大松动圈围岩沿空留巷切顶卸压-恒阻补强分区支护技术

Technology of partition support by cutting-roof pressure relief and constant resistance reinforcement for double-used roadway with deep excavation-induced damage zone

高应力大松动圈围岩运动特征复杂,沿空留巷极易失稳,严重影响工作面推进速度。以顺和煤矿2401工作面运输巷沿空留巷为工程背景,通过对高应力大松动圈巷道围岩破坏特征与失稳原因分析,探究了厚泥岩顶板软岩巷道力学变形机制,对沿空留巷不同段进行了分区划定,提出了基于力学变形机制的围岩控制对策,并进行了工业性试验。结果表明:高应力厚层软岩大松动圈巷道围岩变形破坏主要表现为顶板斜切大面积下沉、两帮非均匀巷内挤出、底臌剪切性错动凸出。高应力环境、厚泥岩顶板大松动圈塑性围岩、巷道围岩非均匀受力与支护体作用失效是巷道围岩失稳的主要原因;顺和煤矿2401工作面沿空留巷为膨胀性-高应力-节理化(HJS型)厚层大松动圈软岩巷道,控制对策力学转化机制为Ⅰ_(C)Ⅱ_(BD)Ⅲ_(BCD)→Ⅱ_(BD)Ⅲ_(BCD)→Ⅱ_(B);将沿空留巷分为超前支护、架后临时支护、成巷稳定3个区域,沿空留巷采用“切顶卸压+恒阻大变形锚索及普通锚索+36U型钢棚”支护方案,分区在方案基础上进行差异化支护;采用新的设计方案后,围岩应力得到释放与切断,补强恒阻锚索与单体支柱控制了巷道围岩变形,U型棚柱腿侧控明显,围岩收敛率小于10%,巷道围岩稳定。

The complex characteristics of the deformation of the surrounding rocks of double-used roadway with deep excavation-induced damage zone and the destabilization of the roadway along the empty stay are very easy,which seriously affect roadway excavation speed.A case study was performed at the headgate of the 2401 longwall panel at the Shunhe Coal Mine.The damage characteristics and destabilization causes of the surrounding rock of the double-used entry were investigated.The mechanical deformation mechanism of the thick mudstone roof soft rock roadway was explored.The zoning of different sections along the roadway was delineated.The control countermeasures of the surrounding rock based on the mechanical deformation mechanism were proposed and implemented at the study site.The results show that the deformation damage of the surrounding rock of the double-used roadway was mainly manifested by the diagonal cutting of the roof with large area sinking,non-uniform in-road extrusion of both sides,and shear misalignment projection of the floor heave.High stress environment,thick mudstone roof,non-uniform stress and support failure were the main reasons for the destabilization of the surrounding rock of the roadway.The roadway was divided into three areas:over-head support area,post-frame temporary support area,and stabilized area.A combined support strategy of"pressure relief through roof cutting+cable bolts+U-shaped steel support"was adopted for the roadway.With this support strategy,the surrounding rock stress was released and cut off.The deformation of the roadway was successfully contained by the cable bolts and the U-shaped steel support.The convergence rate of surrounding rock was less than 10%.