Mechanism of rainfall-induced shallow landslide and stability prediction model

The rainfall-induced shallow landslides are primarily debris landslides, which features simultaneity with significant hazard, and the hydrological response mechanism of water table and soil moisture content to precipitation of this type of landslide is sophisticated, which makes it difficult to predict the slope stability accurately. To further study the influence of the rainfall-triggered internal hydrological responses on slope-stability, on-site precipitation infiltration monitoring, correlation analysis and mechanical analysis were carried out on the Houshanli landslide in Qingchuan County, Sichuan Province. The relationship between precipitation and water table was proposed based on climate and hydrological monitoring data obtained within three year interval. The response of rainfall infiltration, soil volumetric water content and water table were analyzed. The results indicate that: (1) groundwater exhibits periodic fluctuations throughout the year, characterized by three phases of slow decline, rapid decline, and rapid ascent; a linear negative correlation between precipitation and water table was found, and no significant correlation was observed with the water table increment; (2) through the infinite slope model and the relationship between precipitation and water table, a prediction model for shallow landslide stability was constructed. The precipitation threshold (81.8 mm/d) and water table threshold (0.73 m) were determined which has good agreement with the actual situations. This provides an early warning method for rainfall-induced shallow landslides by monitoring these two factors.