Application of RFPA~(2D) Numerical Simulation for Parameters Optimization in Highly-located Boreholes
Based on importance of judging comprehensively coal nomal distribution range of the vertical three 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 714 working face of Qinan Coal Mine and combined with calculation results by empirical formula,coal nomal distribution range of the vertical three was analyzed preliminarily,that range of fractured zone is apart from above 71 coal seam roofs 18.4 ～ 49.0 m rock layer region was comprehensively judged and range of normal distance parameter of highly-located boreholes was chosen 18.0～34.0 m.The field application shows that methane concentration in boreholes is almost beyond 30.0 percentages,the max 53.2 percentages,while normal distance parameters of highly-located borehole controlled 20～35.0 m in construction.Then average quantity of drain gas of highly-located boreholes is 7.32 m3/min,the 60.6 percentages of which to total content of coal face gas emission,which is far greater than that by buried-pipe method in coal mine goaf,and average methane drainage rate of working face was improved to 60.0 percentages.