See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/279958969
Soil permeability related to liquefaction potential under anisotropic cyclic
triaxial test
Conference Paper · March 2011
CITATIONS
READS
2
1,169
2 authors:
Koray Ulamis
Horng-Jyh Yang
Ankara University
West Virginia University
29 PUBLICATIONS 89 CITATIONS
8 PUBLICATIONS 9 CITATIONS
SEE PROFILE
Some of the authors of this publication are also working on these related projects:
Investigation of Initial Liquefaction under Anisotropic Loading Conditions View project
Landslide hazard in residential areas, Memlik District, Ankara View project
All content following this page was uploaded by Koray Ulamis on 10 July 2015.
The user has requested enhancement of the downloaded file.
SEE PROFILE
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Soil permeability related to liquefaction potential under
anisotropic cyclic triaxial test
KORAY ULAMIS, Research Assistant , Ph.D., Department of Geological Engineering,
University of Ankara, Ankara, Turkey (visiting scholar@UNR), (ulamis@eng.ankara.edu.tr)
HORNG-JYH YANG, Lecturer, Ph.D., P.E., Department of Civil and Environmental
Engineering, University of Nevada, Reno, NV (yang@unr.edu)
ABSTRACT
The most common concerns due to the seismic load in saturated sandy soil are the excess
pore water pressure and the settlement. Without respect to the initial, partial or complete
liquefaction, the soil permeability is one of the major factors affecting the pore water pressure
generation and dissipation during and after the earthquake. Several research attempts have
investigated the effect of permeability on the liquefaction potential, using the centrifuge tests and
laminar soil box. These studies have been conducted based on specific assumptions or models.
This research focuses on the potential liquefaction hazard for saturated sandy soil under a
shallow foundation. A serious of anisotropic cyclic triaxial tests associated with digital constant
pressure permeability test is applied here for three different graded sandy materials in order to
determine the excess pore water pressure under cyclic loading. The anisotropic cyclic loading is
conducted in three different cyclic stress ratios under three different confining pressures (to
reproduce depths of 10ft, 20ft and 30ft) and two relative densities (Dr = 50% and 90%).
Additionally, a constant pressure permeability device is attached to the system; the permeability
of the soil specimen had been measured before the cyclic test. The variation of the excess pore
water pressure and the effective stress during the cyclic test is monitored for the determination of
liquefaction potential. The relation between the permeability and degradation of the effective
stress/pore pressure ratio is evaluated for the prediction of liquefaction.
481
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
INTRODUCTION
Liquefaction mechanism of the isotropically and anisotropically consolidated granular soils
has been extensively identified and researched. (Seed and Lee, 1966; Lee and Seed 1967; Seed,
and others, 1975; Seed, et al. 1983; Castro (1969, 1975); Castro and Poulos (1977); and Castro,
et al. (1982). A basic finding of Castro’s work is that anisotropic consolidation decreases
liquefaction resistance, which is exactly the opposite of the conclusion by Lee and Seed (1967).
Some recent results by Vaid and Chern (1983, 1985) show that cyclic strength can either increase
or decrease with anisotropic consolidation.
Ha, et al. (2003) concluded that, permeability during liquefaction increased 1.4 to 5 times
when compared to the original permeability. Sharp, et al. (2003) states that, permeability plays
an important role in determining the liquefaction response of a homogeneous sand deposit,
affecting especially the depth of liquefaction, the speed at which excess pore pressures dissipate
after shaking, and the character of the ground surface settlement. Dewoolkar et al. (1999)
conducted a dynamic centrifuge experiment and concluded that lower soil permeability
coefficient caused faster buildup and slower dissipation of excess pore water pressure.
This study covers cyclic triaxial testing of three different sands under anisotropic conditions,
namely the Ione sand, beach sand and washed concrete sand for medium to very dense
conditions. These are chosen due to their different particle size and shape. The samples were
fully saturated and subjected to anisotropic consolidation. All the cyclic triaxial tests were
performed using different sets of depth, cyclic stress ratio (CSR) and relative density conditions.
Based on the magnitude and corresponding number of cycles, they were subjected to deviator
cyclic loading with different cyclic stress ratios.
In addition, permeability of the samples was determined using the devices attached to the
triaxial cell. The pore water pressure ratio and k coefficient of the samples were compared to
determine the possible relation. It is concluded that, once the permeability is known, the excess
pore pressure could be predicted using the charts provided in this study. In this research, the
samples mostly generated negative pore water pressure without reaching initial liquefaction or
cyclic mobility states based on the anisotropic conditions considered.
Test Materials and Loading Conditions
The test program herein employed Ione utility sand (IS), washed concrete sand (WCS) and
beach sand (BS). Previous work has been done for the Ione sand (Norris 1977; Norris, et al. 1995,
1997; Palmer, 1997; Yang, 2005; Ulamis and Yang, 2010). The particle size distributions of
sands (Figure 1) were determined in order to identify the most common liquefiable coarse soils
(Tsuchida, 1970). Some material properties of the sands are given in Table 1.
482
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Figure 1. Particle size distribution of the sands used in this study on liquefiable soil boundaries
(adopted from Tsuchida, 1970)
Table 1. The material properties of the sands tested
Ione Sand
Washed Concrete Sand
Beach Sand
2.67
2.65
2.67
e min
0.72
0.43
0.62
e max
1.07
0.96
0.86
D50
0.195
0.90
0.70
Cu
2.90
4.33
2.0
Cc
0.96
0.64
1.28
SP
SP
SP
50 and 90
50 and 90
50 and 90
Gs
USCS
Dr
483
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
For depicting the anisotropic conditions, a case of 5x5’ footing and the vertical stresses
caused at depths of 10, 20 and 30’ by this loading was set up (Figure 2). Total and effective
vertical stresses at these depths and the confining pressures to be applied during the tests were
derived from this case. Static triaxial drained tests were run in order to derive the internal friction
angle to be used for the confining pressure calculation. The cell pressure, deviator stress for
anisotropic consolidation and cyclic deviator stresses were calculated for three different depths
and CSR values of 0.2, 0.3 and 0.4 (Table 2).
Figure 2. Anisotropic loading conditions at verious depths caused by footing
Table 2. Different anisotropic loading conditions based on CSR=0.2 and 10’ depth
Ione sand
Washed concrete sand
Beach sand
Effective, v’
28
25.7
28.95
Confining, c’
12.6
9.88
11.87
Anisotropic consolidation, d
15.4
15.82
16.39
Deviator Cyclic, ± cy’
21.29 & 15.4
17.6 & 15.8
18.85 & 16.385
◦
36
40
38
k0
0.38
0.42
0.41
484
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Cyclic Triaxial and Permeability Tests
Anisotropic cyclic triaxial tests were performed on the three different types of sand with two
relative densities. After preparing the samples with three different confining pressures
representing the depths of 10’,20’ and 30’, deviator loads were applied to consolidate the
samples for providing anisotropic loading conditions (Figure 3). Based on the maximum shear
stresses relevant to the CSR with respect to the vertical effective stress, undrained tests were run
with cyclic deviator loads. The pore water pressure and pore pressure ratio were recorded in
order to compare to the permeability afterwards. A total of 26 cycles were run corresponding to
M=8.5 earthquake offered by Seed and Idriss (1982). A pair of GDS Advanced Pressure/Volume
Controller (ADVDPC) devices have been attached to the cyclic triaxial cell in order to measure
the in and out volume of water precisely using constant pressure. The cell pressure
corresponding to the considered depths was applied to the triaxial cell and the differential
volume of water through the system was recorded to obtain the permeability of the samples.
Figure 3. (a) Schematic representation of the anisotropic loading conditions, (b) application of
maximum shear stress and cyclic deviator stresses
485
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Permeability Related to Pore Pressure Ratio
Since it is well known that the initial liquefaction is defined as the point where the effective
stress reaches zero because of the generation of high excess pore water pressure, it is obvious
that this situation could be a function of soil permeability. Previous studies have proved that the
excess pore water pressure and permeability are subject to changes during the liquefaction. Most
of these studies have been based on models or centrifuge studies. For our anisotropic condition,
all the samples generated negative pore water pressure due to dilatancy even when their particle
sizes and distributions are different. A total of 54 tests were run and in most of these the axial
strains did not reach up to even 1%. The pore pressure ratio (ru) decreases with depth due to
higher confining pressure and shear stress relevant to the CSR. As expected, the permeability
decreases with depth as well. The permeability of the washed concrete sand is higher than that
beach sand whereas Ione sand has the lowest value. When the permeability vs. ru is plotted on a
chart, a linear tendency is demonstrated. This leads to have the idea of using the permeability
coefficient to predict the excess pore water pressure at given depths. All the test data are plotted
on the charts (Figures 4 and 5)
Figure 4. Permeability vs ru for relative density (Dr) of 50 %
486
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Figure 5. Permeability vs ru for relative density (Dr) is 90 %
CONCLUSIONS
In this study, a case of anisotropic loading and applying a cyclic deviator load with respect
to the CSR and shear stress was considered. Three types of sands were tested using three
different CSR and two relative density conditions. The excess pore water pressure generation and
lateral effective stress values were recorded in order to obtain the pore water pressure ratio (ru).
In addition the permeability has been determined using the GDS devices attached to the cell.
The samples have generated positive pore water pressure with negligible strains. Only the
ione sand with the lowest confining pressure and the coarsest washed concrete sand had some
positive pore water pressure but so close to zero. Ione sand and beach sand are mostly dilatant
compared to washed concrete sand. The axial (vertical) strains generated by this coarse sand are
higher than others. Contractive response is rather common for the washed concrete sand, but
under anisotropic conditions, the pore water pressure ratio is close for all the sand types tested.
487
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Permeability increases from Ione sand to beach and washed concrete sand which is as
expected. A numerical relation between permeability and pore water pressure generation is not
easy especially for the undrained case. Here, all the sand samples have been subjected to
permeability first, cyclic triaxial test afterwards using the same cell. When the permeability and
pore water pressure ratio values are plotted, a linear relation is determined.
The samples did not reach the initial liquefaction or high axial strains indicating cyclic
mobility state but it is clearly seen that generation of the excess pore water pressure increases
with the permeability even if the soils are dilatant. The permeability reduces with depth and
increasing CSR. The coarsest washed concrete sand generally has higher ru compared to others
due to its particle size. Ione sand causes high ru when the confining pressure is lowest but beach
sand is consistent under variation of depth and CSR, producing negative pore water pressure.
The main benefit using the charts provided at two relative densities is, one can predict the
excess pore water pressure generation for the specific type of soil if permeability is known. If the
CSR values are higher and the soil is close to liquefaction, ru will be close to 1.0 and pore water
pressure can be derived from this point.
REFERENCES
Castro, G., 1969, Liquefaction of Sands: PhD thesis, Harvard Univ., Cambridge. Mass.
Castro, G., 1975, Liquefaction and cyclic mobility of saturated sands: J. Geotech. Engrg. Div.,
ASCE, 101 (GT6), pp. 551-569.
Castro, G. and Poulos, S.J., 1977, Factors affecting liquefaction and cyclic mobility: J. Geotech.
Engrg. Div., ASCE, 103 (GT6), pp. 501-516.
Castro. G.. Poulos, S., France, J. W. and Enos, J. L., 1982, Liquefaction induced by cyclic
loading: Report- 10 NSF, Geotechnical Engineering, Winchester. Mass.
Dewoolkar, M. M., Ko, H.-Y., Stadler, A. T., and Astaneh, S. M. F., 1999, A substitute pore
fluid for seismic centrifuge modeling: Geotechnical Testing Journal, 22~3, 196–210.
Ha, I., S., Park, Y.,H., and Kim, M., M., 2003, Dissipation Pattern of Excess Pore Pressure After
Liquefaction in Saturated Sand Deposits : TRB, 1821, pp 59-67.
Lee, K. L., and Seed, H. B., 1967, Cyclic stress conditions causing liquefaction of sand: J. Soil
Mech. Found. Div., ASCE, 93(SM1), 47-70.
Norris, G.M., 1977, The Drained Shear Strength of Uniform Quartz Sand as Related to Particle
Size and Natural Variation in Particle Shape and Surface Roughness: Ph.D. Thesis,
University of California, Berkeley, 523 pp.
Norris, G.M., Madhu, R., Ashour, M., and Valceschini, R., 1995, Liquefaction and Residual
Strength of Loose Sands From Drained Triaxial Tests: Report 2 to Army Corps of
Engineers (WES). CCEER-95-2, University of Nevada, Reno.
488
Proceedings, 43rd Annual Symposium on Engineering Geology and Gotechnical Engineering
Biggar, Luke and Werle (eds) University of Nevada, Las Vegas, March 23-25, 2011
Norris, G.M., Siddharthan, R., Zafir, Z., Madhu, R., 1997, Liquefaction and Residual Strength
of Sands from Drained Triaxial Tests: Journal of Geotechnical and Geoenvironmental
Engineering, ASCE, Vol. 123, No. 3, pp. 220-228.
Palmer, J., 1997. Undrained Lateral Compression Response from Drained Lateral Compression
Test: Ph.D. Thesis, University of Nevada, Reno, 440 pp.
Seed, H. B., and Idriss, I. M., 1982, Ground motions and soil liquefaction during earthquakes:
Earthquake Engineering Research Institute Monograph, Oakland, CA.
Seed, H. B., Idriss, I. M., and Arango, I.,1983, Evaluation of liquefaction potential using field
performance data : J. Geotech. Engrg. Div., ASCE, 109(3),458-482.
Seed, H. Bolton, Mori, Kenji, and Chan, Clarence K., 1975, Influence of Seismic History on the
Liquefaction Characteristics of Sands: Report No. EERC 75- 25, EERC, University of
California, Berkeley, CA.
Seed, H. B and Lee, K.L., 1966, Liquefaction of saturated sands during cyclic loading: J. Soil
Mech. Found. Div., ASCE, 92(SM6), pp. 105-134.
Sharp, M.K., Dobry, R. and Abdoun, T.,2003, Liquefaction Centrifuge Modeling of Sands of
Different Permeability: Journal of Geotechnical and Geoenvironmental Engineering,
Vol. 129, No. 12,1083-1091.
Tsuchida, H., 1970, Prediction and countermeasure against the liquefaction in sand deposits:
Seminar in the Port and Harbor Research Institute, abstracts, pp. 3.1-3.33, Japan (In
Japanese)
Ulamis, K., and Yang, J.H., 2010. The prediction of the excess pore water pressure generation
and the vertical strain in different cyclic stress ratio loadings under anisotropic undrained
conditions: 2010 GSA Annual Meeting - Denver Colorado, In DVD.
Vaid, Y. P., and Chem, J. C., 1985, Cyclic and monotonic undrained response of saturated
sands :Advances in the Art of Testing Soils Under Cyclic Conditions, Session No. 52,
Annual Convention and Exposition, ASCE, Detroit, Mich., 120-147.
Vaid,Y .P., and Chern, J, .C., 1983, Mechanism of deformation during cyclic undrained loading
of saturated sand: Soil Dynamics and Earthquake Engineering, 2, No. 3, pp. 171-177.
Yang, H, J., 2005, Extension / Compression Test Stress-Strain-Volume Change
Characterization under Drained Conditions: Ph.D. Thesis, University of Nevada, Reno, 431
pp.
489
View publication stats