采空区下近距离煤层巷道围岩稳定性分析及控制

针对近距离煤层工况条件下，下部特厚综放工作面开采时存在覆岩应力变化大、矿压显现明显、工作面支护难度加大，煤壁片帮、顶板漏冒事故多等问题，以王庄煤矿开采的2号和3-5号煤层工作面为工程背景，通过理论分析、采用UDEC离散元软件和FLAC 3D软件建模分析及现场应用实践等方法，对近距离特厚煤层开采条件下工作面采空区覆岩运动及顶板应力变化规律进行了研究分析。结果表明，上部2号已开采煤层覆岩关键层岩体发生断裂对下部3-5号煤层工作面来压强度影响巨大，容易引发工作面采空区顶板大面积来压。据此提出优化30501工作面巷道布置，将原回风巷向内侧偏移25.4 m，工作面倾斜长由原来的180 m缩短为154.6 m，从而减小上部煤层工作面留设的区段煤柱应力影响范围，同时通过优化工作面开采工艺、合理确定工作面三机设备选型和端头及超前支护方案。现场应用结果表明，工作面在掘进和回采过程中矿压显现程度及次数明显降低和减少，未发生过顶板、瓦斯等大型事故，实现了安全高效回采。

Stability analysis and control of surrounding rock in short distance coal roadway under goaf

In view of the problems existing in the mining of the lower extra thick fully-mechanized top coal caving face under the working condition of short distance coal seam，such as large variation of overburden stress，obvious ground pressure appearance，increased difficulty of working face supporting，and many accidents of coal wall caving and roof leakage，taking the working faces of No.2 and No.3-5 coal seams mined by Wangzhuang Coal Mine as the engineering background，through theoretical analysis,using UDEC discrete element software，FLAC 3D software modeling analysis and field application practice，this paper studied and analyzed the overburden movement and roof stress change law in the goaf of the working face under the condition of short-range extra thick coal seam mining.The results showed that the fracture of the rock mass of the key overburden layer of the upper No.2 mined coal seam has a great impact on the compressive strength of the working face of the lower No.3-5 coal seam.It is easy to cause a large area of roof pressure in goaf of working face.Therefore，it was proposed to optimize the roadway layout of 30501 working face，offset the original return air roadway to the inner side by 25.4 m，and shorten the inclined length of the working face from the original 180 m to 154.6 m，so as to reduce the influence range of section coal pillar stress left in the working face of the upper coal seam.At the same time，through optimizing the mining technology of the working face，reasonably determined the selection of three machine equipment and the end and advance support scheme of the working face.The field application results showed that the degree and times of ground pressure manifestation in the process of heading and mining are significantly reduced，and there have been no large accidents such as roof and gas，so as to realize safe and efficient mining.