近距离下邻近煤层群开采采空区瓦斯治理技术

Technology for controlling gas in goaf of contiguous lower adjacent coal seam group

为解决下邻近煤层群卸压瓦斯造成工作面上隅角超限严重以及支架间和采空区底部瓦斯不能及时被抽离等问题,基于近距离下邻近高瓦斯煤层群采动卸压瓦斯涌出规律,提出内错式迎向斜切钻孔辅助顶板高抽巷抽采采空区瓦斯技术。利用顶板垮落与钻孔形态演变规律,实现钻孔依次辅抽上隅角、支架间和采空区底部等富集区瓦斯,并在高家庄煤矿2号煤层2203回采工作面试验考察。结果表明:与高抽巷单一抽采效果相比,内错式迎向斜切钻孔辅助抽采条件下的叠加抽采平均瓦斯体积分数达15. 1%、提升1. 3倍,平均抽采纯量达18. 61 m3/min、提升1. 9倍,叠加抽采率达50%,抽采量占邻近层和采空区瓦斯涌出总量的83%,回风流和上隅角瓦斯体积分数控制在0. 6%以下,可有效保障工作面的顺利回采。

The gas( methane) concentration in the upper-corner of coal mining face was always higher extremely than the limit after releasing the pressure of the lower coal seams group,and the gas in the bottom of goaf and among the supports also could not be drainaged in time. To address these problems,a new auxiliary technology of the roof drainage tunnel for gas drainage in goaf was developed.The technology is characterized by inner interlocked oblique drilling. According to the evolution law of roof collapse and drill hole form,the gas was drainaged from the upper-corner,among the supports and the bottom of goaf.The drainage effect of the technology was investigated in the coal mining face of 2203 in Gaojiazhuang mine. The test results show that the average volume fraction of gas is 15. 1%,which increases by 1. 3 times as compared with the single drainage technology of the roof drainage tunnel,that the average net gas amount is 18. 61 m3/min,which increases by 1. 9 times,that the superposition gas drainage efficiency is50%,and the drainage volume accounts for 83% of the total gas emission from adjacent layers and the goaf,and that by using the technology,the volume fraction of gas in the air return way and upper-corner of coal mining face is limited to 0. 6% or lower,and the smooth mining of working face is effectively guaranteed.