Abstract
This study presents stability analyses of layered soil slopes in unsaturated conditions and uses a limit equilibrium method to determine the factor of safety involving suction stress of unsaturated soil. One-dimensional steady infiltration and evaporation conditions are considered in the stability analyses. An example of a two-layered slope in clay and silt is selected to verify the used method by comparing with the results of other methods. Parametric analyses are conducted to explore the influences of the matric suction on the stability of layered soil slopes. The obtained results show that larger suction stress provided in unsaturated clay dominates the stability of the layered slopes. Therefore, the location and thickness of the clay layer have significant influences on slope stability. As the water level decreases, the factor of safety reduces and then increases gradually in most cases. Infiltration/evaporation can obviously affect the stability of unsaturated layered slopes, but their influences depend on the soil property and thickness of the lower soil layer.
Similar content being viewed by others
References
Clague J J, Stead D. Landslides: Types, Mechanisms and Modeling. New York: Cambridge University Press, 2012
Fuchu D, Lee C F, Sijing W. Analysis of rainstorm-induced slide-debris flows on natural terrain of Lantau Island, Hong Kong (China). Engineering Geology, 1999, 51(4): 279–290
Lu N, Wayllace A, Oh S. Infiltration-induced seasonally reactivated instability of a highway embankment near the Eisenhower Tunnel, Colorado, USA. Engineering Geology, 2013, 162: 22–32
Sorbino G, Nicotera M V. Unsaturated soil mechanics in rainfall-induced flow landslides. Engineering Geology, 2013, 165: 105–132
Fredlund D G, Rahardjo H. Soil Mechanics for Unsaturated Soils. Hoboken: John Wiley & Sons, Inc, 1993
Lu N, Likos W J. Suction stress characteristic curve for unsaturated soil. Journal of Geotechnical and Geoenvironmental Engineering, 2006, 132(2): 131–142
Vahedifard F, Leshchinsky D, Mortezaei K, Lu N. Effective stress-based limit-equilibrium analysis for homogeneous unsaturated slopes. International Journal of Geomechanics, 2016, 16(6): D4016003
Sun D A, Wang L, Li L. Stability of unsaturated soil slopes with cracks under steady-infiltration conditions. International Journal of Geomechanics, 2019, 19(6): 04019044
Wang L, Hu W, Sun D A, Li L. 3D stability of unsaturated soil slopes with tension cracks under steady infiltrations. International Journal for Numerical and Analytical Methods in Geomechanics, 2019, 43(6): 1184–1206
Yang M, Deng B. Stability study of slope reinforced with piles under steady unsaturated flow conditions. Computers and Geotechnics, 2019, 109: 89–98
Masoudian M S, Hashemi Afrapoli M A, Tasalloti A, Marshall A M. A general framework for coupled hydro-mechanical modelling of rainfall-induced instability in unsaturated slopes with multivariate random fields. Computers and Geotechnics, 2019, 115: 103162
Gholampour A, Johari A. Reliability-based analysis of braced excavation in unsaturated soils considering conditional spatial variability. Computers and Geotechnics, 2019, 115: 103163
Stockton E, Leshchinsky B, Xie Y, Olsen M J, Leshchinsky D. Limit equilibrium stability analysis of layered slopes: A generalized approach. Transportation Infrastructure Geotechnology, 2018, 5(4): 366–378
Kumar J, Samui P. Stability determination for layered soil slopes using the upper bound limit analysis. Geotechnical and Geological Engineering, 2006, 24(6): 1803–1819
Guo S, Li N, Liu W, Ma Z, Liu N, Lv G. Influence of both soil properties and geometric parameters on failure mechanisms and stability of two-layer undrained slopes. Advances in Materials Science and Engineering, 2020, 2020: 4253026
Lim K, Li A J, Lyamin A V. Three-dimensional slope stability assessment of two-layered undrained clay. Computers and Geotechnics, 2015, 70(OCT): 1–17
Wu G, Zhang R, Zhao M, Zhou S. Undrained stability analysis of eccentrically loaded strip footing lying on layered slope by finite element limit analysis. Computers and Geotechnics, 2020, 123: 103600
Bishop A W. The experimental study of partly saturated soil in the triaxial apparatus. In: 5th International Conference on Soil Mechanics & Foundation Engineering. Paris, 1961, 1: 13–21
Lu N, Likos W J. Unsaturated Soil Mechanics. Hoboken: John Wiley & Sons, Inc, 2004
Lu N, Godt J W, Wu D T. A closed-form equation for effective stress in unsaturated soil. Water Resources Research, 2010, 46(5): W05515
Vangenuchten M T. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 1980, 44(5): 892–898
Mualem Y. A new model for predicting the hydraulic conductivity of unsaturated porous media. Water Resources Research, 1976, 12(3): 513–522
Lu N, Kaya M, Collins B D, Godt J W. Hysteresis of unsaturated hydromechanical properties of a silty soil. Journal of Geotechnical and Geoenvironmental Engineering, 2013, 139(3): 507–510
Baker R, Garber M. Theoretical analysis of the stability of slopes. Geotechnique, 1978, 28(4): 395–411
Leshchinsky D. Short-term stability of reinforced embankment over clayey foundation. Soil and Foundation, 1987, 27(3): 43–57
Leshchinsky D. Slope stability analysis: Generalized approach. Journal of Geotechnical Engineering, 1990, 116(5): 851–867
Spencer E. A method of analysis of the stability of embankments assuming parallel inter-slice forces. Geotechnique, 1967, 17(1): 11–26
Acknowledgements
This study was supported by the National Natural Science Foundation of China (Grant Nos. 52078185 and 51878248).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dai, G., Zhang, F. & Wang, Y. Stability analysis of layered slopes in unsaturated soils. Front. Struct. Civ. Eng. 16, 378–387 (2022). https://doi.org/10.1007/s11709-022-0808-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11709-022-0808-2