西部高强度开采矿区覆岩破坏发育高度分析

    Analysis of overburden failure development height in high-intensity mining area in Western China

    • 摘要: 导水裂缝带是煤层顶板水害的主要通道,准确预测计算其发育高度是保障矿山安全生产的重要任务。在实测资料的基础上,通过采用理论分析和相似模拟等方法,揭示了西部高强度开采矿区采动覆岩的破坏类型、破坏关系及导水裂缝带的发育特征。结果表明:在薄基岩厚煤层高强度开采条件下,覆岩破坏类型为严重损坏类型。在采动覆岩中只存在“两带”形式,在采空区上方不存在岩层破坏后的具有一定隔水性的弯曲带,导水裂缝带直通地表,地表严重受损。覆岩以组合关键层的形式发生运移。在采动过程中组合关键层以滑落失稳的方式在岩层两端产生切落式破断,导致上覆基岩和松散层切落破断,地表产生台阶状裂缝。地表实测台阶状裂缝沿工作面推进方向的间距与井下周期来压步距相一致。综合考虑覆岩破坏的开采厚度与基岩厚度等关键性因素,提出了高强度开采导水裂缝带发育高度预测计算公式,其可靠性得到了现场实测与相似材料模拟结果的验证,研究结果对于神东矿区煤矿安全开采具有一定的指导意义。

       

      Abstract: Water-conducting fracture zone is the main channel of water damage in coal seam roof. It is an important task to accurately predict and calculate its development height to ensure the safety of mine production. Based on the measured data, the failure types, failure relations and the development characteristics of water-conducting fracture zone of mining overburden in the western high-intensity mining area are revealed by theoretical analysis and similar simulation. The results show that the overlying rock failure type is serious damage type under the condition of high strength mining of thin bedrock thick coal seam. There are only “two zones” in the mining overlying rock, there is no bending zone with certain water insulation after rock failure above the goaf, and the water-conducting fracture zone leads to the surface, causing serious damage to the surface. The overlying rock migrates in the form of assemblage key layers. In the process of mining, the combination of key layers produces shear fracture at both ends of the rock layer by sliding and destabilizing, resulting in the shear fracture of the overburden bedrock and loose layer, and the formation of stepped cracks on the surface. The spacing of the measured step fracture along the advancing direction of the working face is consistent with the pressure step of the downhole cycle. Considering the critical factors such as the mining thickness of overlying rock and the thickness of bedrock, a formula for predicting the development height of water-conducting fracture zone in high-intensity mining is proposed. The reliability of the formula has been verified by field measurement and similar material simulation results. The research results have certain guiding significance for the safe mining of coal mine in Shendong Mining Area.

       

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