巨厚砾岩与逆冲断层控制型特厚煤层冲击地压机理分析

Analysis of rock burst mechanism in extra-thick coal seam controlled by huge thick conglomerate and thrust fault

以某典型冲击地压事故为背景,通过理论研究和现场勘查,研究了巨厚砾岩与逆冲断层控制下特厚煤层工作面冲击地压致灾机理和防治方法。通过对地层结构与开采形成覆岩空间结构的研究,建立了侧向静态支承压力估算模型,得到了21221工作面上覆岩层空间结构与应力分布规律;估算了巨厚砾岩传递应力、自重应力与F16逆冲断层及相变带构造应力的叠加总应力,该应力超过了该矿的临界冲击应力;特厚煤层在叠加应力作用下发生塑性滑移,逐渐形成滑移线场,并产生塑性膨胀,导致巷道围岩应力增加,在外部扰动应力作用下,煤体发生瞬间大范围滑移是发生冲击地压的主要原因。针对这类冲击地压的致灾机理,通过合理设计巷道平面位置以避开传递应力峰值区域、采用半煤岩巷道以减小滑移线场范围和合理设计煤层大直径卸压孔参数以改变煤体滑移方向等措施,有效治理了该类冲击地压。

Through theoretical research and field exploration, the mechanism and control method of rock burst hap- pened in extra-thick coal seam of working face controlled by huge thick conglomerate and thrust fault were studied with typical cases analysis. The calculation model of static side abutment pressure was established through studying the stra- tum structure and overlying strata spatial structure, and the distribution law of the stratum structure and stress of No. 21221 working face. By means of stress superimposing including transmission stress of conglomerate ,in-situ stress and tectonic stress, the final value exceeded the critical stress value inducing rock burst. Under superimposed stress effect, extra-thick coal seam slid and formed slip-line field gradually, and at the same time plastic swelling occurred resulting in stress increase around the roadway, which was the main cause of rock burst occurrence. Aiming to control this kind of rock burst effectively, we can design the position of roadways and the parameters of pressure-relieving boreholes rea- sonably, and adopt mixed coal-rock roadways. The research results were successfully applied to rock burst control inseveral coal mines of Yima.