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远距离下保护层开采卸压增透效应及瓦斯抽采方案

Pressure relief and permeability enhancement effect and gas extraction scheme of long-distance lower protective layer mining

  • 摘要: 针对深部远距离下保护层开采后上覆被保护层卸压及瓦斯治理难的问题,以朱仙庄煤矿Ⅲ1031工作面工程条件为背景,采用相似模拟和数值模拟相结合的方法,研究了远距离下保护层开采过程中覆岩的应力演化规律、变形破坏特征和卸压增透效果。结果表明:保护层开采,产生延伸至被保护层的纵贯式穿层裂隙,基本顶发生平均步距15 m左右的周期破断,煤层压力先减小,采空区中部重新压实后,应力开始逐渐恢复;在围岩内形成应力增高区域,而应力在向采空区中部演化时,则以近似于弧状的应力递减圈形态发育。因煤层采动在采空区两侧形成离层裂隙发育区,为瓦斯流动提供通道,被保护层也因此得到卸压,其卸压率达到0.91,增透率增幅为5%~20%,被保护层出现明显卸压增透效应。为解决保护层开采后瓦斯需卸压抽采的问题,设计了穿层钻孔、顺层钻孔、高位钻孔配合拦截钻孔和采空区埋管的瓦斯抽采方案。

     

    Abstract: In view of the difficulty of pressure relief and gas control of overlying protected layer after deep and long-distance lower protective layer mining, based on the engineering conditions of Ⅲ1031 working face in Zhuxianzhuang Coal Mine, the stress evolution law, deformation and failure characteristics and pressure relief and permeability enhancement effect of the overlying strata during long-distance lower protective layer mining were studied by means of similar simulation and numerical simulation.The results show that the protective layer mining produces a longitudinal penetrating fracture extending to the protected layer, and the main roof breaks periodically with an average step of about 15 m.The pressure of the coal seam decreases firstly, and the stress returns to the approximate original rock stress state after recompacting in the middle of the goaf.The stress-concentrated area is formed in the surrounding rock, and when the stress evolves to the middle of the goaf, it develops in an arc-like stress decreasing circle.Because of the coal seam mining, the separated layer fracture development area is formed on both sides of the goaf, which provides a channel for gas flow, and the protected layer is also relieved.The pressure relief rate reaches 0.91, and the antireflection increase rate is 5% to 20%.The protected layer has obvious effect of pressure relief and antireflection.In order to solve the problem of pressure relief and gas extraction protective layer mining, a gas extraction scheme was designed including cross-layer drilling, bedding drilling, high-level drilling with interception drilling and buried pipe in goaf.

     

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