Failure Mechanism of Underground Mining and Rainfall on High and Steep Slopes in Open Pit Mines: Insights From Model Experiments and Numerical Simulations

ABSTRACT Based on the actual engineering conditions of a mine in Northeast China, this study conducts rainfall model tests on open‐pit mine slopes using a self‐designed model box, coupled with numerical simulations to investigate slope stability under rainfall infiltration. The physical test results reveal that during rainfall infiltration, the displacement in the Y ‐direction is more pronounced than that in the X ‐direction, with such displacements predominantly concentrated on the slope surface. Pore water pressure exhibits a continuous increase as rainfall infiltration proceeds. In the late stage of rainfall, the maximum principal strain is initially concentrated at the slope toe and subsequently propagates toward the middle of the slope. The rainfall infiltration sequence follows a pattern of slope top—slope surface—lower part of the slope mass. Multiple stress mutations occur at various stages of rainfall, inducing further extension of internal cracks within the model and widening of surface cracks due to rainfall erosion. Numerical simulation results indicate that the Y ‐direction strain convergence on the left slope surface presents an arc‐shaped distribution, with an overall increasing trend in strain magnitude. Displacements are mainly concentrated in and around the underground stope, while pore water pressure gradually rises with increasing slope depth. The numerical simulation results are in substantial agreement with those from the physical model tests. The findings of this study provide a scientific reference for the prevention and control of open‐pit slope instability induced by underground mining under rainfall conditions.