vii TABLE OF CONTENTS CHAPTER TITLE DECLARATION ii DEDICATION iii ACKNOWLEDGMENTS iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES 2 xiiii LIST OF FIGURES xv LIST OF ABBREVIATIONS xx LIST OF SYMBOLS xxi LIST OF APPENDICES 1 PAGE xxvii INTRODUCTION 1 1.1 Background of the Study 1 1.2 Statement of the Problems 3 1.3 Objectives of the Study 5 1.4 Research Questions 5 1.5 Significance of the Study 6 1.6 Scope of the Study 7 1.7 Expected Outcomes 8 1.8 Limitations of the Study 9 1.9 Definition of Terms 10 LITERATURE REVEIW 11 2.1 11 Introduction viii 2.2 Slope Stability Analysis based on Limit Equilibrium Method 2.2.1 2.2.2 12 Two-Dimensional Limit Equilibrium Methods 14 2.2.1.1 Two-Dimensional Method of Slices 15 2.2.1.2 Common Methods of Slices 18 2.2.1.3 Two-Dimensional Methods of Slices 21 Three-Dimensional Limit Equilibrium Methods 24 2.2.2.1 Anagnosti’s Method 26 2.2.2.2 Baligh and Azzouz’s Method 27 2.2.2.3 Hovland’s Method 32 2.2.2.4 Chen and Chameau’s Method 33 2.2.2.5 Dennhardt and Forster’s Method 36 2.2.2.6 Leshchinsky, Baker and Silver’s Method 38 2.2.2.7 Ugai’s Method 39 2.2.2.8 Leshchinsky and Baker’s Method 42 2.2.2.9 Hungr’s Method 44 2.2.2.10 Gens, Hutchinson, and Cavounidis’ Method 46 2.2.2.11 Leshchinsky and Mullet’s Method 47 2.2.2.12 Xing’s Method 48 2.2.2.13 Hungr, Salgado, and Byrne’s Method 50 2.2.2.14 Leshchinsky and Huang’s Method 51 2.2.2.15 Cavounidis and Kalogeropoulos’ Method 53 2.2.2.16 Lam and Fredlund’s Method 54 2.2.2.17 Yamagami and Jiang’s Method 56 2.2.2.18 Huang and Tsai’s Method 58 2.2.2.19 Huang, Tsai, and Chen’s Method 60 2.2.2.20 Chen, Mi, Zhang, and Wang’s Method 62 2.2.2.21 Cheng and Yip’s Method 64 2.2.2.22 Zheng’s Method 67 ix 2.2.2.23 2.3 2.4 2.5 3 4 Sun, Zheng, and Jiang’s Method Critical Slip Surface 69 2.3.1 70 Finding the Critical Slip Surface Optimization Techniques 72 2.4.1 72 Global Optimization Techniques Summary and Discussion 76 RESEARCH METHODOLOGY 81 3.1 Introduction 81 3.2 Procedure of the Research 82 3.3 Data Sources 84 3.4 Instrumentation 84 DEVELOPMENT OF INNOVATED THREEDIMENSIONAL LIMIT EQUILIBRIUM ANALYSIS 86 4.1 Introduction 86 4.2 Initial Considerations on Slope Stability Analysis 89 4.2.1 Total and Effective Stresses 89 4.2.2 Tension Crack 91 4.2.3 Earthquake 92 4.2.4 Local Loads 93 4.2.5 Three-Dimensional Failure Mode 93 4.3 4.4 5 67 Three-Dimensional Equation of Factor of Safety 93 4.3.1 Directional Factor of Safety in X-Direction 100 4.3.2 Directional Factor of Safety in Y-Direction 103 4.3.3 Intercolumn Forces 106 4.3.4 Overall Factor of Safety 110 4.3.5 Determinacy of the Problem 111 4.3.6 Solving Process 112 4.3.7 Special Considerations 114 Summary and Discussion 114 APPLICATION OF PARTICLE SWARM OPTIMIZATION 117 x 5.1 Introduction 117 5.2 Parameters of Particle Swarm Optimization 118 5.3 Swarm of the Particle Swarm Optimization 121 5.3.1 Topology of the Swarm 122 5.3.2 Size of the Swarm 125 5.4 Termination Criteria 5.5 Application of Particle Swarm Optimization in Slope 5.6 6 Stability Analysis 126 5.5.1 Coding of the Particles 126 5.5.2 Fitness Function 128 5.5.3 Modification of Particle Swarm Optimization 129 Sensitivity Tests of Particle Swarm Optimization 130 5.6.1 Optimum Swarm Size 132 5.6.2 Optimum Coefficients of Velocity Equation 135 5.6.3 Optimum Inertia Weight of Velocity Equation 137 5.7 Solving Process 139 5.8 Summary 141 THREE-DIMENSIONAL SLOPE MODELLING 143 6.1 Introduction 143 6.2 Framework of the Code 144 6.2.1 Modelling Process 144 6.2.2 Optimization Process 148 6.2.3 Calculation of Three-Dimensional Factor of Safety 6.3 6.4 7 125 152 Testing of the Code 153 6.3.1 Calculation of Total Area 156 6.3.2 Calculation of Total Volume 157 6.3.3 Calculation of Total Weight 158 6.3.4 Discussion on the Value of Grid Width 159 Summary 161 VERIFICATION OF THE RESULTS AND VALIDATION OF THE COMPUTER PROGRAM 162 xi 7.1 Introduction 162 7.2 Verification of the Results 163 7.2.1 163 Problem 1 7.2.1.1 7.2.1.2 7.2.2 7.2.2.2 7.2.3.2 Results and Discussion of Problem 1 165 167 Geometry and Material Properties of Problem 2 168 Results and Discussion of Problem 2 169 175 Geometry and Material Properties of Problem 3 176 Results and Discussion of Problem 3 176 Problem 4 7.2.4.1 7.2.4.2 7.3 164 Problem 3 7.2.3.1 7.2.4 Problem 1 Problem 2 7.2.2.1 7.2.3 Geometry and Material Properties of 182 Geometry and Material Properties of Problem 3 182 Results and Discussion of Problem 4 183 Validation of the Computer Program 188 7.3.1 188 Case Study 1 7.3.1.1 Geometry and Material Properties of the Case Study 1 7.3.1.2 Results and Discussion of the Case Study 1 7.3.2 Case Study 2 7.3.2.1 199 200 Results and Discussion of the Case Study 2 8 192 Geometry and Material Properties of the Case Study 2 7.3.2.2 190 202 CONCLUSIONS AND RECOMMENDATIONS 206 8.1 Conclusions 206 8.2 Recommendations 210 xii REFERENCES 212 Appendices A-H 227-315 xiii LIST OF TABLES TABLE NO. 2.1 TITLE Available equations of typical 2D slope ( Fredlund and Krahn, 1977) 2.2 PAGE 17 Available unknowns of a typical slope ( Fredlund and Krahn, 1977) 17 2.3 Comparison of the most commonly used methods of slices 19 2.4 Components of moment and force equations in the methods of slices (Fredlund and Krahn, 1977) 22 2.5 Comparison of metaheuristic methods (Kitagawa et al., 2004) 75 2.6 Summary and characteristics of 3D limit equilibrium methods 77 4.1 Unknowns, equations and assumptions of the present method 111 5.1 Sample coded swarm of the current study 128 5.2 Properties of soil layers in sensitivity analysis 131 5.3 Results of the sensitivity analysis on swarm size 133 5.4 Relationship between coefficients of different tests 135 5.5 Inertia values of the sensitivity tests 137 6.1 Position of particles in a sample swarm 149 6.2 Results of the calculation analysis 154 7.1 Properties of soil of problem 1 (Huang et al., 2002) 164 7.2 Results of different studies for problem 1 165 7.3 Properties of layers in problem 2 (Xing, 1988a) 169 7.4 Properties of produced models in different tests 169 7.5 Overall results of analysis of problem 2 171 7.6 Comparison between 2D and 3D results of problem 2 173 7.7 Comparison between the results of 3D simplified methods for problem 2 174 xiv 7.8 Comparison between the results of 3D rigorous methods for problem 2 174 7.9 Properties of slope in problem 3 (Alkasawneh et al., 2008) 176 7.10 Minimum 3D FOS of problem 3 180 7.11 Properties of slope in problem 4 (Yamagami and Jiang, 1997) 183 7.12 Minimum 3D FOS of problem 4 186 7.13 Classification of soil layers in considered area of KUR (HCE, 2005) 7.14 191 Properties of access trenches of line 2 of KUR (DKPCE, 2005) 192 7.15 Properties of soil layers of case study 2 (Liew et al., 2003) 201 7.16 Groundwater level of case study 2 (Liew et al., 2003) 202 xv LIST OF FIGURES FIGURE NO. TITLE 2.1 Forces in the method of slices ( Fredlund and Krahn, 1977) 2.2 Forces acting on a thin vertical slice in Anagnosti’s method (Anagnosti, 1969) 2.3 16 26 The combined slip surfaces of Baligh and Azzouz’s method (Baligh and Azzouz, 1975) 2.4 PAGE 28 Slip surfaces of Azzouz and Baligh’s method including a) 2D and b) 3D problems (Azzouz and Baligh, 1983) 31 2.5 A typical column of Hovland’s method (Hovland, 1977) 32 2.6 The slip surface of Chen and Chameau’s method (Chen and Chameau, 1983) 2.7 Chen and Chameau’s method after applied assumptions (Chen and Chameau, 1983) 2.8 35 Three-dimensional problem of Dennhardt and Forster’s method (Dennhardt and Forster, 1985) 2.9 34 37 Three-dimensional model of Leshchinsky et al.’s method (Leshchinsky et al., 1985) 39 2.10 Three-dimensional slip surface of Ugai’s method (Ugai, 1985) 40 2.11 Developed model of method of slices by Ugai (Ugai, 1988) 41 2.12 Three-dimensional model of Leshchinsky and Baker’s method (Leshchinsky and Baker, 1986) 2.13 42 Three-dimensional model of Baker and Leshchinsky’s method (Baker and Leshchinsky, 1987) 43 2.14 Columns system of Hungr’s method (Hungr, 1987) 45 2.15 Three-dimensional slip surface of Gens et al.’s method (Gens et al., 1988) 46 xvi 2.16 Log-spiral failure mechanisms of Leshchinsky and Mullet (Leshchinsky and Mullet, 1988b) 48 2.17 Three-dimensional model of Xing’s method (Xing, 1988) 49 2.18 Assumed rotation axes in Hungr et al.’s method (Hungr et al., 1989) 2.19 Discretized slip surface of Leshchinsky and Huang (Leshchinsky and Huang, 1992b) 2.20 63 Forces acting on a typical column of Cheng and Yip’s method (Cheng and Yip, 2007) 2.27 61 Typical column of Chen et al.’s method a) before, and b) after applying the assumptions (Chen et al., 2003) 2.26 59 Component of base shear strength at the base of column and their projection on x-y plane (Huang et al., 2002) 2.25 57 Three-dimensional model of Huang and Tsai’s method (Huang and Tsai, 2000) 2.24 55 Typical slip surface and a column in Jiang and Yamagami’s method (Jiang and Yamagami, 2004) 2.23 53 Discretization of slip surface in Lam and Fredlund’s method (Lam and Fredlund, 1993) 2.22 52 Slip surface of Cavounidis and Kalogeropoulos’ method (Cavounidis and Kalogeropoulos, 1992) 2.21 51 65 Triangular mesh and projection of slip surface in Sun et al.’s method (Sun et al., 2009) 68 2.28 Classification of optimization techniques 73 3.1 Flowchart of the research procedure 82 4.1 Plan view of discretized sliding mass (Huang et al., 2002) 94 4.2 Internal and external forces on a typical soil column, modified after Huang et al. (2002) 4.3 Base angles and sliding angle of a typical soil column (Huang and Tsai, 2000) 4.4 95 Boundaries normal forces in x- and y-directions (Huang et al., 2002) 4.5 94 102 Forces on central section of column (i,j) in x-direction, modified after Huang et al. (2002) 107 xvii 4.6 Forces on central section of column (i,j) in y-direction, modified after Huang et al. (2002) 109 4.7 Process to find the overall FOS 113 5.1 Standard flow chart of PSO (Kennedy and Eberhart, 1995) 119 5.2 Schematic structure of a particle in PSO 122 5.3 Sample of (a) local and (b) global topologies in 2D space 124 5.4 Projection of rotated ellipsoids on x-y plane 127 5.5 Schematic structures of a particle in the present study 127 5.6 Projection of disqualified slip surfaces on y-z plane 130 5.7 Three-dimensional slope model of sensitivity analysis 131 5.8 Convergence processes of swarms with different sizes 133 5.9 Total consumed time by CPU for different swarm sizes 134 5.10 Results of sensitivity tests of (a) unequal coefficients, and (b) equal coefficients 136 5.11 Results of sensitivity analysis on inertia weight 138 5.12 Results of the tests for dynamic inertia weight 138 5.13 Process to find the critical slip surface by particle swarm optimization 140 6.1 Graphical user interface of basic inputs 145 6.2 Graphical user interface of section plotter 146 6.3 Three-dimensional surface of a sample slope 146 6.4 Graphical user interface of layers properties 147 6.5 Three-dimensional model of a sample slope with layers and piezometric surface 148 6.6 Slip surfaces of a sample swarm 149 6.7 Intersection area of a sample problem 150 6.8 Discretized sliding body of a sample problem 150 6.9 Slip surfaces of qualified particles 151 6.10 Matrix calculation compare with conventional loops 152 6.11 Cropping method to reduce the time of calculations 153 6.12 Assumed model for calculation test 154 6.13 Projection of columns on x-y plane 155 6.14 Number of columns versus different grid widths 156 6.15 Percentage of area error in different tests 157 xviii 6.16 Percentage of volume error in different tests 158 6.17 Percentage of weight error in different tests 159 6.18 Total weight and total effective weight in different tests 159 6.19 Calculation time of different tests 160 6.20 Errors of total area and volume versus grid width ratio 160 7.1 Vertical cut of problem 1 (Huang and Tsai, 2000) 164 7.2 Generated model of problem 1 166 7.3 Central section of problem 2 (Xing, 1988a) 167 7.4 Generated model for case 6 of problem 2 170 7.5 Three-dimensioal FOS versus volume of the sliding mass for problem 2 172 7.6 geometry of 2D slope in problem 3 (Alkasawneh et al., 2008) 176 7.7 Two-dimensional and 3D views of model of problem 3 by (a) and (c) Plaxis 3D and (b) and (d) current study, respectively 7.8 177 Randomly generated cylindrical slip surfaces in first swarm of PSO for problem 3 in (a) cross sectional, and (b) 3D view 178 7.9 Average and maximum fitness versus iterations for problem 3 179 7.10 Minimum FOS versus iterations for problem 3 180 7.11 Exaggerated displacement vectors of Plaxis 3D result for problem 3 7.12 (a) cylindrical shape, (b) sliding mass, and (c) sliding mode of the 3D critical slip surface for problem 3 7.13 182 Generated model of problem 3 by current study in (a) plan view, (b) central cross section, and (c) 3D view 7.15 181 (a) half-plan view and (b) central cross section of geometry of problem 4 (Yamagami and Jiang, 1997) 7.14 180 184 (a) cross sectional and (b) 3D view of randomly generated ellipsoid slip surfaces in the first swarm of PSO for problem 4 185 7.16 Average and maximum fitness versus iterations for problem 3 185 7.17 Minimum FOS versus iterations for problem 3 186 7.18 (a) ellipsoid shape, (b) sliding mass, and (c) sliding mode of the 3D critical slip surface for problem 4 187 7.19 Location of Karaj city in Iran (sited as point A) 188 7.20 Karaj urban & suburban railway map (HCE-HPCE, 2010) 189 xix 7.21 Top views of (a) T1, and (b) T2 access trenches to the main tunnel in part 2, phase I of line 2 of KUR 7.22 Geological map of part 2, phase I of line 2 of KUR (DKPCE, 2005) 7.23 190 191 Geometry of trenches in (a) end section, (b) top view, and (c) central cross section (HCE, 2005) 193 7.24 A sample ignored slip surface in conventional 3D methods 194 7.25 Cross sectional and 3D view of generated models of T1 and T2 195 7.26 Randomly generated slip surfaces for the first swarm 196 7.27 Process of PSO to achieve the maximum fitness for T1 and T2 197 7.28 Trend of minimizing FOS by PSO for T1 and T2 197 7.29 Critical slip surfaces of (a) T1 and (b) T2 obtained by the present code 198 7.30 Location of the site of case study 2 (sited by red rectangular) 199 7.31 Front view of failed slope (Liew et al., 2003) 200 7.32 Boreholes and Instrumentation for case study 2 (Liew et al., 2003) 201 7.33 Cross section plan of case study 2 (Liew et al., 2003) 202 7.34 Cross section and 3D view of generated model of case study 2 203 7.35 Process of PSO toward maximum fitness for case study 2 204 7.36 Trend of minimizing FOS by PSO for case study 2 204 7.37 Critical slip surfaces of case study 2 (a) cross section and (b) 3D 205 xx LIST OF ABBREVIATIONS 2D - Two-Dimensional 3D - Three-Dimensional DP - Dynamic Programming FOS - Factor of Safety FEM - Finite Element Method GA - Genetic Algorithm KUR - Karaj Underground Railway LEM - Limit Equilibrium Method NATM New Austrian Tunneling method PSO - Particle Swarm Optimization RNG - Random Number Generation SRM - Strength Reduction Method xxi LIST OF SYMBOLS a - direction of sliding on base of column a’ - direction of sliding on x-y plane ax - inclination of column base along x-directions ay - inclination of column base along y-directions ac - total number of active columns aL - distance of left side water force from center of rotation aR - distance of right side water force from center of rotation Ae - percentage of error of area calculation Ahalf - area of half-sphere Ai,j - base area of column At - calculated area of half-sphere by the code AL - resultant water force at the left side AR - resultant water force at the right side b - horizontal width of slice bc - width of tension crack bgn(i) - best position in the swarm so far bi,j - width of the column on x-y plane bnm(i) - best position of mth neighbour of nth particle so far bpn(i) - best position of nth particle so far B - height of the side of column in y-direction c' - average effective cohesion of the soil - cohesion of the soil in terms of effective stress d - distance of the external lineear load from the center of rotation D - height of the side of column in x-direction Ds - dimension of the particles of swarm e - distance of the center of slice from the center of rotation ei,j - effective weight of column E - deformation module xxii Es - normal interslice force Ex - normal intercolumn force in x-direction Ey - normal intercolumn force in y-direction EL - normal interslice forces at left side of slice ER - normal interslice forces at right side of slice Fw - horizontal force induced by water in tension crack f - perpendicular distance of normal force and center of rotation f(x) - interslice force function of Morgenstern and Price’s method f1, f2, f3 - unit vectors for base shear force f(X) - objective function of optimization techniques Feh - horizontal force induced by earthquake Fehx - horizontal force induced by earthquake in x-direction Fehy - horizontal force induced by earthquake in y-direction Fev - vertical force induced by earthquake Fm - overall moment equation Fs - factor of safety of column Fsx - directional factors of safety in x-directions Fsy - directional factors of safety in y-directions Ft - overall force equation Fit - fitness value of particles FOS - factor of safety g1, g2, g3 - unit vectors for base normal force Gx - normal intercolumn forces along x-directions Gy - vertical shear intercolumn forces along x-directions G - resultant of intercolumn forces along x-directions h1 - height of right side of the column h2 - height of left side of the column hc - depth of tension crack hi,j - central height of column h - thickness soil layers hp - depth of point from water level hx - moment arm of normal intercolumn force in x-direction hy - moment arm of normal intercolumn force in y-direction hE - height of acting point of normal interslice force Hu - coefficient of inclination of piezometric line xxiii Hx - horizontal intercolumn shear force in x-direction Hy - horizontal intercolumn shear force in y-direction k - coefficient of seismic dynamic force K - number of the neighbours in swarm Kh - pseudo-static horizontal seismic coefficient Kv - pseudo-static vertical seismic coefficient l - external linear load on slope L - horizontal length of sliding surface Lz - external vertical load Lx - external horizontal load in x-direction Ly - external horizontal load in y-direction N - total normal force at base of column N` - effective normal force base at base of column Ns - swarm size of particle swarm optimization Nx,Ny,Nz - components of base total normal force in x- y- and z-directions p - horizontal shear intercolumn forces P - total normal force at base of slice Pv - vertical external force Px - moment of external forces in x-direction Py - moment of external forces in y-direction q - normal intercolumn forces along z-directions Q - resultant of intercolumn forces r - radius of sphere ru - pore water ratio R - radius of moment arm of shear force Rc - cohesion part of intercolumn shear force Rx,Ry,Rz - semi-radiuses of ellipsoid in x- y- and z-directions R - cohesionless parts of intercolumn shear force S - mobilized shear strength at base of column S’ - projection of mobilized shear strength on x-y plane Sf - available shear strenght of soil Sm - mobilized shear strenght at the base of slice Sx,Sy,Sz - components of base shear strength along x- y- and z- directions Sxz, Syzi - components of base shear strength in x-z and y-z planes T - base shear strength of column xxiv Ta/F - resultant of resisting forces Tx,y - resultant of base shear strength in x-y plane Tz - shear strength along z-direction - pore air pressure - pore water pressure u(0, ) - vectors of random numbers for velocity equation of swarm U - pore water force at the base of column v - velocity of particle Ve - percentage of error of volume calculation Vhalf - volume of half-sphere V - vertical intercolumn shear force Vt - calculated volume of half-sphere by the code w - inclination of the external linear load W - weight of column xh - horizontal distance of center of slice and center of rotation xv - design variables in optimization techniques xvmin - lower bound of design variables in optimization techniques xvmax - upper bound of design variables in optimization techniques x - position of particle in article swarm optimization Xs - vertical interslice shear force Xc,Yc, Zc - coordinates of center of ellipsoid in x- y- and z-directions Xv - vector of design variables in optimization techniques Xx - vertical intercolumn shear force in x-direction Xy - vertical intercolumn shear forces in y-direction X - vertical intercolumn shear forces XR - interslice shear forces at right side of slice XL - interslice shear forces at left side of the slice s - inclination of base of slice 1 - inclinations of the left side of column base 2 - inclinations of the right side of column base α - projection of direction of sliding at base of column α’i - direction of sliding on x-y plane αxz - inclination of column base along x-direction αyz - inclination of column base along y-direction β - angle of resultant intercolumn force along x-direction xxv - poisson’s ratio w - unit weight of water t - total unit weight of overburden - unit weight of soil layer s - saturated unit weight of soil layer - angle of resultant interslice forces in Spencer’s method y - width of the column in x-direction y - width of the column in x-direction Ex - resultant normal intercolumn forces in x-direction Ey - resultant normal intercolumn forces in y-direction Hx - resultant horizontal intercolumn shear forces in x-direction Hy - resultant horizontal intercolumn shear forces in y-direction Xy - resultant vertical intercolumn shear forces in y-direction Xx - resultant vertical intercolumn shear forces in x-direction - required accuracy of result - constant in velocity equation of particle swarm optimization - angle of internal friction of soil in terms of effective stress - angle between sides of column on base plane xy - rotation angle of ellipsoid in x-y plane x - total external forces in x-direction y - total external forces in y-direction - coefficient of interslice force function - constant multiplier in velocity equation of swarm ρ - direction of shear strength at base of column - total normal stress - effective normal stress - coefficient related to degree of saturation 𝜓x - inclination between action points of normal intercolumn forces 𝜓y - inclination between action points of normal intercolumn forces - inertia weight of particles in velocity equation [] - calculator of integer part xxvi LIST OF APPENDICES APPENDIX TITLE PAGE A Equations of Three-Dimensional Methods of Slope Stability 227 B Derivation of Direction of Sliding and Force Components 231 C Derivation of Directional Factors of Safety 235 D Detail Results of Verification Problem 1 237 E Detail Results of Verification Problem 2 239 F Details of Validation Case 1 244 G Coding of the Study 251 H List of Publications 315