近距离煤层遗留煤柱下煤巷位置与围岩控制研究

Study on Determination and Control Technology of Position of Roadway under Left Coal Pilar in Close Coal Seam

以贺西矿近距离煤层开采及下位巷道布置与控制为工程背景,构建力学模型计算得出遗留煤柱底板最大破坏深度为8.38 m,最大破坏深度点与遗留煤柱帮部水平距离为5.24 m;构建数值模型探究3种下位煤巷布置方式下垂直、偏应力分布规律及塑性区分布特征。研究表明:上煤层开采后,采空区端头及煤柱底板分别形成应力降低区、应力骤变区与应力升高区,且随巷道内错距离由大减小,巷道重叠布置及外错布置时,巷道围岩高偏应力场呈现完全对称、非对称及两肩窝集中的现象,巷道内错距离为6 m时,巷道位于卸压区内可有效改善巷道围岩力学环境,同时最大程度回收了煤炭资源。根据研究结果提出高强锚注桁架梁联合支护技术,观测表明,巷道顶底板与两帮移近量最大分别为185、140 mm,有效控制了巷道围岩变形。

Based on the engineering background of the close coal seam mining and the layout and control of the lower roadway in Hexi coal mine,the mechanical model is constructed to calculate that the maximum failure depth of the left coal pillar floor is 8.38 m,and the horizontal distance between the maximum failure depth point and the left coal pillar side is 5.24 m;the numerical model is built to explore the vertical and deviator stress distribution rules and plastic zone distribution characteristics under three types of lower coal roadway layout.The research shows that after the mining of the upper coal seam,the goaf end and the coal pillar floor respectively form a stress reduction area,a stress abrupt change area and a stress rise area,and with the large reduction of the internal staggered distance of the roadway,when the roadway is overlapped and staggered outside,the high deviating stress field of the roadway surrounding rock presents the phenomenon of complete symmetry,asymmetry and two shoulder pits concentration.When the internal staggered distance of the roadway is 6 m,the roadway is located in the relief area,which can effectively improve the mechanical environment of the roadway surrounding rock,at the same time,coal resources are recovered to the maximum extent.According to the research results,the combined support technology of high-strength bolt-grouting truss beam is proposed.The observation shows that the maximum displacement of the roof and floor of the roadway and the two sides are 185 mm and 140 mm respectively,which effectively controls the deformation of the surrounding rock of the roadway.