Abstract
Recently, the frequency of rainfall induced landslide has drastically been increasing in Asian countries due to climate change. Also in Japan, shallow landslide caused by torrential rainfall, which was rarely observed in the past, has frequently occurred. Therefore, it is important to clarify the mechanism of rainfall induced slope failure in order to mitigate landslide risks. From such a viewpoint, authors have conducted field monitoring in Thailand, considering the similarity of precipitation characteristic between squalls in Thailand and torrential rainfall in Japan. Based on the results of field monitoring, this study proposes the methodology to investigate numerically the effect of rainfall infiltration into subsoil on slope stability, by focusing on the decrease of shear strength of the unsaturated soil due to increase of volumetric water content at relatively shallow area. The results show that the decrease of shear strength due to rainfall infiltration at the toe portion may become the trigger of shallow landslide.
