基于采动覆岩裂隙三维分布形态的地面L型抽采钻孔合理位置研究

Study on the proper position of gas drainage boreholes of L type based on the overlying fracture distribution in three dimensions induced by mining

高瓦斯矿井使用地面L型钻孔代替高抽巷抽采瓦斯,能够节省大量巷道掘进工程,减缓采掘接替紧张状况。为了研究L型钻孔的最优布置位置,以新景矿3213工作面为例,采用相似模拟和三维数值模拟,确定了采场上方覆岩的运移规律和裂隙带三维分布形态。根据采动三维裂隙分布形态建立三维裂隙场模型,导入COMSOL模拟软件,对不同位置的L型地面定向钻孔,模拟抽采过程中的瓦斯运移规律和富集分布区域。结果表明,抽采钻孔能有效降低采空区的瓦斯体积分数,钻孔布置在回风巷上方的"O"型裂隙区中上部时抽采效果最好。根据新景矿3213工作面实际情况,定向钻孔最优布置位置为垂直方向在回风巷上方距煤层顶板20~30 m,水平方向在回风巷内错平距15~30 m。经现场5个月的抽采试验,地面L型钻孔平均抽采瓦斯体积分数78.5%,抽采瓦斯纯量8.58 m^3/min,日抽采纯量达到11 953 m^3,占工作面总瓦斯涌出量的42.60%,有效地解决了工作面瓦斯的控制问题。

Gas drainage boreholes of L-type drilling from ground can save lots of roadway engineering and time compared with gas drainage roadway above the coal seam.In order to study the proper location of L-type boreholes,longwall panal 3213 in Xinjing coal mine was used as the in-site case.The overburden strata movement and fractures distribution in three dimensions induced by mining were obtained by discrete element software CDEM and physical similarity simulation test.The three-dimensional model of fracture field on the top of goaf was imported into software COMSOL.The gas migration law and gathering area around the goaf and its above area were obtained with different locations of L type drainage boreholes.The results showed that the gas concentration in the goaf could be effectively reduced by L type drainage boreholes.The proper position of the horizontal range of L type borehole was located on the middle-top range of fractured zone above the goaf.For longwall panal 3213,the proper position was 20~30 m above the coal seam in vertical direction and 15~30 m alternate of the tailgate in horizontal direction.The in-site drainage tests showed that the gas density was 78.5%,gas quantity was 8.58 m^3/min that was 119 53 m^3 for a day extracted by the L type boreholes.The drainage gas was 42.60% of the total gas emission quantity in longwall panel 3213,which was very significant for the gas control in this coal face.