3D Analysis of Stability for Rainfall Induced Landslides in Unsaturated Soils

In the stability analysis of landslides, it is required to consider the rainfall intensity, geographical features and hydromechanical behavior in unsaturated layers. The actual landslide can be simulated rigorously by 3D analysis. The unsaturated shear strength can be evaluated from soil water retention curves based on the suction stress which has generalized Bishop’s effective stress. The unsaturated soils become unstable as the saturation ratio increases and subsequently the effective stress decreases. The assessment of landslide stability is based on the effective stress theory in unsaturated soils.

By the GIS based analysis system, the slope stability is estimated for wide mountain area in Korea. From digital map data, the contour map and elevation are extracted and the mesh is created as a preprocess. In each cell, the infiltration and stability analysis are performed step by step. In the area of actual landslides, the infiltration analysis on transient flow has been performed one dimensionally for the actual rainfall record. The stability analysis is subsequently performed three dimensionally based on the unsaturated effective stress principle. It is verified that the 3D stability analysis can simulate the actual landslide rigorously.

 

 Acknowledgements This research is supported by grant from Korean NRF (2019R1A2C1003604), which are greatly appreciated.