倾斜煤层沿空异形巷道煤柱宽度与围岩控制研究

Study on reasonable coal-pillar width and surrounding-rock control of gob-side irregular roadway in inclined seam

为了探究倾斜煤层沿空掘巷留窄煤柱的合理宽度,采用传统矿压"内外应力场"理论和偏应力第二不变量表征特性对不同宽度煤柱影响下巷道围岩破碎机理与控制展开研究。通过建立沿空斜顶巷道力学模型,推导出倾斜煤层"内应力场"影响范围为12.2～12.8 m。与水平煤层不同,倾斜煤层巷道顶板围岩在一定深度开始受到其相邻采空区应力影响,引起偏应力值再次攀升,计算应力波动值结合巷道围岩位移变化情况,最终确定合理窄煤柱宽度为10 m。异形巷道断面特征导致围岩应力分布和破碎呈现不对称性,继而提出顶板预应力锚杆+高强度单体锚索+桁架锚索支护耦合作用下的非对称围岩控制技术,最后经50 m试验段作为工程检验,成功应用于工程现场。

To determine the reasonable narrow coal pillar width of gob-side entry in inclined coal seam, the surrounding rock fragmentation mechanism and control techniques corresponding to different coal-pillar widths were investigated by adopting the theory of "internal and external stress field" and second invariants characterization of deviatoric stress. The results show that the influence range of "internal stress field" in inclined coal seam is 12.2-12.8 m based on analyzing the mechanical model of gob-side roadway. Compared with the horizontal coal seam, the surrounding roof rock of roadway in the inclined coal seam is affected by the stress of adjacent goaf area at a certain mining depth, which causes the deviatoric stress value to rise again. By calculating the influences of stress-wave value and displacement changes of roadway surrounding rock, the reasonable coal-pillar width is determined to be 10 m. The cross-section characteristics of irregular roadway lead to the asymmetry of stress distribution and fractures. Therefore, the asymmetric surrounding rock control technology in inclined coal seam is put forward. This technology applies to the coupling effects of high strength prestressed anchor bolt &high strength single body anchor cable & truss anchor support. Above technique has been successfully applied to the engineering site, with a 50 m long test section.