西部矿区覆岩-煤柱群失稳临界时间节点研究

Critical failure time of roof and standing pillars in China western mining area

为分析覆岩-煤柱群回收前的稳定性,采用数值模拟软件Flac3D分析了煤柱蠕变期间塑性区发育及内部应力分布形式的演化特征,发现:蠕变过程分为快速变形、缓慢变形及加速失稳3个阶段,并总结出了不同阶段塑性区发育和内部应力分布形式的对应关系;在分析覆岩和煤柱相互作用的基础上,建立了弹性地基薄板模型,推导出了顶板变形、煤柱受力与煤柱塑性区发育范围之间的计算方程组,揭示了覆岩-煤柱群减弱至失稳的动态变化特征;给出了覆岩-煤柱群体系失稳临界时间节点判据和方法,并结合工程算例进行了分析。

Stress and displacement field of roof and standing pillars（ RSP） are always in a state of flux,its stability should be studied before recovering the standing pillars. The creep process of coal pillars is analyzed by Flac3 D. The process could be divided into three stages： rapid deformation,slow deformation and accelerating failure. Also,the laws of plastic zone and inner stress distribution pattern of coal pillars at different stages are obtained. Based on the theoretical analysis,one thin plate on elastic found model is established to analyze the relationship between the roof deformation,the force on the pillars and the ranges of plastic zones of coal pillars,and the proposed model allows to reveal the dynamic evolution of the decreasing-failure process of RSP. Furthermore,a criterion for evaluating the critical failure time of RSP is then given in this study,which is illustrated through an engineering case.