Field Experiments of Rainfall‐Induced Weathered Granite Residual Soil Shallow Landslides

Affected by the extreme climate in recent years, the heavy rainfall has induced a large number of shallow landslides along roads in the granite residual land area in southeast China. Currently, the hydraulic response, evolution mechanism, and failure process of unsaturated granite residual soil landslides at the field scale are not well understood. A small‐scale field experiment was conducted in Beiliu City, Guangxi Province, southwestern China. The soil moisture and pore water pressure were monitored across the slope. According to results from several sensors, the surface infiltration process and deformation characteristics of the unsaturated granite residual soil slope were revealed. The moisture content and pore pressure present were drastically different when slope failures occurred. The pore water pressure at the slope toe was the largest; the pore water pressure in the upper layer was less than that in the lower layer. Four failure stages were identified during the experiment, including the rapid saturation stage, local deformation stage at the slope toe, shallow instability stage, and overall failure stage. This study can help engineers gain more insights into the failure mechanism of the granite residual soil slopes under heavy rainfall.