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煤层瓦斯抽采是避免煤矿瓦斯灾害发生的根本防治措施,水力割缝技术使煤体在割缝后应力松弛、卸压、破坏、破裂,以成倍或者十几倍地提高煤层的渗透性,继而对煤层瓦斯进行抽采,使瓦斯煤层变为低瓦斯或无瓦斯煤层,从根本上避免瓦斯灾害发生。从水力割缝技术切割煤层致煤层应力变化角度,将理论分析和数值模拟方法相结合,根据渗流力学平面径向流理论,分析给出水力割缝技术增透抽采瓦斯原理。以兖州东滩矿3号煤层为例,分析采用水力割缝技术前后煤层应力变化、渗透率变化规律。结果表明:大面积割缝后,应力重新分布,由均匀状态转变为非均匀状态分布,水平缝使煤层卸压,煤层应力普遍降低,在缝上部煤层局部形成拉应力区。割缝后渗透率是割缝前的4.34倍,渗透率大幅度增加,从而提高瓦斯抽采速度和最终抽采率。
Coal seam gas drainage is to prevent the occurrence of coal mine gas disaster prevention and control measures, hydraulic kerf technology to make the coal slack in the stress relaxation, pressure relief, destruction, rupture, to multiple or ten times to improve the permeability of the coal seam, In turn, the coal seam gas drainage, gas coal seam into low-gas or non-gas coal seam, fundamentally avoid gas disasters. According to the radial flow theory of seepage mechanics plane, the principle of seepage improvement by hydraulic kerf technology is given by combining the theoretical analysis and numerical simulation method. Taking No.3 coal seam of Dongtan Mine in Yanzhou as an example, the variation of stress and permeability of coal seam before and after hydraulic cutting technology is analyzed. The results show that the stress redistribution changes from homogeneous state to non-uniform state after large area kerf. The horizontal seam relieves the pressure of coal seam and generally reduces the stress of the coal seam. The tensile stress zone is locally formed in the upper seam seam. After cutting seam permeability is 4.34 times before cutting, permeability increased significantly, thereby increasing gas extraction rate and the final extraction rate.