Abstract: Through field investigation and statistics of more than 100 landslides in Nanjiang county, the Erhuang ping landslide was selected as a case study to reveal the formation mechanism of and rainfall infiltration in soil landslide. Through analyzing multiple factors including precipitation, accumulative displacement of GPS, pore-water pressure and moisture content of soil, the process of rainfall infiltration of Erhuangping landslide was simulated by finite element analysis. Results showed that the variations of pore-water pressure and soil moisture of shallow soil in the landslide lagged obviously in the initial stage of rainfall precipitation. The main infiltration direction was perpendicular to the surface of slope, and then changed to be along the slope direction. As a water-storing boundary was formed by the cohesive accumulation body, steep side cliff and bedrock surface, pore water pressure in the front edge of slope was more sensitive to rainfall than that in the rear edge does. Due to the anisotropy of slip mass, local pore water pressure and seepage force rises sharply during rainfall, and the soft clay softened, finally resulting in the global instability of slope.

Key words: shallow soil landslide, infiltration of rainfall, deformation monitoring, formation mechanism, pore water pressure