Study on regional outburst prevention technology of multi directional 3Dgas pre-drainage in uncovering seam at cross-cut of mine

In order to solve a small borehole layout space of the gas drainage boreholes in the cross-cut, long borehole depth, hard to ensure the drilling in the position and borehole sealing difficulty under the special complicated geological condition in Southwest China area, a multi directional 3D gas pre-drainage and outburst control method was provided for the seam uncovering at the cross-cut of the mine. With the 3D and full covered borehole layout method and a full borehole casing applied to the borehole drilling, the “two sealing and one grouting” pressurized cement borehole sealing and gas drainage technology was applied to prevent a gas drainage blanking zone occurred in the seam uncovering area and to effectively reduce the seam gas content and the gas pressure at the front of the seam uncovering area. The engineering test result showed that with the application of the multi directional 3D gas pre-drainage and outburst elimination method, a 45 days continued gas drainage was conducted in the seam uncovering area, a total gas drainage volume was 329 776.46 m3, the gas pre-drainage rate was reached to 70% and the residual gas content and residual gas pressure were reduced to 5.800 8 m3/t and 0.25 MPa individually. In comparison with the gas drainage and gas pressure before the gas drainage conducted, the gas drainage and gas pressure ere reduced by 69% and 79% individually. The application of the technology could effectively control the coal and gas outburst disaster and ensure the safety of the seam uncovering at the crosscut.