I ._ 0- t t0 0 0 0 6 '4. V 11 to la 0 u) tf- }5 I. . _ I Z Z W U) __ 1 I ___ 1 I I 0 109¢ lv~$ r "I- '. az_._.8_. t 4 4 - I U.0 I I a0 I ce I" I N s 0 fn m id, I 1+ Q >4 0 z0 I i o 0 0 IC) 16t I i O 6-1 4i I in 0 O . 0 Id, 0. 4 ci k L2 0_ ___ . _ - -" - . I i - w 0 CA & ,CA b\J 'S o1 i^ ai _?m - l 0% #)I A e4 . 0 -(Vt I tA, N 0 0 v~ 6 0 0 0 4 . I (N W I~ I i$ v1 r 1 ,wr .1 a e SN 0 0tA N 0b _ i4 _, Q m - 6 6_ 6_ 02 _7. I - o 0r zX E- r .. O : 0 leto -9%ftj-'"6 6- I? - o 16 ,y W - '6 6 1,6 " ., t- f- r:. !n W 10 do i!Q ! 0 0 '19 %9I 6 6 0% t f-*0 o 66 6. z U] I. - --,,. , *{ 4' Ui _ 4 rz ,-.,.,,I| .... u z 00 m--...--.--I 1 U) 2 ..- w. '.4 b - - I r- on 0D61 .. . -Z, . -o i I _ 0o o, vg 0 i0'0 o t0 o C' __ e _ 0 0 "9 0,, d . - fl A in I. 427 ----- 0-- I. .O. r £ 'a 8 N In .0-- to - .- I w ____ N - + F...._ N VI- 8 _. 8 L . (A ; Li j -4- %n s__ _- P -H 0 o i!9 I U -Z .xt oJ _ U) U) .i_ _. f- C' CO 0% , ..-_,.- 4.) U) W (5 T6 1° ii_ 0 3 tj .tv ± a 0 C i6 O i Z '4 18 6.4 0 mb ? . 6 66: eto J_* 0 0 qtiJ i4 0 ;t f%g _I % &.° .... wq_,4 _W in . ' as t9 9 6 to - : AL I ._, ._ . !o 0 .113IN , lO w *N 1 0 g _; , t* i It _ (I; 0 I, *Q ... . . .r\, . 04 0 W o, _ 0o 6 d 6O ol 'O 60 - -- - fo 0 = _ 0 o 0o po .. E T T 4 ~0 co -IF xCs u .2 o D 6a 04 4J 'U I 1- _ _ o ,i 19 iwl 'a Y o Jo, IS .%6 T- i6 6 ,% - J . - gw~ I v,& Zq _ .JL 16 X £ !l t , 16 .a 1 p, -I as 0 I i I to Ito !II.-- - 0 6 c) ! m . I> '4-v i 4 b t IT y --1-----' £ :> 4 U g *4 6 0H % 1 0 f U: 0z 4. 0 6 I* t, I I 0 f 17% "-! i -a in 6 0 0cI 0 I 1 10, 1 (5 Ir - 0 H (U 0 0 E- V) IL t-i0 I co I od i 4 D '4 C"' i 0 0 Ito 0 0 8 8 0 -a 5 ELI U 0 0 0 0 H ::r ) 0 4 0 It Ide en U 0U) E-4 0 I U) 04 IoIn tA 01 Iws.. oo3 H7 L I " C.) AOA U t. ci 't* a - cJ .i^.. .. 1s vt L 01 U. 70 4IA 4(.0- I- N Dn a z Q Z F.^...,.. In C | ... W_. to S oe 1IZ _._ V Z __ 428 "' z CO 4.. - o r Z 0. "-9 -- 0 Dcm CL A CO Z L d) z SUMMARY OF TEST DATA FROM HACKENSACK VALLEY VARVED CLAY 429 -- I 0 l - M- II - - - - I 0 6 6 a N lo 6 P4 E kU~. U co L 4% -; 0 0n 16 0 zUt E ) 14~' It 6 6 U) __ n aI I-G __ .... 0 N · ___ . cr '9 12C4 ! !tv% , o Co v v, En co nr -b . -- 1* I v 0 l U) '9 0,D E 0 1 1 01 ___£... 6 1 0 6 I I ,c 0 O' O 4-j _ ON 4 -ec 9O .k" -.1.9 c- ko 6 6, t o v- 6 o,65 oe a '. io 6 6o CO !° io LA 0 k-j L-1 j jI uP. t--1 0 c6~ . __ > . . _,I .,, o0 ... U 0; oz > U> OU t 0 10 . A U . _ a aV . I I 'a 4 O 0 O , U ,v_ o 10 . -y ' v 4t I '4' % xn 0 .I_ _ O O · _. 0 tr o V U o' O I __ -J O o .. Nt 0 k. j3 U 0 0 0 > 44 X I I. . CO Li' 6 6 I6 a F) 'n I t4 7' -4- S 430 I _ : n 6C) ,¢ ,._ _ 0 I I r- F-s - '9 -. __ Ez U) V v , 0 's 4J 0 -C!d ID 0 i o0~ so 0 I im 12 n IV z 0z I= !O - . %.9%s Iq k t---' 0Fi . l '4 10 _ ._ i1. j I0 t 0N Q ,6 6cX 0 I O b ..... i 0A -7 fi V APPENDIX D TABULATION OF TEST DATA Consolidated undrained strength test data from Amherst and East Windsor varved clays are tabulated in Sections D.1 and D.2. Strength data from Northampton varved clay were presented in Lacasse et al. (1972). Saxena et al. (1974) presented the test data from Hackensack Valley varved clay. The organization of the tabulated test data is as follows: Section D.1-l: Tabulation of Test Data from CIUC and CIUE Tests on NC SHANSEP Amherst Samples Section D.1-2: Tabulation of Test Data from CK UC and CKoUE Tests on NC and OC SHINSEP Amherst Samples Section D.1-3: Tabulation of Test Data from CKoUDSS Tests on NC and OC SHANSEP AND RECOMPRESSION Amherst Samples Section D.2-1: Tabulation of Test Data from CIUC and CIUE Tests on NC and OC SHANSEP East Windsor Samples Section D.2-2: Tabulation of Test Data from CKoUC and CK0 UE Tests on NC and OC SHANSEP East Windsor Samples Section D.2-3: Tabulation of Test Data from CKoUC, CIUC, and CKoUE Tests on RECOMPRESSION East Windsor Samples Section D.2-4: Tabulation of Test Data from CK UDSS Tests on Vertical East Windsor amples Section D.2-5: Tabulation of Test Data from CKoUDSS Tests on Inclined East Windsor Samples 431 SECTION D.1-1 TABULATION OF TEST DATA FROM CIUC AND CIUE TESTS ON NC SHANSEP AMHERST SAMPLES 432 7 w fa I- 4 z a a1 t- 0 Uo ,ob 0 o- i 0 - .WJ w Z .. t F ' ~ o b' E 'A I i flo 4 :)U) - v), 0. 4 w a 4 U sn . # -- to LSA;0200%A odd 66'66 66~*' '~~~~~~~~~~~~~I M! b~~I-n 6 6 6 to C *lI _I .- Ag o' IOnu .. a: <1 ai| 'O~ 66564 I n |N b- k I .in le~ C ?' -~-'m---'-=0% 666 - 4-'-: . 1- m a Tiw z ~ I v -iE a ~~~~ . - U IL a Li z 40. Ax 'S 4n -@1 4-. ':'- ~ 0 oq -4 ,4 0W 0 :) -C o Oo -j U 2 U -, w - l- I 0 0~~~~ W W ac Ii 0IL 44414 l I 1a 44 414 4 00 1 -A.iO - 0xW B B- 0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~, . ir 0 U, ( N.~~( 0666 I- 4 I. , ~qt% 0 ~~~~~~~~~ IV an z02 n o - o U; m 12 0 I,/ 0 v) LU) (I) z B- VY an a- - -- co- - V) F B.- I- - K. w a 0% It - * I w I.-. I l _ _j4O 61J1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ · L__ A O__ o OOOe 4 OOfod4 0 0_0 -C I w p0i.ttkt; 6______T l-- A 0 C e 31 4z ::RIA a H 131 wt4l U) w I0- 4 400 '4- 2an a ,,,, . "'.: ,G 0 ~ t, . I o * v) ). v)V co a- 10 4: 4 -4F- 4:- IlC 0 a aw .I w-, 0 a: B) I- U) 49 I'"I 1. 433' v 0B-c 0 0 4 04 o f04lot tt7M i~~~~~~~~~~~~~~~v 0 I- (1) I Iz I a: a \ t 0 0-J C F x w w 4C1 I.0 0 -j E~~~~~~~~~~ ~ ,~'6 °d6 oo66666,OOO0 -T o 6OO ,66 0 () -X o -tt OE6 L66o VoO G66Q 9 Li I: 4 w x . c - w cn 4 0 . g la I a. I| 00 Z I CO (If 1 -4 z 4 KN E 2 ir _o ,a: 4~ Z) o -T ll;I lb cw a: I IN 3 "a' NN tCV N j~~~~c I- i 'O I z w O 4 a a: a. I- 0 . 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IQ Lz t4 I t* 6 (Jiltr 10 I 0 rJ~ ~ 5- Ia W f Wf f~ .1X ~~~ 0 oo6 3 I 0I 0 ! 1 S: * p 0 0 00, 0 Z c " c o60666 o i~id s~ .... . a - .;:-66<6o .r=.Jgo 1 i g 0.!!1-.0 , ~, oo, , '4'- ~ ' -~~~~ a W- U) 0) , Z 0 U) SM 2- O~~~~~~~~~~~~~~~~~~~~~~~~ N A06 ""~ - W 01 -____T4 --- ~~~~~~~~~~~~~~~~~~~~~~l.~ a: 2 0 0 Z aU. In ¢ SM 4 It - I 441~' ~0 414 I4 I4 Il4 WI 40 I- SM . r- p W x W 0 (J U *1 -1 lms b. Ie VP T' · . -Wc. -54 144 JE oZ Cc IU, J - O 0 U. 0 aSM0 owW Ia .I a t; 0 J b4 5.- U or oi 0 < , El I w a U) I- " i U) 0 z a a- o' t W z o 0 1- r 0 MoX: . ,,I , J t. U) -n 4 cr E VI'l w 0 o z-i o U) a. C U) z0 ) I I - >- 0 § U)191% 0- Id on U) W - a ,- U) ajg.K 0 _ J -J >?:IU1t C, U a0 Z - I - 4 ' :E o X U ocr I. ta 0 o: x 414414 4114 i 4 4 O C) 0 Jm at c o Q -jI 4 4 0 - or 0 LI t, - 2} J 0 JIi w C)0U U) r 0 . C 4 0w o 4 o SECTION D.1-2 TABULATION OF TEST DATA FROM CK UC AND CK UE TESTS ON NCOC ANDSHANSEP AMHERST SAMPLES ON NC AND OC SHANSEP 438 AMHERST SAMPLES I ~ In a: In 1- Wh N Z -: 4I? a: Z -4 -- 66~ 666o8~6 ae6 I 6 0 66~66e\0a ,0 Lo 6 to ?oo~toaoEo -6m66~6~6- -- a5,0660 ac 4x Z 660 ~ - ~ 606o -~Q~~ I - i 10 -J 0 I I- I- Z 0 U 0 -j >_ 4. a-| B.' 4 cc $10 °z a I 3 ae i i.O _! 2*- In I I. n- Z) t U)b 16b T 4I) 4j Z Wz A _ ,to -O O 01 -:- - -6cS U) X a: 0 0 laj4 E cr (66LOOQ6O6OOO0 ,_r Wu E Z f. lb--ft? Z w W - lb C~ C. I ' cr~~~~~~~ o 0 V) - .,t .3 .I c-ii 11!0 A t) w U. 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SECTION D.1-3 TABULATION OF TEST DATA FROM CKoUDSS TESTS ON NC AND OC SHANSEP AND RECOMPRESSION SAMPLES 447 AMHERST Sheet I of 2 DIRECT - SIMPLE . w_ __ . ,PROJFCT 01.L SOIL TYPE vNARuA cLA-. TESTED TYPE ; ~AHPLE_ I Initial | e I w ,/' 64,1 I I.,2q-5 Th | STRAIN (Hr.) (%) vc o0 o 0Q& o L45 S o o03 tq.of q·- L1 0.3Z qj 0&. ,og~ | 0,53 ( |-- |O.1;1 | S to 2. _ __ 4 l. _ _ i O.V t1 | o sZo.gO. | |.136f 0,111 0.Th1 o.t S5 I o..4. . C. tzt 2|-5- o.Suq l o.I e.1 . 7 o..436 O.' O-.. 1o i e_ _ _ _ _ _ _ _ _ _O _ _,12_ __ O 1... 0.| Ot-64 O,t>1, . . . . . . . . . _ . . . . _-- _ |. _ .Z65 0.27 .1 O, I_ 1 ... IS I .2 .. _.5__q _ | I, .I . . ,__0_ o.Sf . __ O.o o .6 o6z22. . I o.i2 53. . . . e.257 .| ..... G.55 _ _ _ _ _. . . . . _ 511 oAq C|121 0 6.q | _ _ _ O. | _ _ _ ... |_ o._oqo CiS 05 S 03] | 01 .07 9__ _ _ _ _ 0. |g o. 34 |O36. cq Qh 0. 0 T o QL2 014 o. 7q 0.30 .l; _, 0'z¢1' 0O.253 Ovm _ _ 0 $$sg o.-55 ; 106, 0 ~qSik l i ~ ioqq 0-g ._. 10.{70 A1Q.o o.it 1 '6.03 O |.oZ, 0 1,' o 0.q 0.2_5 0. 22q 1o. vm 0-qi'1 iTS 6.5REMARKS vc .oooi Lso Io16q ______ | Stress Th O t_ |D o I Rate N. / Hr.) .ozS .45 0.150 | . . DURING SHEAR 96 9 0.074 - O~o51t O~~~~..Qc O.q~q | o.tz 5 33 _ \,: '0 I | 3 2o | vc 0,31s , 2. ) V .oq. 9 2.13 ____ ~oOO. 0113 | -; 1.33 IIb q. I3 O.- o. Ooq' , Lq-44 1.01 _Ie: 1 Q0 q..L o~cl' S 0 ci:~ .cSG o~ L5I J.. c.057 o .21 LIq,{5-oL|____COt Lq. MG j | 7Ovm /o)c(%)-tc(Day) o.glQ o. 13q uL I 0.0 ~~~1L~ L.tj 3~~~±L I 1 -- ! l.o in K4) Controlled Strain/ 4s.e TIME | H ( - OCR DATE_/6L Thc 37 Presheor Final (Stresses 4C ° S,% NO.A5 I DEVICE tc(Day) , TEstN: AP I BY fLV.. -v U-~ . CV-cU CONSOLIDATION LOCATIONHcsT SAC.4 P OF TEST SHEAR TEST L O,3 1 C3z_ I '. %%..I SOIL MECHANICS LABORATORY DEPT. OF CIVIL ENGINEERING MASSACHUSETTS INSTITUTE OF TECHNOLOGY 448 t _|______|____ . -7 _ I . REMARKS: _ I _ I Sheet 2 of 2 DIRECT - SIMPLE SOIL eMWERstv Rtct PROJECT e60A STRAIN (%) TIME (Hr.) i.155 13 _ .3Z 846 _ 1.q O.?q3 O, Ig 0.50 oti v 0 )547 13o{ ,5' .. Q9:.ttL O ~to5qt IL2.6Z3I p.iS3 o 12-.. _____.__ .__ o .i. _ , 12q .3_3 O ms5 - 0.3. 0. 1 4 o.Z15 o.kOo O.li- 0.125 , _q _ _ O0o o.y 3 4_________ _ msa~v .0O oo o.31 ouIlq . _ ,, 0./4q o.6%3 2qc. _ _ O 377.... O. . oa.__ o.C 8 0 106 REMARKSvm 'vm _______; o. o. 27 I 0 351 .... O~l 6 o.o .3(0 26.Ls , _1. qs ° _ 040h .57 4L -,m 0_4_ 0 o.6 . .5St Elj2W NO. Ds rh Iv O'v s0o ,oi5; i 61 iq.qq vc LdC o.13c. 0.564 I'. 3Z ,._164 _ T.h -(vC '"v e.0 OF TEST ETYPE Au IV.~2. _ SHEAR (continued) _ ___________ .... ...... __ _______ .... ~~~~~~~~~~~~~~~~~~.... _- ~~~. .. -~~ SOIL DEPT. , ~ ~~~ LABORATORY MECHANICS OF CIVIL ENGINEERING MASSACHUSETTS INSTITUTE ~~~~~~~ .... , , REMARKS: OF TECHNOLOGY 449 ~~~~~~~~~_ Sheet I of 2 DIRECT - SIMPLE $801f. PROJECT · SOIL TYPE TYPE OF TEST ct-y vearRt TESTED I e t78 . Preshear Final 53.0 TIME (Hr.) STRAiN (%) ''.q) .03 S ,%/ . 453 Th vc c v O-io O.o65' o. c2 O 9S 0_o_$ o.o' o0to5 012. . 1 o.Sq O.cS3 c 0-O4qq O.304 C.So . oo __ O. ti2; 2.co I.go e0 3.. 3.51 .13q Ot .30 6._4_ _q.2Z. 0. _ 6 O 0. o. 1q X~S SOIL MECHANICS DEPT. OF CIVIL MASSACHUSETTS O Iti2 O. 02 &"_ O0>5, . .q O ic I.Q 06 0, ' _ o q3 . .o o. 122 O.6qS 0 61 0.21 _ .s ~a .0 O.66 O. 05'1 )6.~ 4 0.5f0 o.2ql 0.5,9_ 0._______ ot -7.0 S - 0 11 0.1_q o.21 7 _ 0,$27. ,5 o.52. 'vm 0 o q5 slq Os o'2o. > 22.1 130 REMARKS - _____ O_. o. Do.b4o O..5 L .q . 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(/) ~~~ vc C 2 REMARKS h 7vm 'v NO. zvm REMARKS o . .'_0_q O.ssQ ,5__ Iq _:_j . -01565..0,5s? 0,41 I1.O3 _ I .2 C.153 0 o. ti1 0.5-3 _._35 7 a. 4_i L D.t-1 _ o_X.4l- __ _. to _ _tO09 O.l Zt, , Li6 '.Ogi 0 2 (,,. ~o Zl.f56 tS.$1 0 o 3.i 0 i4 Q lL C.3 0, 376 0,% h .3 -6o 0.360 ObS5 0 5~7 0 ..x0 o-611 _0.$ D. 116 .1i6 .. _ __, _ .}~ ,o 0.653 O.I0o.1oi MASSACHUSETTS . 5- o0125 3,~o 0 0.3$7 ,,,:,,~3ZO, .3G;S OI 38 2IQ. _ 0...6 . e6 h ZZ,. 55 3O.'06 ( _.. , I1h . D.329 0, 39$ 0.316 0.2qq O.34 C 7 4 Z0t2G 0. w3 C4l2 O-%q$ OF451TECHNOLOGY INSTITUTE .... , ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. .,... . ~ ~~~~~~~~~~~~~,, ., SOILL SOI DEPT. MECHANICS LABORATORY LABORATORY M ECHANICS OF CIVIL ENGINEERING D EPT. OF C IVI L MASS AC HU SE T TS . REMARKS: REMARKS. ENGI NE ERlING I NSTITUT E Of TEC HNOLOGY 451 Sheet I of 2 DIRECTPROJECT 8Ol9Z. SOIL TYPE tAEb LOCATION I ADAINc, TESTED C,=Y ADS- 3 (Ctecom"PcroiGN) I1 I Initial C7.7 Preshear 635 .6 i 5 STRAIN (Hr.) rh (%/) ZL oOq 0.057 0 ._ _ :-O 19____ |_ ____ _ ~050 0..oq _ __ _ _ 'vc 5.- h RE MARKS 'v 'vm O.qS O o'lZ 0.q2 s oq4 . 'vm o.o .o.o . | O I o0.65 0. I 0.120 0156 0. 23S 1.20 0.165 o.2b6 D. ll o, nS Q 11cl .2. ?l o. ~~.0 0tql 0, JqL .L O. | O. ISO . 2.0o 07 ' _ _.oI, _ o. 37 ;oq .51 o tq O. I 0?zo 5.5, o o.zoo 0, 9 DO4S D j7 O 0436 0.460 O2oi,, O 23, o70 0.12 o.Zs O-0 O.16q 0.6% 0. 21 | | _St__ 0. 13q |) 093qb 0 .p._121 0, 0.7.7 0 .l~Zl 0 ,w7 o0 0 lo o.oQ [ | o.1-c ,-l -S G7 . . 62q7 I_ o,_. 0491 v 35 1l 0.571 _ o.z49 0 o 35. |_ .56q 0,53i . . L _ _ _ _ _ _. ,.Iq . I _o._ 0.0 o'3 , I 5s . e 01055 o. 691. |, __q_ t3 o.2'1~5 o.0. iqzc !!.0O O ci? 9 | oq9 o O, O.f. . eS 8 c O.9S_ 6.26 _ |r |. Stress i5 D 111 6.5i o _ | __I |-~ ~~hO o , 2 51 l _ (%/ Hr.) Rate p).150 2 01S2 2.5 i L DURING SHEAR Controlled Stroin 5 0.16 i .140f.o2 o. ISo _______ ) 0.1 G _ _ _ .50 _____l T rhc ' vm Ev(1o) _'c(%)tc(Day) .q 00 g, iz 0.20 o.oq5 : Wq. tG ' o.oy o_0 0_15d __ il, /,) ,_o.i , 00. .i1 .T_ 3.0 _0, o.6 S6'Q 75 ,,_ .6 7.26 _I~.,|e. .'i) 1'9 Q. 'Y0 05 0 00 to _l L vc _vc 0.o5 q. qq in DATE 7/~3/23 I.I H ( i qi Final TIME I .- e /o ! , (Stresses S OCR /,G6 DEVICE F.Li-i 'avc ic(Day) E W BY ] 53 NO.A C VoU CONSOLIDATION 6 -7, SA LS- 3 SHEAR TEST TYPE __ . ._ _ . TT ., __ OF Ath'-eRSr W~ ! W WV V~ W SIMPLE __q_ .. °_ __ ! 0.38' _ _ L _ _ _ SOIL MECHANICS LABO R A TOR Y DEPT. OF CIVIL ENGINEERING INSTITUTE OF TECHNOLOGY MASSACHUSETTS 452 _ _ _ _ _ _ _ REMARKS: _ _ _ _ _ _ _ _ _ _ _ _ Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE SOIL R~s~ PROJECT TIME (Hr.) rh u v --~'C 7v -cvC STRAIN (%) vfRweorL84TYPE OF TEST .C (va rh a, vc °'vC h zv °'v _M 0.(qM q ,g2 o.qL D.. S.s,:. o.s1z 0.510 o.q11 0 40o Io: n. iqz 0 -56 0._11 11.S52 b. tc I3 0 o.1sq 15..o5 I1' . 0 so 0.562 .s o. o,1 0.O_ O.13i o_ o..'ss oJ53, S2.Ss5 t3 I5t 4 23 80 l/ '.0S 13SS O.63 . _._ _I, _ _ _ 0.I106 0.29l4 .1q .1?q 0.21i o. 21 __._ C.i25 l 0917 ,. e . .755 o..L, 0.7i O.727 0 52L 27?.6 133. o tq .T0R .7 0_ _30.6 _. 0. 2 1t _ Q13q 26I 02. _ _ . _ _ _5_,' _23 ' o5?q :_.59¾ ., _O _ .. _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SOIL DEPT. _ 03_ Q._46, Q [31 2 6.3o REMARKS Rvm °~'vm O1 156 O.3 .6s_ .o.5 o-5-o Ib40 . ,, ,.. LABORATORY MECHANICS OF CIVIL ENGINEERING MASSACHUSETTS INSTITUTE REMARKS: OF TECHNOLOGY 453 3 = $.0z _ vvm NO. Sheet I of 2 SHEAR TEST DIRECT - SIMPLE PROJECT TYPE SOIL TYPE v!eab ct-i TESTED LOCATION. tepsr CONSOLIDATION (Stresses I V V-- ~ J I V OF TEST BY CA F DEVICE D.L 3 o .OCR I/3213 DATE in i/) WV Pe hNA --SAWLE f-2 Initial S,% H ( ) 0osqn I sk1L TIME STRAIN rh ( Hr. ) (%) O'vc 2. oszL . O_.to, 0 157 [. US 0.522 O1i IoL, _.43 oeot o..os 02. , -. o .040c _ - oe 2 . --D.06 _0.073 O10I7 oIS2 -p0O3 Oo 0 .0%z - 0. e).z4 -~ g!i26 l l26 8.274 - 0. O. 0.- 06 - .I 0.Zff O, p.Z? . IJ26' .I143 o14 . \5O qI .t I 0.32 7 0-35. *-o.lgl 0.3L -O. 0 NO 014 S I,1l 0o4. Go.2 O, 1 3 o. 0 -o t3 SOIL MECHANICS DEPT. OF CIVIL MASSACHUSETTS -0o. 09 . -8. 06 o 30q lqq Jj O.ij o o. I,DI O -2 tc0 o _ _ . aclq,3? 0 _, 4i _L D9 D.c 0 41iZ 0. C' l ___ _ I _ O 1_- ___ O'S pj-i8 LABORATORY REMARKS: ENGINEERING INSTITUTE OF TECHNOLOGY 454 Z _ Lit.z D 14 O _ _ _ 0.t_ 9 _ Da340 t08q o.no O-Y' o%. 0,3%1 O.2q0 .tq i o. 0(i O. o-1C' I,% O. 0 - o. nq q _ 1t19_ I f. i'01 3 z eO.356 l 0 i. o-3 .3 A31 0 17_ -O, oi g 3 . _.-_ _ 0.%. h.0% D q5 13, I Q 0.'0 C00L 0. 2 (- - o. ,l 0. 3IC% - O.iqm 1 q 6.14_____ o372. .o ........ o. O.SI 029 6.7G .o' O.0 t.Iql __&_ 03 .S.I O o.3z S Oo.0 o0a ? tij 1.04 ' 0.21 o,__ 0. i~C. , o7o3 ,06 I. Ii 3 I3 0O-oq 0I.Z 1.ofo o_ _o o1, -oIql 4.1 SS%, 5-1- LIo l o/.~ -o.o4 1.o4. 0,2 I . vm O__ o ,o O, i,0 3 L5 m .3 O o- 6 ©,ofq i.o31. i_57 v 1.. .___ _ o.2?6 - o. 0. 1 5. REMARKS 'vc c 000 OOO _O0, DURING SHEAR Controlled Strain v/ Stress AU 0 ' : 3.o tc(Day) C(%) Rate(%/Hr.) Final . 'vm /o) tc(Day) e Preshear Thc 1° '7vc U-& | _____ NO.A U __ Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE TIME iiursR-r ime SOIL PROJECT STRAIN rh (%) 7vc 08.3S o 386 (Hr.) vc -o.\l -o _q3'-o .0_.0 .-p. op. . 0 %AST - tit kO(, ,I~.sS ' oso 0.5%S .31S O6oo40 oo ______ . _._ 2._q 32.,l 5S .S O_. q1g . q31 1-1 io 9to, 0.35¥' e(.,'$ o. 56 1;so 0. W1L2 ± o,3 q1 o.0 16 0c.o, . r3; . 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Final in 9!,) ' ]) ) 0.939 Preshear DATE °I/3/73 Ev(*/o) _c(%)-tc(Day) I s ,% e 51.2 5q.2 6,0.O OCR DEVICE (Stresses tc(Day) I w. Init iaI BY F. .L CONSOLIDATION AP5- s. . NO.A 5 OF TEST. CK U o. 1 OC3 REMARKS: _ _2 Sheet 2 of 2 SHEAR (continued) DIRECT - SIMPLE PROJECT OF TEST SOIL a.tHEgsT vaeqE~D LYTYPE TIM E STRAIN (Hr.) (%) Au O<. -1v rh |rh NO. CVu ~c 0.5%9 O 5hS, -o~79 - 0.4,1q I q0q I.-1q O.3 ,5 O36 o.oq6 OOq? o.26 0.26 a.5z -o.q 7 Iq 1,hl . 1Ii4 0.373 Q 0.380 ...3 O.oj~ o..oo q o.sCZ 0 571 .%q6 - oq79l o,20 0.265 o. 263 _jq jq 0o.19 -. 1q7 I1,41q 03ql ko.440 o5sh -. ,qq I,4l8 O. g, - O.qt, q i 'qs O.%9q 2 S3 i',.s7 tq, ,z o.5 4 -o 19q '7. 3o '/.830 %.35'2 $.~1/1 O'v lq qsq tb JAIq lctl~z- gigO. 609-I-,IIIo.~oq -o.q~414~ }.... 17,23 5.~[ 0.6z 1-7.Z.3 - o.q6sc - j2 6q O (02t Z...4. IZ . 13 O.t6 t q 2s,z O.z552 .-- 2z6O.z gT/ 11 o.sCo lo.q,. o.,.,7z %1.37 _ o,4 sq 31.51 3 o36 twq4, . 3S. 60 7, 4 Q 26t O 06to t. 45 c.tM .2G O D. 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