Numerical analysis of the dynamic evolution of mining-induced stresses and fractures in multilayered rock strata using continuum-based discrete element methods

In this study, the continuum-based discrete element method (CDEM) was adopted to simulate the evolution of mining-induced stress and fracturing during roadway tunnelling and mining in multilayered heterogeneous rock strata. The CDEM integrates the finite element method (FEM) and the discrete element method (DEM) to characterize the mining-induced stress evolution, the discontinuous fractures, separations, and caving that occur in the interfaces between multilayered rock strata. The maximum tensile-stress criterion and the Mohr-Coulomb strength criterion were used to evaluate the tensile and shear failure of the material elements. The CDEM model for rock strata was constructed by employing image processing and reconstruction approaches, using the geometrical and physical parameters that were measured from a real coal mining site. The stress evolution and compression deformation of the roof and floor strata were computed to evaluate the criticality of mining-induced disasters. The constructed model was employed to simulate and analyse the immediate roof collapse, immediate floor bulges, and the compaction of the collapse blocks, as well as the large deformation, separation, and collapse between the immediate roof and the main roof during coal seam mining. It was shown that the proposed method could predict ranges for the caving zone and fracture zone in the rock roofs that were in good agreement with the observation results from the real coal mining site