迎采掘进巷道水力切顶关键部位对顶板断裂行为的影响

The influence of key parts of hydraulic roof cutting and roof fracture behavior in mining roadway

  • 摘要: 动压巷道往往存在着巷道变形严重、围岩控制困难等问题,动压巷道大变形问题通常与围岩自身特性和动静载叠加形成的应力环境有关。山西怀仁峙峰山煤矿5号煤层回采巷道掘进采用迎采动的掘进方式,即存在掘进工作面和回采工作面交锋的问题,迎采掘进会造成相邻工作面巷道的围岩结构失稳而引发大变形问题,使巷道维护困难,严重制约着煤炭资源的安全高效生产。针对此,提出了在应力传递路径上实施水力压裂的方法,破坏指定区域的岩体结构,从而降低巷道围岩范围内的应力,控制巷道的围岩稳定性;构建了坚硬岩层断裂部位的岩梁力学模型,通过峙峰山煤矿岩体的物理力学参数计算了水力切顶位置与顶板弯曲弹性能、顶板下沉速率的关系,分析了坚硬顶板断裂部位对断裂行为的影响。结合现场工程验证等方式,揭示了迎采掘进巷道大变形的机理,确定合理的压裂位置。研究结果表明:在坚硬岩层关键部位进行水力压裂切顶卸压可以破坏应力传递路径,降低上覆岩层的应力叠加效应,控制顶板能量释放的速率,压裂后巷道的累计围岩变形量普遍降低了40%~60%,表明在关键部位水力切顶实现了对迎采掘进巷道围岩的有效控制,有效解决了临近巷道的围岩失稳大变形的问题,理论结果可以指导现场施工,证实了模型的可靠性。

     

    Abstract: Dynamic pressure roadway often has problems such as serious deformation of roadway and di-fficult control of surrounding rock. The large deformation of dynamic pressure roadway is usually related to the characteristics of surrounding rock and the stress environment formed by the superposition of dy-namic and static loads. The mining roadway of No.5 coal seam in Huairen Zhifengshan Coal Mine in S-hanxi adopted the tunneling method of facing mining, there was a problem of confrontation between the tunneling working face and the mining working face. Large deformations caused by mining intersections that could result in destabilisation of the perimeter rock structure of the adjacent working face roadway, which made the roadway difficult to maintain and seriously restricted the safe and efficient production of coal resources. In view of this, a method of hydraulic fracturing on the stress transfer path was prop-osed to destroy the rock mass structure in the designated area, thereby reducing the stress in the surrou-nding rock of the roadway and controlling the stability of the surrounding rock of the roadway. The me-chanical model of rock beam at the fracture site of hard rock strata was constructed. The relationship b-etween the position of hydraulic roof cutting and the bending elastic energy of roof and the subsidence rate of roof was calculated by the physical and mechanical parameters of rock mass in Zhifengshan Coal Mine, and the influence of the fracture site of hard roof on the fracture behavior was analyzed. Combi-ned with field engineering verification, the mechanism of large deformation of mining and excavation ro-adway was revealed, and the reasonable fracturing position was determined. The results show that hydra-ulic fracturing and roof cutting pressure relief in the key parts of hard rock strata can destroy the stress transfer path, reduce the stress superposition effect of overlying strata, and control the rate of energy r-elease of roof. The cumulative deformation of surrounding rock of roadway after fracturing is generally reduced by 40%-60%, indicating that hydraulic roof cutting in the key parts realizes the effective cont-rol of surrounding rock of mining and excavation confrontation roadway, and effectively solves the probl-em of large deformation of surrounding rock instability near roadway. The theoretical results can guide the field construction and confirm the reliability of the model.

     

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