Collaborative movement characteristics of overlying rock and loose layer based on block–particle discrete-element simulation method

Abstract A novel block–particle discrete-element simulation method that matches the double medium of overlying rock (OLR) and loose layer (LSL) in coal mining is developed in this study. This method achieves the collaborative failure characteristics of mining damage under the conduction of double media between the OLR and LSL by combining the self-weight stress loading of the LSL and the breakage morphology of the bedrock top. Based on this, the conduction law of high-strength mining damage in the double medium in a western mining area is simulated and analyzed. The combining effect of the OLR breakage morphology and LSL characteristics on the surface-subsidence characteristics is analyzed and verified based on on-site measurements. The results indicate that the OLR is guided by the “double-control layer and thick-soft rock buffer layer” and shows “grouping subsidence”, whereas the surface forms collaborative subsidence with the thick-soft rock buffer layer. In the ultra-full mining stage, the surface presents an “asymmetric inverted trapezoidal” subsidence trough shape. The simulation results agree well the on-site measurements in terms of the surface-subsidence and bedrock-subsidence coefficients. The proposed simulation method provides a scientific approach for investigating the micro-conduction mechanism of mining damage under the effect of high-strength mining in western mining areas. It will benefit future investigations pertaining to the characteristics of OLR breakage and surface subsidence under conditions such as LSL thickness and proportion.