Study on Mechanism and Prevention of Seismicity Caused by Fracture of Extra-Thick Strata at High Position

Mining-induced seismicity caused by the fracture of extra-thick strata at high position (ETSHP) presents significant challenges in both prevention and control. This study combines theoretical analysis, numerical simulations and field data to explore the mechanisms behind seismic events induced by ETSHP during coal extraction and the mechanical interactions between ETSHP and the mining-induced "two zones" (the fractured zone and bending subsidence zone). The interaction between ETSHP and underlying strata was modeled using Reissner-Mindlin plate theory, with elastic energy calculations to predict the formation and evolution of separation spaces between ETSHP and overlying strata. The key influencing factors such as coal seam thickness, the spacing between coal seam and ETSHP, and the size of the goaf were examined. Results indicate that thinner coal seams, larger coal-rock spacing, and greater goaf lengths lead to larger separation spaces, significantly increasing the risk of mining-induced seismicity. Additionally, the study developed a comprehensive control strategy combining deep-hole roof blasting and surface hydraulic fracturing to mitigate seismic risks. The effectiveness of these techniques was validated through field monitoring, revealing their ability to reduce seismic hazards in mining operations. This research provides theoretical and practical guidance for managing seismic risks in similar conditions.