深部“三面”孤岛工作面采动覆岩变形特征研究

Research on deformation characteristics of mining overburden rock on deep "three-sided" island working face

为研究左、右、上三面均存在老采空区的深部“三面”孤岛工作面回采过程中覆岩变形破坏特征,以某煤矿120502工作面为研究对象,利用FLAC3D模拟软件对回采过程中覆岩应力、位移和塑性区变形特征进行了系统的数值研究。结果表明:左、右、上三面均存在老采空区的“三面”孤岛工作面在回采过程中主要受上部老采空区扰动,倾向上左侧煤柱应力集中程度较高,走向上工作面前方的垂直应力先降低后不断升高,应力集中系数不断增大;垂直位移的方向由向下转变为向上,向下的垂直位移峰值不断增大,但向上的垂直位移峰值保持稳定;塑性区的破坏范围呈现“马鞍形”,逐渐扩大与临近3个老采空区塑性区相互贯通,且顶板上方岩体处于拉压应力区,采空区围岩裂隙发育更为充分;临近老采空区和卸压煤体内的瓦斯均向开采层采空区流动,应重点加强该工作面采空区内的瓦斯抽采工作。

In order to study deformation and failure characteristics of mining overburden rock on the deep "three-sided" island working face with old goaf on the left,right and upper sides,taking 120502 working face of a coal mine as research object,the stress of overburden rock,displacement and deformation characteristics in plastic zone in the mining process were systematically and numerically studied using FLAC 3D simulation software.The results show that in the stoping process,the "three-sided" island working face with the old goaf on the left,right and upper sides is mainly disturbed by the upper old goaf,and stress concentration of left coal pillar in the prone direction is higher,the vertical stress in front of working face on strike direction decreases first and then increases continuously,and the stress concentration factor increases continuously.The direction of vertical displacement changes from downward to upward,and the downward vertical displacement peak increases continuously,but the upward vertical displacement peak remains stable.The damage range of plastic zone appears "saddle shape",and gradually expands to be connected with the plastic zone of the adjacent three old goafs,and the rock mass above the roof is in the tension-compression stress zone,and the cracks in the surrounding rock of the goaf are more fully developed.The gas near the old goaf and the pressure-removing coal body flows to the goaf in the mining layer,so the gas drainage work in the goaf of the working face should be emphasized.