Active Earth Pressures for Unsaturated Retaining Structures
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 141, Issue 11
Abstract
Although commonly ignored in classical earth pressure methods, precipitation-induced failures in retaining structures highlight a need for explicit consideration of negative pore pressures or matric suction. Changes in the degree of saturation in the backfill can significantly affect active earth pressures. This paper presents an analytical framework for calculating the thrust of active earth pressures under unsaturated steady flow conditions. The proposed method addresses limitations associated with the collapse mechanism and effective stress representation in alternative analytical methods. The formulation was derived by implementing an analytical solution for one-dimensional (1D) steady flow into a limit equilibrium–based effective stress analysis. A closed-form solution for the thrust was obtained by employing a log spiral surface, considering the effect of tension cracks, backslope inclination, and batter for soils with variable backfill saturation. A unified effective stress representation was used to describe the state of stress in partially saturated soils. The method was evaluated for different hypothetical soil types, and the effect of infiltration on lateral earth pressures was demonstrated. This approach presents a useful tool for explaining the true service state behavior of walls and evaluating the forensics of failed structures.
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Acknowledgments
The authors would like to thank Professor Dov Leshchinsky and Dr. Hossein Parishani for their constructive comments and suggestions regarding the formulation and programming conducted in this study.
References
Anderson, D. G., Martin, G. R., Lam, I., and Wang, J. N. (2008). “Seismic analysis and design of retaining walls, buried structures, slopes, and embankments.”, Transportation Research Board, Washington, DC.
Bishop, A. W. (1959). “The principle of effective stress.” Tek Ukeblad, 106(39), 859–863.
Damiano, E., and Mercogliano, P. (2013). “Potential effects of climate change on slope stability in unsaturated pyroclastic soils.” Landslide science and practice: Volume 4: Global environmental change, C. Margottini, P. Canuti, and K. Sassa, eds., Taylor & Francis Group, London, 15–25.
Ebrahimi, S. (2011). “Extension of Mononobe-Okabe approach to unstable slopes.” M.S. thesis, Univ. of Delaware, Newark, DE.
Fredlund, D. G., and Morgenstern, N. R. (1977). “Stress state variables for unsaturated soils.” J. Geotech. Engrg. Div., 103(5), 447–466.
Fredlund, D. G., and Rahardjo, H. (1993). Soil mechanics for unsaturated soils, Wiley, New York.
Fredlund, D. G., Sheng, D., and Zhao, J. (2011). “Estimation of soil suction from the soil-water characteristic curve.” Can. Geotech. J., 48(2), 186–198.
Gardner, W. R. (1958). “Some steady state solutions of the unsaturated moisture flow equation with application to evaporation from a water table.” Soil Sci., 85(4), 228–232.
Godt, J. W., Baum, R., and Lu, N. (2009). “Landsliding in partially saturated materials.” Geophys. Res. Lett., 36(2), L02403.
Hong, G. T. (2008). “Earth pressures and deformations in civil infrastructure in expansive soils.” Ph.D. dissertation, Texas A&M Univ., College Station, TX.
Kim, S. K., and Borden, R. H. (2013). “Numerical simulation of MSE wall behavior induced by surface-water infiltration.” J. Geotech. Geoenviron. Eng., 2110–2124.
Koerner, R. M., and Koerner, G. R. (2013). “A data base, statistics and recommendations regarding 171 failed geosynthetic reinforced mechanically stabilized earth (MSE) walls.” Geotext. Geomembr., 40, 20–27.
Leshchinsky, D., (1997). “Design procedure for geosynthetic reinforced steep slopes.”, Geotechnical Laboratory, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS.
Leshchinsky, D., Ebrahimi, S., Vahedifard, F., and Zhu, F. (2012). “Extension of Mononobe-Okabe approach to unstable slopes.” Soils Found., 52(2), 239–256.
Leshchinsky, D., and Tatsuoka, F. (2013). “Performance, design, and redundancy: Geosynthetic reinforced walls in the public sector.” Geosynthetics, 31(3), 12–21.
Leshchinsky, D., and Zhu, F. (2010). “Resultant force of lateral earth pressure in unstable slopes.” J. Geotech. Geoenviron. Eng., 1655–1663.
Liang, W., Zhao, J., Li, Y., Zhang, C., Wang, S. (2012). “Unified solution of Coulomb’s active earth pressure for unsaturated soils without crack.” Appl. Mech. Mater., 170–173, 755–761.
Likos, W., Lu, N., and Godt, J. (2014). “Hysteresis and uncertainty in soil water-retention curve parameters.” J. Geotech. Geoenviron. Eng., 04013050.
Lu, N. (2008). “Is matric suction a stress variable?” J. Geotech. Geoenviron. Eng., 899–905.
Lu, N., Godt, J. W., and Wu, D. T. (2010). “A closed-form equation for effective stress in unsaturated soil.” Water Resour. Res., 46(5), W05515.
Lu, N., Kaya, M., Collins, B. D., and Godt, J. W. (2013). “Hysteresis of unsaturated hydromechanical properties of a silty soil.” J. Geotech. Geoenviron. Eng., 507–510.
Lu, N., Kim, T-H., Sture, S., and Likos, W. J. (2009). “Tensile strength of unsaturated sand.” J. Eng. Mech., 1410–1419.
Lu, N., and Likos, W. J. (2004). Unsaturated soil mechanics, Wiley, New York.
Lu, N., and Likos, W. J. (2006). “Suction stress characteristic curve for unsaturated soil.” J. Geotech. Geoenviron. Eng., 131–142.
Mualem, Y. (1976). “A new model for predicting hydraulic conductivity of unsaturated porous media.” Water Resour. Res., 12(3), 513–522.
Pufahl, D., Fredlund, D., and Rahardjo, H. (1982). “Lateral earth pressures in expansive clay soils.” Can. Geotech. J., 20(2), 228–241.
Rahardjo, H., Rezaur, R. B., Leong, E. C., Alonso, E. E., Lloret, A., and Gens, A. (2008). “Monitoring and modeling of slope response to climatic changes.” Proc., 10th Int. Symp. on Landslides and Engineered Slopes, Z. Chen, J.-M. Zhang, K. Ho, F.-Q. Wu, and Z.-K. Li, eds., CRC, London, 67–84.
Tavakkoli, N., and Vanapelli, S. K. (2011). “Rational approach for the design of retaining structures using the mechanics of unsaturated soils.” Proc., 2011 Pan-American CGS Geotechnical Conf., Canadian Geotechnical Society, Richmond, BC, Canada.
Vahedifard, F., Leshchinsky, B. A., Sehat, S., and Leshchinsky, D. (2014). “Impact of cohesion on seismic design of geosynthetic-reinforced earth structures.” J. Geotech. Geoenviron. Eng., 04014016.
Vahedifard, F., Leshchinsky, D., and Meehan, C. L. (2012). “Relationship between the seismic coefficient and the unfactored force of geosynthetic in reinforced earth structures.” J. Geotech. Geoenviron. Eng., 1209–1221.
Valentine, R. J. (2013). “An assessment of the factors that contribute to the poor performance of geosynthetic-reinforced earth retaining walls.” Proc., Int. Symp. on Design and Practice of Geosynthetic-Reinforced Soil Structures, H. I. Ling, G. Gottardi, D. Cazzuffi, J. Han, and F. Tatsuoka, eds., DEStech, Lancaster, PA, 318–327.
Vanapalli, S. K., Fredlund, D. E., Pufahl, D. E., and Clifton, A. W. (1996). “Model for the prediction of shear strength with respect to soil suction.” Can. Geotech. J., 33(3), 379–392.
van Genuchten, M. Th. (1980). “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.” Soil Sci. Soc. Am. J., 44(5), 892–898.
Yeh, T.-C. (1989). “One-dimensional steady state infiltration in heterogeneous soils.” Water Resour. Res., 25(10), 2149–2158.
Yoo, C., and Jung, H. (2006). “Case history of geosynthetic reinforced segmental retaining wall failure.” J. Geotech. Geoenviron. Eng., 1538–1548.
Zhang, C., Zhao, J., Zhang, Q., and Xu, F. (2010). “Unified solutions for unsaturated soil shear strength and active earth pressure.” Experimental and applied modeling of unsaturated soils, Geotechnical Special Publication No. 202, L. R. Hoyos, X. Zhang, and A. J. Puppala, eds., ASCE, Reston, VA, 218–224.
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© 2015 American Society of Civil Engineers.
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Received: Jun 12, 2014
Accepted: Apr 28, 2015
Published online: Jun 9, 2015
Published in print: Nov 1, 2015
Discussion open until: Nov 9, 2015
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