回采巷道底板破坏范围及其影响研究

Research on the floor failure range and its effects of entry

针对回采巷道底板破坏深度确定难题,以蒋家河煤矿ZF204工作面运输顺槽为研究背景,采用现场实测、物理相似模拟和数值计算相结合的方法,掌握了巷道两帮脚挤压破碎和底鼓规律,建立了底板破坏力学模型,分析了巷道底板的极限承载力,揭示了巷道底板挤压流动型变形的破坏机理。研究发现,巷道两帮下部的底板极限承载力与内聚力成正比关系,并且随着内摩擦角的增大,巷道极限承载力随内聚力的增大的幅度越大。内聚力一定时,极限承载力随着内摩擦角的减小而降低。围岩渐进破坏参数的折减系数小于1时,极限承载力随着折减系数呈降速减小。基于上述分析,建立了巷道底板极限平衡深度计算模型,得出巷帮极限平衡区宽度与巷道底板破坏深度成线性增长关系,给出了巷道底板最大破坏深度和位置计算公式。基于底板破坏引起极限平衡圈演化研究,完善了巷道支护的极限平衡圈理论。

In order to solve the hard problem of the damage depth determination of entry floor,taking the ZF204 transportation entry of Jiangjiahe coal mine as the background,and using the method of site measurement,physical simulation and numerical calculation,the crushing of two rib feet and floor heave of the entry are obtained,and the deformation and failure mechanism of floor extrusion flow is revealed.The mechanical model of floor failure is established,and the ultimate bearing capacity of the floor is analyzed.The results show that the ultimate bearing capacity of the floor under the two ribs is proportional to the cohesion,and the larger the internal friction angle is,the faster the ultimate bearing capacity increases with the increase of cohesion.When the cohesive force is constant,the ultimate bearing capacity decreases with the decrease of internal friction angle,and decreases rapidly at first,then decreases slowly and tends to be stable.The ultimate bearing capacity decreases in downward velocity when the strength reduction coefficient is less than 1.The calculation model of entry floor limit equilibrium depth is established,and it is concluded that the ultimate equilibrium width of entry rib is linearly related to the failure depth of the floor,the calculation formula of the maximum failure depth and its location of entry are put forward.Based on the research of evolution of limit cycle caused by the floor failure,the limit equilibrium theory of roadway support is improved.