RFPA~(2D)数值模拟在高位钻孔参数优化中的应用

基于准确划分煤层上覆岩层"竖三带"的煤层法向分布范围,以及有效提高高位钻孔瓦斯抽采效果的重要性,应用RFPA2D软件数值模拟祁南煤矿714工作面顶板垮落情况,初步分析了"竖三带"的煤层法向分布范围,并结合经验公式的计算结果,综合判定距71煤层顶板上方18.4～49.0m的岩层区域为裂隙带,高位钻孔法距参数的取值范围优化选择为18.0～34.0m。现场应用表明,高位钻孔的法距参数施工控制在20.0～35.0m时,钻孔抽采瓦斯体积分数均在30%以上,最大为53.2%。同时,高位钻孔的平均瓦斯抽采量为7.32m3/min,占工作面总瓦斯涌出量的60.6%,远高于采空区埋管技术的瓦斯抽采量,并且工作面的平均瓦斯抽采率提高到60.0%。

Application of RFPA2D Numerical Simulation for Parameters Optimization in Highly-located Boreholes

Based on the importance of judging comprehensively coal nomal distribution range of "the vertical three zone" in overlying strata above coal seam and improving gas drainage effect of highly-located borehole effectively,with RFPA2D numerical simulation software to simulate gob roof caving in the 714 working face of Qinan Coal Mine and combined with calculation results by empirical formula,coal nomal distribution range of "the vertical three zone" was analyzed preliminarily,that the range of fractured zone is apart from above 71 coal seam roofs the 18.4 ～ 49.0 m rock layer region was comprehensively judged and the range of the normal distance parameter of highly-located boreholes was chosen 18.0～34.0 m.The field application shows that the methane concentration in boreholes is almost beyond 30.0 percentages,the max 53.2 percentages,while the normal distance parameters of highly-located borehole controlled 20～35.0 m in the construction.Then the average quantity of drain gas of highly-located boreholes is 7.32 m3/min,the 60.6 percentages of which to the total content of coal face gas emission,which is far greater than that by buried-pipe method in the coal mine goaf,and the average methane drainage rate of the working face was improved to 60.0 percentages.