Proceedings of the
8th International Symposium on Geotechnical Safety and Risk (ISGSR)
14 – 16 December 2022, Newcastle, Australia
Editors: Jinsong Huang, D.V. Griffiths, Shui-Hua Jiang, Anna Giacomini, Richard Kelly
doi:10.3850/978-981-18-5182-7_22-002-cd
Stability Analysis and Failure Mechanism of Three-Dimensional Heterogeneous Slope Under Steady State Rainfall
School of Engineering and Technology, China University of Geosciences, Beijing, Beijing, China.
ABSTRACT
Matrix suction contributes to the stability of unsaturated soil slopes. It is generally accepted that rainfall infiltration will reduce the matrix suction of the soil and lead to the instability and failure of the unsaturated soil slope. The van Genuchten model can be used to characterize the relationship of matrix suction with saturation. Previous studies mainly focused on two-dimensional unsaturated soil slopes, which can not consider the impact of the variability of parameters in three-dimensional space on slope stability. The 2D simplification makes the research relatively simple and deviates from the real situation. In the actual slope, the parameters such as saturated hydraulic conductivity, and of van Genuchten model have 3D spatial variability, and affects rainfall infiltration. The heterogeneity of these parameters leads to the heterogeneity distribution of matrix suction in space, so the spatial distribution of soil strength is also heterogeneous. Previous sensitivity analysis studies show that in the three parameters of saturated hydraulic conductivity, and of van Genuchten model, has a greater influence on the distribution of matrix suction than the other two. The research in this paper is focused on an ideal 3D unsaturated slope under steady state rainfall, and compared with 2D model. Monte-Carlo method and random fields are used to randomly simulate the spatial distribution field of , steady state flow is calculated in COMSOL, and the suction stress is brought into the finite element program to calculate the slope stability. The results show that the spatial variability of the affects the deformation and failure surface location of the 3D unsaturated soil slope. The analysis of 3D slope deformation mechanism shows that the deformation and failure of unsaturated soil slope occur in the region with weak suction.
Keywords: Three-dimensional slope, Unsaturated slope, Hydraulic parameters, deformation mechanism.
