EVALUATION OF INFINITE SLOPE STABILITY WITH VARIOUS SOILS UNDER WET-DRY CYCLE

Abstract

Rainwater infiltration is one of the main triggering factors in slope failure. Therefore, exploring the unsaturated slope behavior is essential. However, studies generally ignored the impact of soil-water characteristic curve (SWCC) hysteresis caused by wet-dry cycles in engineering practice. SWCC measured in the drying process is commonly used to estimate slope behavior in the wet-dry cycle. Three soils of Toyoura sand, Hiroshima decomposed granite soil (Masado soil), and DL clay will be taken as examples to examine the infinite slope stability under the effect of SWCC hysteresis. Firstly, this research examines soils' SWCC and suction stress characteristic curves (SSCC). Then, the factor of safety (FOS) changes are further analyzed when suction stress is considered the confining pressure. The results indicate that FOS for soils with small cohesion and air-entry value is greatly affected by SWCC hysteresis. As the depth between the selected slip surface and slope surface increases, the disparity between FOSs calculated through wetting FOS and drying FOS will decrease sharply. Therefore, for shallow slope stability analysis, only using the SWCC measured during the drying process to evaluate the entire wet-dry cycle might lead to underestimating slope failure potentiality.