Numerical Study of the Effect of Rainfall on the Stability of an Unsaturated Clay Slope
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2025-02-27
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American Society of Civil Engineers (ASCE)
Abstract
Changing precipitation patterns due to climate change have increased the frequency and intensity of extreme weather events, causing widespread slope instability issues triggered by heavy rainfall. For instance, a storm in California in February 2024 triggered 475 mudslides in Los Angeles damaging nearly two dozen houses. This highlights the need to study the effects of rainfall characteristics and soil conditions on the stability of unsaturated slopes. This study examined the combined impact of rainfall characteristics and initial soil conditions on unsaturated clay slopes. Using a statistical analysis for the optimal experimental design, a full factorial approach required 360 numerical models, later optimized to eleven finite element models developed in SEEP/W, SIGMA/W, and SLOPE/W of GeoStudio. The factor of safety of the slope was found to depend on the void ratio and rainfall characteristics. Seepage velocity and deformation occurring in the slope was found to be a function of intensity of rainfall and the initial void ratio of the soil. Rainwater infiltration indicated a decrease in suction strength of the unsaturated slope leading to decrease in the shear strength of the soil resulting in lower factor of safety and potential instability issues.
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This is a manuscript of a proceeding published as Roy, Rupsa, Beena Ajmera, and Binod Tiwari. "Numerical Study of the Effect of Rainfall on the Stability of an Unsaturated Clay Slope." In Geotechnical Frontiers 2025, pp. 46-55. doi: https://doi.org/10.1061/9780784485965.005.
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