近距离特厚夹矸煤层多向消突技术研究

Research on Multi-Directional Gas Outburst Elimination Technology of Close-Distance Coal Seam with Extra-Thick Parting

为解决底抽巷条带瓦斯抽采消突技术存在的工程造价高、施工周期长和消突效率低等问题,以山西上良煤矿3-2、3-3近距离特厚夹矸煤层为工程背景,提出利用矸石层开掘钻场,施工顺层定向长钻孔多向预抽煤层条带瓦斯实现区域消突。通过建立煤层条带瓦斯多向渗流模型,引入最不利抽采理论,对煤层瓦斯压力变化进行无差别数值模拟,同时结合现场数据,对两种技术的消突效果进行双向对比分析。结果表明:顺层定向长钻孔多向消突方式下,煤层瓦斯由于顶底板限制作用,在水平方向运移倾向性更强,瓦斯压力降低等值线呈椭圆形分布;底抽巷方式下,瓦斯压力降低等值线呈环形分布。提出的顺层定向长钻孔多向消突技术使3-2煤层、3-3煤层瓦斯压力分别在抽采70d和110d后达到消突要求,消突效率较底抽巷抽采消突方式提升55%~143%,日抽采瓦斯纯流量、浓度分别提升35%和14%,同时施工成本节约65%,工期缩短56%,可以为近距离特厚夹矸煤层的瓦斯高效治理提供参考。

In order to solve the problems of high engineering cost,long construction period and low efficiency of outburst elimination for strip gas extraction and outburst elimination of the bottom drainage roadway technology,3-2and 3-3closedistance coal seams with extra-thick parting in Shanxi Shangliang Coal Mine were taken as the engineering background.Using the parting?X to excavate the drilling field was proposed and the directional long boreholes were constructed to pre-extract strip gas from coal seam to achieve regional outburst elimination.By establishing the multi-directional seepage model of strip gas in coal seam and introducing the most unfavorable extraction theory,the indifference numerical simulation of coal seam gas pressure change was carried out.At the same time,combined with the field data,the two-way comparative analysis on the outburst elimination effects of the two technologies was carried out.The results show that,under the layered directional long borehole multi-directional gas outburst elimination method,the coal seam gas has a stronger tendency to transport in horizontal direction due to the restriction of the roof and floor and theРИ젷렀볏gas pressure reduction contours are elliptically distributed;while under the bottom drainage roadway method,the gas pressure reduction contours are circularly distributed.The proposed layered directional long borehole multi-directional gas outburst elimination technology can enable the gas pressure in 3-2coal seam and 3-3coal seam to reach the elimination requirement after 70dand 110dof extraction respectively,and the elimination efficiency is 55%-143%higher than that of bottom drainage roadway technology,and the daily drainage flow and concentration of extracted gas are 35%and 14%higher respectively,meanwhile,the construction cost is saved by 65%and the construction period is shortened by 56%.The study can provide a reference for the efficient management of gas in close-distance coal seam with extra-thick parting.