Study on the deformation characteristics of rock mass under the coupling of variable rainfall infiltration-excavation unloading

Heavy rainfall infiltration and complex excavation are two key factors that affect the safety and stability of high and steep rock slopes in mines.To systematically study the evolution characteristics and evolution mechanism of rock mass under the coupling of heavy rainfall infiltration and excavation and unloading, the east Huangniuqian Mining Area of Dexing Copper Mine is taken as the research object.Combined with engineering geological investigation, laboratory rock mechanics test, physical model test of similar materials, MatDEM numerical simulation, theoretical analysis and other means, the failure evolution law of rock mass under the model with a slope height of 200 m and a slope angle of 50° is deeply analyzed.The results show that under the combined action of variable rainfall infiltration and excavation unloading force, the closer to the goaf, the greater the unloading degree of the roof of the stope.Besides, the maximum vertical displacement occurred at the upper boundary of the gob near the toe of the open-pit slope, which is consistent with the numerical simulation results.Specifically, the MatDEM simulated stress changes are larger at the foot of the slope, which is in the shape of alternating wave crests and troughs.Among them, the farther away from the stope, the smaller the influence of rainfall infiltration and mining unloading, and the smaller the unloading degree.The research results can provide effective technical support for complex mining environment.