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垮落带内含有厚层坚硬岩层时,难以冒落,易在沿空巷道采空区侧形成弧形三角悬板,对沿空巷道产生较大压力。以大同唐山沟8820厚层砂岩顶板首采面无煤柱开采为背景,分析普通充填留巷和切缝沿空成巷侧向顶板断裂结构特征及围岩稳定过程,认为对垮落带内直接顶坚硬层顶板进行合理参数下的切缝,可使得切缝高度范围内采空区边界直接顶和基本顶失去约束,并沿切缝结构面剪切破断充分冒落接顶,降低破断冲击动载;并通过UDEC数值模拟软件,分析出切缝有利于矸石冒落并支撑上覆岩层,可将上覆基本顶岩层的触矸点前移,限制基本顶回转和下沉作用引起的围岩压力,明显减小巷道围岩变形量。基于理论、数值分析研究结果,确定唐山沟矿8820回风巷巷内加强巷旁密集支柱+巷旁双向聚能爆破切缝的上压下支中间切缝的联合切顶方案。通过井下爆破参数试验、矿压监测分析,评价切顶成巷的效果。井下试验表明:顶板高恒阻大变形锚索、巷内加强巷旁密集支柱、巷旁密集档矸点柱、超前聚能切缝爆破的切顶成巷综合技术,能够有效切落沿空巷道侧向顶板并形成完整巷道,各项指标均满足下一工作面回采要求。
When the caving zone contains thick hard rock formations, it is difficult to fall off, forming arc-shaped triangular suspension panels on the goaf side of the gob in the gob along the gondola, causing great pressure on the gob-side entry. Taking the coal mining in the first mining face of 8820 thick sandstone roof in Tangshan Ravine, Datong, as the background, the structural characteristics of lateral roof fracture and the stability of surrounding rock during the process of filling roadway along gob-side entry of karst seam are analyzed. Under the reasonable parameters, the top hard layer roof can make the direct top and the basic top of the gob boundary within the height of the kerf cut off the constraint, and cut and cut along the kerf structure surface to fully take off the roof so as to reduce the breaking impact Based on the UDEC numerical simulation software, it is analyzed that the kerf is favorable for the gangue to fall off and support the overlying strata, and the rock contact point of the overlying basic roof strata can be advanced to limit the surrounding rock caused by the basic top turning and sinking Pressure, significantly reducing the deformation of roadway surrounding rock. Based on the results of theoretical and numerical analysis, the joint cut-top scheme for strengthening the roadway dense pillars + the double-side converging blasting in the tunnel of Tangshangou 8888 return airway is established. By downhole blasting parameters test, rock pressure monitoring analysis, to assess the effect of cut into the lane. The downhole tests show that the technology of roof top with high constant resistance and large deformation anchor cable, laneway intensive pillar in lane, dense pillar of roadway beside pillar, and cutting edge into lane with advanced cutting edge can effectively cut down the sideways Roof and form a complete roadway, the indicators meet the requirements of the next face mining.