降雨-地震耦合作用下含断裂边坡动力特性研究OACHSSCD

Steep slopes containing fault zones are widely developed in the Dadu River basin on the eastern margin of the Tibetan Plateau,where large landslides occur frequently under the combined effects of strong earthquakes and rainfall,posing severe threats to the safety of infrastructures along the corridor.Taking the Mogangling landslide in this region as the case study,this paper establishes a numerical model of a steep slope with a fault zone and investigates the dynamic characteristics under two loading scenarios,namely seismic loading and rainfall-earthquake coupling,using numerical simulation and shaking-table tests,with the seismic test results used to validate the numerical model.The results show that under seismic loading,the horizontal acceleration generally increases with elevation,whereas a pronounced local amplification occurs at the fault-zone elevation.The potential sliding structure remains in a critical stability state,and the surface displacement response and the elevation-dependent amplification of peak horizontal acceleration exhibit broadly consistent trends between the numerical and experimental results.Under intense rainfall,a high-infiltration and high-pore-pressure zone develops near the ground surface within the strongly weathered granite and the fault fractured zone,reducing the effective stress around the hanging wall of the fault zone and near the boundary between strongly and moderately weathered granites,and causing infiltration-induced pre-weakening prior to the earthquake.After seismic input,the high pore-pressure region spatially overlaps with the high-acceleration and high cyclic stress ratio regions,which promotes the concentration of shear deformation and rapid expansion of the plastic zone,indicating a cascading failure process characterized by rainfall pre-weakening,earthquake triggering,and re-amplification of the dynamic response.The critical slip surface extends along the boundary between strongly and moderately weathered granites,is controlled by tensile cracking in the upper part,and shears out from the fault zone at the leading edge.Rainfall markedly advances the earthquake triggering threshold and aggravates the risk of cascading failure.This study can provide reference for risk mitigation of fault-controlled steep slopes in alpine canyon regions.