特厚煤层回采巷道底鼓力学特性及控制研究

Study on mechanical properties and control of floor heave in mining roadway of extra-thick coal seam

针对特厚煤层回采巷道底鼓难以治理的难题,以陕西陕煤曹家滩矿业有限公司(以下简称“曹家滩煤矿”)122110回采巷道作为研究背景,通过现场观测得到特厚煤层回采巷道围岩变形特征,采用理论分析的方法研究区段煤柱上覆关键层破断结构及巷道底鼓机理,通过数值模拟的方法得到底鼓控制措施。研究表明,巷道两侧非对称集中应力导致底板产生非对称底鼓,特厚煤层回采覆岩破断形成不同的承载结构。基于关键层破断特征构建了特厚煤层“下位台阶上位铰接”结构力学计算模型,得到区段煤柱上方载荷计算式;根据滑移线理论建立了巷道非对称底鼓的力学模型,得到了底板破坏深度及位置计算式。由理论计算和数值模拟,得出切槽卸压的底鼓治理措施并计算了切槽参数。通过在曹家滩煤矿现场试验表明,采用3 m×0.5 m(深×宽)切槽方案后,底板平均底鼓量为128.4 mm,较未切槽前减小了81.8%,能够满足综放工作面正常回采需求,可为类似地质工况条件提供参考。

Aiming at the problem that it is difficult to control the floor heave of the mining roadway in extra-thick coal seam,taking the 122110 mining roadway of Shaanxi Shanmei Caojiatan Mining Co.,Ltd.(hereinafter referred to as“Caojiatan Coal Mine”)as research background,the deformation characteristics of the surrounding rock of the mining roadway in the extra-thick coal seam were obtained through field observation,the theoretical analysis method was used to study the fracture structure of the overlying key layer of sectional coal pillar and the mechanism of the floor heave of the roadway,and the floor heave control measures were obtained by numerical simulation.The research showed that the asymmetric concentrated stress on both sides of the roadway led to the asymmetric floor heave and different bearing structures formed from the fracture of the overburden rock in the extra-thick coal seam.Based on the fracture characteristics of the key strata,the mechanical calculation model of the“lower bench-upper hinge joint”structure of the extra-thick coal seam was constructed,and the load calculation formula above the sectional coal pillar was obtained.According to the theory of slip line,the mechanical model of asymmetric floor heave of roadway was established,and the calculation formula of floor failure depth and position was obtained.The floor heave control measures of grooving and pressure relief were obtained by theoretical calculation and numerical simulation,and the grooving parameters were calculated.The field test showed that the average floor heave was 128.4 mm after adopting the 3.0 m×0.5 m(deep×wide)grooving scheme,which was 81.8%lower than that before the grooving.It was showed that the control measures could meet the normal mining of the working face and provide a reference for similar geological conditions.