Investigation of Large Deformation Failure Characteristics of Slopes Under Rainfalls Considering Spatial Variability of Hydraulic Conductivity

Assessing the failure characteristics of slopes under rainfall is an essential prerequisite for preventing and early warning of landslide hazards.To reveal the impact of the spatial variability of hydraulic conductivity on the large deformation characteristics of slopes under rainfalls,the study proposes a coupling method of the random limit equilibrium and material point method (RLE-MPM) by making use of the high computational efficiency of limit equilibrium method and the capability of the material point method to simulate large deformation.An interface program for the implementation of MATLAB-HYDRUS-Anura 3D software is developed.First,the rainfall infiltration process of the slope is modeled using HYDRUS to obtain the distribution of water content and pore water pressure for each soil layer.Then,the local shear strength method (LSS) is used to update the equivalent shear strength and gravity for each material point.Finally,the random material point method (RMPM) is adopted to calculate the probability of slope failure,identify slope failure modes,and evaluate the large deformation failure characteristics of slopes under rainfalls.The proposed RLE-MPM can simulate the hydraulic-large deformation coupling process in the rainfall-induced landslides in Tokai-Hokuriku, Japan and the obtained final landslide accumulation pattern is generally consistent with the field investigations.Compared to RMPM,the proposed RLE-MPM has higher efficiency in calculating the probability of slope failure,and can effectively identify three kinds of failure modes of the slope under rainfalls,namely the complete failure mode,shear failure mode,and progressive failure mode.Additionally,the rainfall duration can greatly affect the large deformation failure modes and characteristics of the heterogeneous slope.