高应力“三软”煤层回采巷道围岩破坏机制及控制研究

Mechanism and control of failure for surrounding rock in highly stressed “three soft” coal seam mining roadway

为明确高应力"三软"煤层回采巷道围岩破坏模式和支护失效机制,以船景煤矿典型"三软"不稳定煤层1171综采工作面回采巷道为工程背景,通过室内及现场实验、现场观察监测和理论分析相结合的方法对巷道围岩变形破坏进行综合分析研究。结果表明:巷道围岩破坏模式为高应力条件下的软岩流变大变形破坏模式;支护失效机制为高应力条件下软弱围岩在流变作用下松动破坏扩展剧烈,致使锚网索联合支护结构失效,进而导致围岩-支护承载结构丧失承载力;对于高应力"三软"煤层回采巷道,锚网索联合支护具有明显的局限性。最后提出以新型全长黏结锚固、全封闭护面、顶板多拱有序承载和围岩协同加固技术为核心的优化支护方案并在现场实验应用,结果显示优化支护段巷道围岩变形得到有效控制。

To find out the failure mode of surrounding rock and the supporting failure mechanism of mining roadway in highly stressed ＂three soft＂ coal seam, taking the typical mining roadway of No.1171 fully mechanized mining face in ＂three soft＂ and unstable coal seam of Chuanjing mine as the engineering background, using the laboratory and field experiments, the in-situ monitoring and theoretical analysis are synthetically used to analyze the surrounding rock deformation and failure, results show that the failure mode of surrounding rock is rheological soft rock with large deformation subject to the high stress; the supporting failure mechanism is that the highly stressed weak surrounding rock causes loosening damage dramatically under the effect of rheological behaviors, this leads to the failure of combined bolting with wire and cable anchor, and then the rock-support bearing structure lose its capacity. It also shows that the support with combined bolting with wire and cable anchor was found to have limit effect in the ＂three soft＂ coal seam mining roadway. Instead, a new optimization design of support scheme with the core of full-length bonding anchorage, fully-closed working face, multi-arch roof ordered bearing and surrounding rock cooperative strengthening is introduced and applied in the field. The result shows that it had great effects on the stability control of surrounding rock.