Study on Gas Cubic Drainage Technology in Contiguous Seams
According to the mining in contiguous seams of Tongzi Mine,a seam with low gas content and low outburst danger was selected as a protective seam for coal mining.The mining disturbance role was applied to improve the permeability of the below pressure released seam.The borehole drilled along seam,low level strike borehole drilled through seam,pipeline buried in goaf,floor upward borehole drilled through seam and other measures were applied to comprehensive cubic gas drainage of the seam group.The experiment showed that the gas drainage rate of the coal mining face in protective seam was over 55%,coal and gas outburst danger was eliminated and the upper corner gas volume fraction was controlled below 1% after mining operation of the coal mining face completed.After the pressure released by the protective seam,the permeability coefficient of No.6,No.7 and No.9 seam was individually increased by 392,320 and 289 times,the gas drainage rate was over 60% and the safe and efficient coal and gas jointly mining realized.