厚煤层综放沿空留巷“支-卸”协同围岩控制技术

A"support and pressure relief"ground control technology for double-used roadway with fully-mechanized caving method in thick coal seam

为了解决高瓦斯厚煤层条件下综放工作面沿空留巷围岩变形严重、支护难以满足留巷要求等问题,以野川煤矿3号煤层3203工作面围岩地质条件为背景,通过围岩结构和受力特征分析,提出了包括“巷内采用高强度锚索合理补强支护,高强度、高刚度、高延性巷旁支护,改造顶板结构,改善留巷应力环境”的“支-卸”协同沿空留巷围岩控制对策。采用“高强度走向交叉锚索梁+高强度、高刚度、高延性新型内外约束混凝土巷旁支护墙体+短孔水力压裂初采切顶卸压+定向水平长钻孔区域卸压”的“支-卸”协同沿空留巷围岩控制技术方案,实现了高位瓦斯抽放钻孔“一孔两用”,并进行了工程实践和矿压观测。观测结果表明:“支-卸”协同围岩控制技术显著改善了沿空留巷围岩应力环境,留巷断面收敛率约13%,墙体最大横向载荷60 kN,有效控制了厚煤层沿空留巷围岩变形,保证了墙体稳定性;复用期间巷道超前20 m范围内围岩变形量均小于60 mm,墙体稳定性良好,满足复用要求。同时,厚煤层综放沿空留巷“支-卸”协同围岩控制技术在现场的成功应用,也为其他条件下有效控制沿空留巷围岩变形提供了一种新的思路和方法。

Double-used entries generally experience severe deformations,expecially under the condition of mining a thick coal seam with rich methane using full mechanized caving method.A case study was performed at the 3203 longwall face of Yechuan Coal Mine.Through the analysis of the structure and stress characteristics of the surrounding rocks,the"support and pressure relief"coordination surrounding rocks control measures were proposed.The measure adopts high strength rock cable for rock reinforcement and high strength and high stiffness roadside support with high extensibility for rock roof support.It also involves improving the adverse geological conditions of the entry.A combined support strategy of high-strength directional cross cable beam+new internal and external restrained concrete roadside support packages+pressure relief through hydraulic fracturing was proposed for the ground support of the double-used entry.Field observation shows that the proposed strategy has significantly improved the stress environment of the surrounding rocks of the double-used entry.The deformation rate of the entry was about 13%,and the maximum horizontal load of the side wall was 60 kN,which was much less than the yield load of the contrete packages.The deformation of the entry during the second longwall mining was less than 60 mm in the range of 20 m ahead.The proposed support stragey provide effective alternative for ground control of double-used entries under similar conditions.