The Combined Effect of Stress Mutation and Displacement Evolution on Overlying Rock Collapse From Physical Experiment and Numerical Simulation Study

Abstract

This study investigates the complex failure mechanisms of overlying strata deformation induced by longwall mining, with a focus on the 21221 mining face in Qianqiu mine. Combining physical similarity simulation and numerical analysis, the research analyzes the abrupt changes in stress and displacement within the overlying rock mass during mining face advancement. The results show that roof failure occurs periodically, with collapse height and area progressively increasing as the intact bearing zone shifts upward, exerting continuous pressure on the stope. Mining disturbance significantly affects the roof ~40 cm ahead of the working face, where deformation and collapse are governed by gravitational forces and rock lithology. The maximum principal stress concentrates at the goaf edges, and vertical stress mutation accurately indicates impending roof fracture locations. Critically, the failure of hard conglomerate layers triggers a strong regional mutation in the mining-induced stress field. These results provide important insights into the dynamic evolution and instability precursors of overlying strata in deep mining conditions.