Analysis of spatial and temporal effects of three-dimensional gas drainage from coal seams in working faces
In view of the difficulty of gas drainage in low-permeability coal seam,taking the mining area coal seam of No.220112 work-ing face of of Xinji Second Coal Mine as background,a three-dimensional gas drainage system combining inclined bedding drilling,floor through layer drilling,roof directional drilling and upper corner buried pipe drainage was adopted to extract gas.The data of gas drainage show that the gas drainage of mining coal seam has a certain spatial effect and space effect,and the mixture amount of gas drainage and concentration of gas decrease and tend to be stable with the increase of drainage time and distance.The concentration and mixing a-mount of gas drainage by buried pipes and high drainage roadways in the upper corner have good consistency with the cyclic pressure of the roof.The gas drainage by buried pipes in the upper corner is greatly affected by cyclic pressure.Before cyclic pressure,it is necessa-ry to strengthen the gas drainage in the upper corner to prevent the gas from exceeding the limit during cyclic pressure.The drainage re-sults showed that the gas pre-drainage rate in the mining area of working face was 31.9％,the measured maximum residual gas content was 3.5 m3/t,the maximum residual gas pressure was 0.25 MPa,the maximum value of gas desorption index of drilling cuttings was 90 Pa,the maximum value of drilling cuttings was 2.6 kg/m,and a good drainage effect was achieved,the safety mining of the mining face was realized.
low permeabilityspatial and temporal effectgas concentrationdrainage effectthree-dimensional drainage
万方数据
维普
