孤岛工作面开采具有较高冲击风险, 顶板预裂是一种有效的减冲技术。以高庄煤矿3_上1105孤岛工作面为背景, 通过理论分析、数值模拟和现场实测等手段, 研究了孤岛工作面冲击致灾机理、顶板预裂减冲机制及其影响因素。研究结果表明, 两侧采空区覆岩形成的多拱结构传递压力及“砌体梁”结构失稳诱发强动载是孤岛工作面高冲击风险主要原因; 建立了局部压力拱结构力学模型, 分析局部压力拱力学特性, 给出了局部压力拱失稳判据; 顶板预裂爆破方法减冲机制为通过破坏形成局部压力拱的“砌体梁”结构, 阻断压力传递路径, 降低高支承压力场, 减小开采期间“砌体梁”失稳诱发强动载风险。现场微震实测数据表明, 顶板预裂减冲效果较好, 有效降低了冲击风险。

Mining in island working faces poses a high risk of rock bursts, and roof pre-cracking is an effective mitigation technique. This study investigates the No.1105 island working face in the upper coal seam 3 of Gaozhuang Coal Mine. Using theoretical analysis, numerical simulations, and on-site micro-seismic monitoring, the mechanism of rock bursts in island working faces was analyzed, and the effectiveness of roof pre-cracking in reducing rock burst risk was assessed. The results show that the multi-arch structure formed by overburden rock in the adjacent goaf areas facilitates pressure transmission, while the instability of the "voussoir beam" structure induces strong dynamic loads, which are the primary causes of the high rock burst risk. A mechanical model for local pressure arches was established to analyze their mechanical properties, and instability criteria were derived. The roof pre-cracking blasting method reduces rock burst risk by destroying the local pressure arch structure and disrupting the "voussoir beam". This disruption obstructs the pressure transmission path, reduces the high bearing pressure zone, and minimizes the risk of strong dynamic loads caused by beam instability during mining. On-site micro-seismic monitoring data confirm the effectiveness of roof pre-cracking, demonstrating a significant reduction in rock burst risk.