The optimization and application of large diameter borehole for pre-drainage of stripe gas in roadway

Aiming at the weak risk of outburst in seam Ⅱ₂in Mengjin Mine and the problem of slow advance rate in working face11031, the ranges of pressure relief and drainage effects of drill holes with different bore diameters were studied. Large diameter drilling was applied. The optimization of existing regional outburst elimination technology was carried out by the partition layout of drill holes. The outburst elimination effects were investigated in the area where measures were taken, it was found that a single hole drainage with 113 mm bore diameter was 1.8 times higher than that that of 94mm. The results indicated that the application of large diameter borehole in seam could eliminate gas outburst risk with pre-drainage of stripe gas effectively, enhance excavation speed and ensure the safe production in working face.