基于上覆巷道保护的下伏煤层安全回采

Mining safely under a coal seam while protecting an overlying roadway

  • 摘要: 针对千米深井下伏煤层回采需保证上覆巷道稳定性的问题,通过理论分析、数值模拟和现场实测的方法,研究了下伏煤层开采过程中上覆岩层巷道变形破坏类型、破坏机理和防治办法。通过对开采条件和开采形成的覆岩空间结构的研究,得到了走向和倾向方向上的巷道变形破坏规律;通过研究下伏工作面不同开采阶段、不同充填率条件对上覆巷道的采动影响,得到了巷道变形破坏的应力演化规律。结果表明:千米深井下伏煤层开采,上覆巷道潜在的变形破坏类型主要有两种,一是巷道断面缩减型破坏,二是巷道走向阶梯下沉型破坏。上覆巷道变形破坏的根本原因是大埋深、强采动应力,特别是下伏煤层距上覆巷道较近且距离不均等的影响,直接原因是采动造成的巷道围岩应力突增及关键岩层的破断下沉。开采过程中,工作面走向开采范围超过400 m时,巷道断面缩减型破坏和走向阶梯下沉型破坏会相互叠加,诱发更大的巷道破坏。为控制这两种巷道的潜在破坏类型,设计了沿工作面下部巷道动态部分充填和巷道补强支护方案,通过现场实测发现上述方案能够满足上覆巷道稳定性和下伏工作面高效高产的要求,研究结果和控制方案可为千米深井巷道下压煤的安全回采提供一定的借鉴。

     

    Abstract: To ensure the stability of an overlying roadway in close proximity to a 1000-m deep coal seam, this work, through theoretical analysis and numerical simulation, studies the deformation and failure mechanism, failure types, and prevention methods of the overlying roadway while mining a lower coal seam. Based on the study of mining conditions and overburdened space structures formed through mining, the deformation and failure law of the roadway in the strike and dip directions is obtained. Moreover, the stress evolution law of roadway deformation and failure is obtained by studying the influence of different mining stages and filling rates of the lower face on the mining of the overlying roadway. Results show that there are two types of potential roadway deformation and failure: (1) roadway section reduction failure and (2) roadway strike step subsidence failure. The fundamental cause of the deformation and failure of the overlying roadway is the influence of the large buried depth, strong mining stress, and unequal distance between the coal seam and roadway. The direct causes are the sudden increase in the stress of the roadway surrounding the rock and the subsidence of the key strata. In the mining process, when the mining range of the working face is more than 400 m, the roadway section reduction failure and strike ladder subsidence failure superimpose each other, inducing further roadway failure. Therefore, a scheme of partial filling and strengthening of the roadway along the working face is designed. Field measurements revealed that the above scheme can meet the stability requirements of the overlying roadway and the high efficiency and yield of the underlying working face. The results provide some references for the safe mining of coal in the 1000-m deep coal seam.

     

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