房柱式采空区顶板破坏失稳机理研究

Study on failure and instability mechanism of roof in room-and-pillar goaf

针对房柱式采空区失稳致灾问题,以榆林某矿房柱式采空区遗留煤柱为研究背景,采用理论分析、物理相似模拟、数值分析等研究方法,对房柱式采空区顶板失稳机理进行研究。研究结果表明:矿井采空区遗留煤柱稳定性安全系数为1.54,考虑煤柱在顶板长期载荷作用下发生蠕变作用,最终会发生大面积失稳;房柱式采空区煤柱破坏失稳诱灾影响因素包括煤体物理力学性质、风化作用、开采方式、积水浸蚀、蠕变作用等5种因素;房柱式采空区顶板灾变演化为“由点及面”的破坏规律,顶板由破坏到失稳分为初步破坏阶段、破坏扩展阶段、破坏加剧阶段及彻底失稳阶段4个阶段;采空区彻底失稳时煤柱应力峰值为15.08 MPa,应力集中系数为3.92,顶板下沉位移为392.44 mm。

In view of the disaster caused by the instability of room-and-pillar goaf,taking the coal pillar left over from a pillar goaf in Yulin as the research background,the roof instability mechanism of room-and-pillar goaf is studied by means of theoretical analysis,physical similarity simulation,numerical analysis and so on.The research results show that the safety factor of the stability of the remaining coal pillar in the mine goaf is 1.54,considering the creep of the coal pillar under the long-term roof load,the large area instability will occur in the end.The influencing factors of the failure and instability of the coal pillar in the room-pillar goaf include five factors,such as physical and mechanical properties of coal,weathering,mining mode,water erosion,creep and so on.The failure law of the catastrophic evolution of roof in room-and-pillar goaf is from point to surface,and the roof from failure to instability is divided into four stages:preliminary failure stage,failure expansion stage,failure aggravation stage and complete instability stage.When the goaf is completely unstable,the peak stress of coal pillar is 15.08 MPa,the stress concentration factor is 3.92,and the roof subsidence displacement is 392.44 mm.