Model Test Study on Response of Weathered Rock Slope to Rainfall Infiltration under Different Conditions

Weathered rock (especially granite) slopes are prone to failure under the action of rainfall, making it necessary to study the response of weathered rock slope to rainfall infiltration for landslide prevention. In this study, a series of model tests of weathered rock slope under different conditions were conducted. The matric suction, volumetric water content, earth pressure and deformation of slope were monitored in real time during rainfall. The response of the slope to rainfall infiltration, failure process and failure mode of slope under different conditions were analyzed, and the early warning criterion for the failure of weathered rock slope caused by rainfall was studied. The results show that the slope deformation evolution process under rainfall condition was closely related to the dissipation of matric suction. When the distribution of the matrix suction (or water content) of slope met the condition that the resistance to sliding of the slip-mass was overcome, the displacement increased sharply and landslide occurred. Three factors including rainfall process, lithologic condition and excavation condition significantly affect the response of weathered rock slope to rainfall. It can be found from the test results under different conditions that compared with intermittent rainfall condition, the rainfall intensity and infiltration depth were smaller when the slope entering accelerated deformation stage under the condition of incremental rainfall. The accumulated rainfall when weathered clastic landslide occurring was greater than that of weathered granite, which results in greater disaster risk. The excavation angle and moisture distribution of a slope were the main factors affecting the stability of a slope. In addition, the evolution processes and critical displacement velocities of slopes were studied by combining the deformation curves and matrix suction curves, which can be used as reference for early warning of rainfall-induced weathered rock landslide.