Influence of Stress State on Soil-Water Characteristics and Slope Stability
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 126, Issue 2
Abstract
A soil-water characteristic curve defines the relationship between the soil (matric) suction and either the water content or the degree of saturation. Physically, this soil-water characteristic is a measure of the water storage capacity of the soil for a given soil suction. Conventionally, the soil-water characteristic curves (SWCCs) are determined in the laboratory using a pressure plate apparatus in which vertical or confining stress cannot be applied. For investigating the influence on the stress state on the soil-water characteristics, a new stress controllable pressure plate apparatus has been developed. Effects of K0 stress conditions on the SWCCs of an “undisturbed” volcanic soil in Hong Kong are determined and illustrated. The net normal stresses considered in the apparatus are 40 and 80 kPa, which are appropriate for many slope failures in Hong Kong. Experimental results show that the soil-water characteristic of the soil specimens is strongly dependent on the confining stress. Numerical analyses of transient seepage in unsaturated soil slopes using the measured stress-dependent soil-water characteristic curves predict that the distributions of pore-water pressure can be significantly different from those predicted by the analyses using the conventional drying SWCC. For the cut slope and the rainfall considered, the former analyses predicted a considerably lower factor of safety than that by the latter analyses. These results suggest that wetting stress-dependent soil-water characteristic curves should be considered for better and safer assessment of slope instability.
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References
1.
Anderson, M. G., and Pope, R. G. (1984). “The incorporation of soil water physics models into geotechnical studies of landslide behavior.” Proc., 4th Int. Symp. on Landslides, Vol. 4, 349–353.
2.
Brand, E. W. (1984). “Landslides in south Asia: A state-of-art report.” Proc., 4th Int. Symp. on Landslides, Vol. 1, 17–59.
3.
Fredlund, D. G., Morgenstern, N. R., and Widger, R. A. (1978). “The shear strength of unsaturated soil.” Can. Geotech. J., Ottawa, 15, 313–321.
4.
Fredlund, D. G., and Rahardjo, H. (1993). Soil mechanics for unsaturated soils. Wiley, New York.
5.
Fredlund, D. G., and Xing, A. (1994). “Equations for the soil-water characteristic curve.” Can. Geotech. J., Ottawa, 31, 521–532.
6.
Fredlund, D. G., Xing, A., and Huang, S. (1994). “Predicting the permeability functions for unsaturated soils using the soil-water characteristic curve.” Can. Geotech. J., Ottawa, 31, 533–546.
7.
Fukuoka, M. (1980). “Landslides associated with rainfall.” Geotech. Engrg. J., 11, 1–29.
8.
Guide to rock and soil descriptions (GEOGUIDE). (1998). Geotechnical Control Office, Public Works Department of Hong Kong, Hong Kong.
9.
Hilf, J. W. ( 1956). “An investigation of pore-water pressure in compacted cohesive soils,” PhD dissertation, Tech. Memo. No. 654, U.S. Dept. of the Interior, Bureau of Reclamation, Design and Construction Division, Denver.
10.
Lam, C. C., and Leung, Y. K. ( 1995). “Extreme rainfall statistics and design rainstorm profiles at selected locations in Hong Kong.” Tech. Note No. 86. Royal Observatory, Hong Kong.
11.
Lam, L., Fredlund, D. G., and Barbour, S. L. (1987). “Transient seepage model for saturated-unsaturated soil systems: A geotechnical engineering approach.” Can. Geotechn. J., Ottawa, 24, 565–580.
12.
Lim, T. T., Rahardjo, H., Chang, M. F., and Fredlund, D. G. (1996). “Effect of rainfall on matric suctions in residual soil slope.” Can. Geotech. J., Ottawa, 33, 618–628.
13.
Lumb, P. B. (1975). “Slope failures in Hong Kong.” Quarterly J. of Engrg. Geol., 8, 31–65.
14.
Malone, A. W., and Pun, W. K. (1997). “New engineering tools for landslip risk control.” Proc., 2nd Int. Symp. on Struct. and Found. in Civ. Engrg., Hong Kong, C. K. Shen, J. S. Kuang, and C. W. W. Ng, eds., 1–27.
15.
Ng, C. W. W., and Pang, Y. W. (1998). “Lai Ping road landslide investigation—Specialist testing of unsaturated soils.” Tech. Rep., Geotechnical Engineering Office of the Hong Kong Special Administrative Region, Hong Kong.
16.
Ng, C. W. W., and Shi, Q. (1998). “A numerical investigation of the stability of unsaturated soil slopes subjected to transient seepage.” Comp. and Geotechnics, 22, 1–28.
17.
Rahardjo, H., Leong, E. C., Gasmo, J. M., and Deutscher, M. S. (1998). “Rainfall-induced slope failures in Singapore: Investigation and repairs.” Proc., 13th Southeast Asian Conf., Vol. 1, 147–152.
18.
SEEP/W (Version 4) for finite element seepage analysis and SLOPE/W for slope stability analysis. (1998). Geo-slope International, Canada.
19.
SoilVision (version 1.2). (1997). Soilvision Systems Ltd., Sask., Saskachewan, Canada.
20.
Tung, Y. K., Ng, C. W. W., and Liu, J. K. (1999). “Lai Ping road landslide investigation—Three dimensional groundwater flow computation.” Tech. Rep.—Part I, Geotechnical Engineering Office of the Hong Kong Special Administrative Region, Hong Kong.
21.
Vanapalli, S. K., Fredlund, D. G., Pufahl, D. E., and Clifton, A. W. (1996). “Model for the prediction of shear strength with respect to soil suction.” Can. Geotech. J., Ottawa, 33, 379–392.
22.
Vanapalli, S. K., Pufahl, D. E., and Fredlund, D. G. (1998). The effect of stress state on the soil-water characteristic behavior of a compacted sandy-clay till.” Proc., 51st Can. Geotech. Conf., 81–86.
23.
Vanapalli, S. K., Pufahl, D. E., and Fredlund, D. G. (1999). “The effect of soil structure and stress history on the soil-water characteristics of a compacted till.” Géotechnique, London, 49(2), 143–159.
24.
Wilson, G. W. ( 1997). “Surface boundary flux modeling for unsaturated soils.” Unsaturated soil engineering practice, Geotech. Spec. Publ. No. 68, ASCE, New York, 38–65.
25.
Wolle, C. M., and Hachich, W. (1989). “Rain-induced landslides in south-eastern Brazil.” Proc., 12th Int. Conf. Soil Mech. and Found. Engrg., Vol. 3, 1639–1644.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 126 • Issue 2 • February 2000
Pages: 157 - 166
History
Received: Mar 10, 1999
Published online: Feb 1, 2000
Published in print: Feb 2000
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