Analysis of Rainfall-induced Landslide Using the Extended DDA by Incorporating Matric Suction

Abstract Rainfall-induced landslide is a common natural hazard, and one of the disaster-causing factors is the loss of apparent cohesion that is mainly caused by the dissipation of matric suction. To analyze the rainfall-induced landslide, especially the post-failure behaviors, a matric suction model is proposed and incorporated into the Discontinuous Deformation Analysis (DDA). In this model, the matric suction is simplified as an equivalent line load and updated at each time step. The safety factor of the simple sliding model simulated by the extended DDA (DDA_c) showed a good agreement with the limit equilibrium method. The simulated relationship between runout distance and the degree of saturation of the multi-block sliding model was validated by the experimental results. Finally, a rainfall-induced landslide in Fukuchi-machi was simulated using the extended DDA. The results illustrated that the apparent cohesion loss is an important mechanism for landslide initiation and a crucial reason for the long-runout distance. The presented DDA_c can be served as a qualified tool to analyze shallow slope stability and post-failure behavior involving apparent cohesion.