Study on optimization of strata passing borehole sealing depth and borehole layout space in floor gas drainage gateway

In order to study the gas drainage borehole spacing, borehole sealing depth and gas drainage time importantly affected to the gas drainage concentratio n, taking the high gas outburst seam group in Shaqu Mine as the object, based on the broken zone of the surrounding rock along the drilling site and the site of the stre ss concentrated zone, comparison experiments were conducted on the gas drainage with different borehole sealing depth, the COMSOL numerical software was applied to analyze the gas drainage time and the borehole layout spacing affected to the gas drainage effect and to provide the rational hole sealing depth and borehole layout spacing of the strata passing boreholes. The results showed that with the borehole sealing depth increased, the gas drainage concentration would be firstly steadily incr eased and then would be in stable and there was a critical sealing depth existed.With the gas drainage time extended, the gas pressure reduction between the neighbor ing boreholes would be in a superposition effect and would be in stable after the certain time of the gas drainage.The sealing depth and the borehole layout spacing of t he borehole passed through No.4 seam in Shaqu Mine were 10 m as determined.The average gas drainage flow from a single borehole measured would be in an attenu ation of the negative indexes with the time extended and the outburst danger of the gas drainage area would be effectively eliminated after one year gas drainage.