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为了研究水力冲孔钻孔周围煤层透气性变化及分布规律,基于煤层实际赋存条件,采用压力法和含量法对水力冲孔卸压范围进行了现场试验考察。采用RFPA2D-Flow软件模拟分析了水力冲孔钻孔周围煤体应力及透气性变化规律。结果表明:受水力冲孔的影响,孔洞周围形成了半径为5.0~6.0 m的卸压范围,卸压范围内应力在0.038~6.545 MPa之间,在距被考察孔6.8 m处,出现应力集中现象,最大主应力为15.85 MPa,与现场考察结果基本一致。孔洞周围煤层透气性的分布规律与主应力变化趋势相一致。距卸压区域距离不同,煤体最大主应力不同,越靠近孔洞的区域,应力和瓦斯压力下降幅度越大,煤层透气性系数也就越大。
In order to study the variation and distribution of permeability of coal seam around hydraulic punching hole, based on the actual storage conditions of coal seam, the field test was conducted by using pressure method and content method. Using RFPA2D-Flow software simulation analysis of the hydraulic punching hole around the stress and permeability changes of coal. The results show that the pressure relief zone with the radius of 5.0-6.0 m is formed around the hole under the influence of hydraulic punching. The stress in the range of pressure relief is between 0.038-6.545 MPa. Stress concentration occurs at a distance of 6.8 m from the hole under investigation Phenomenon, the maximum principal stress is 15.85 MPa, basically consistent with the field investigation results. The distribution of permeability of coal seam around the hole is consistent with the trend of the principal stress. Different from the pressure relief area, the maximum principal stress of coal is different. The closer the area is to the hole, the bigger the decrease of stress and gas pressure, the bigger the permeability coefficient of coal seam.