软岩保护层开采覆岩采动裂隙带演化及卸压瓦斯抽采研究

Evolution of overburden mining-induced fractured zone and pressure-relief gas drainage in soft rock protective seam

针对软岩保护层开采后上覆被保护煤层卸压瓦斯治理问题,以淮北芦岭煤矿首例软岩保护层开采试验为工程背景,采用综合研究方法研究软岩保护层开采覆岩采动裂隙带演化特征。结果表明:Ⅲ11软岩保护层开采后覆岩冒落带和裂隙带最大发育高度分别为10.1~12.4,52.7~59.95 m,采空区侧及上覆被保护层煤层下部存在竖向裂隙发育区和远程离层裂隙发育区;设计地面采动井和拦截钻孔抽采覆岩8、9煤层卸压瓦斯,优化地面采动井终孔位置垂直方向距顶板法距20 m,倾斜方向距风巷或机巷平距35 m,拦截钻孔终孔位置距9煤底板5 m。考察期卸压瓦斯抽采实践表明,软岩保护层开采后覆岩"两带"发育高度的判断和卸压瓦斯富集区域的辨识是合理正确的。

In view of the problem of pressure-relief gas drainage of overlying protected coal seam after mining the soft rock protective seam,with the first soft rock protective seam mining test in Luling coal mine in Huaibei city as the engineering background,the study of the overburden mining-induced fracture zone evolution characteristics in the test has been carried out through comprehensive research methods.The results have shown that the maximum development height of the fall zone and the fracture zone are 10.1〜12.4 m and 52.7〜59.95 m respectively after the mining of the soft rock working face.Meanwhile,there are vertical fissure development zones and remote separation fissure development zones in goaf side of the soft rock working face and the lower part of the protected coal seam.Furthermore,ground mining wells and intercepting boreholes have been designed to take out pressure-relief gas covering No.8 and No.9 coal seams.The bottom position of borehole has been optimized in ground mining wells 20 m away from the normal distance of roof in the vertical direction,35 m away from the horizontal distance of the air roadway or machine roadway in inclined direction,and that of the intercepting hole 5 m away from the floor of No.9 coal.During the inspection period,the pressure-relief gas drainage practice has shown that after mining the soft rock protective seam,both the judgment of the development height of overburden 44two belts,9 and the identification of the gas-enriched area of pressure-relief gas are correct and reasonable.