Evolution of mining-induced stress and strata control in underground coal mines

Stress is the fundamental driving force causing deformation and damage of the surrounding rock in mining engineering underground spaces. Widespread and highly concentrated stress is a notable feature of mining-induced stress in underground coal mines. The stress field underground in coal mines includes the in-situ stress field，mining-induced stress field，and support stress field，together forming the comprehensive underground stress field. This article discusses the stress evolution characteristics of coal mine surrounding rock and the theory and technology of surrounding rock control，with stress as the main focus. Regarding in-situ stress，based on extensive field measurements of in-situ stress，the distribution characteristics and influencing factors of the underground stress field in Chinese coal mines were detailedly analyzed. Concerning mining-induced stress，a combination of theoretical analysis，numerical simulation，physical simulation，and field monitoring methods were employed. The evolution process of stress in the excavation face and roadway surrounding rock was comprehensively studied from multiple perspectives，and the mining-induced stress evolution characteristics and main influencing factors around the coal mining face were analyzed. In terms of support stress ， a series of roadway support test and simulation experiment platforms were independently developed. Systematic tests were conducted on rock bolts and roadway surface protective components under various complex load conditions，and their mechanical response characteristics and failure mechanisms were evaluated. The distribution characteristics and evolution laws of the support stress fields generated by various support methods，both in support itself and in the surrounding rock，were deeply studied. Based on the studies of in-situ stress，mining-induced stress，and support stress，the control mechanisms，design methods，support reinforcement materials，and control techniques of rock surface support，anchoring，modification，unloading，and combined methods were analyzed. Application examples emphasized hydraulic fracturing unloading technology and the synergistic control technology of support+modification+destressing. Underground tests and applications showed that the surrounding rock control technology based on mining-induced stress evolution significantly improved the stability and safety level of the roadway surrounding rock，achieving good rock control effects. Finally，the challenges in the study of underground stress fields in coal mines and the control of roadway surrounding rock were analyzed，and the future trends in surrounding rock stress testing and analysis，and the theory and technology of surrounding rock control were discussed. © 2024 Academia Sinica. All rights reserved.