Analysis on gas drainage effect of large diameter roof directional long borehole instead of high drainage rock roadway

In order to further improve gas drainage effect in the fracture zone of the gob to ensure the safety of the working face during mining, a large diameter roof directional long borehole(ø203 mm)was proposed for gas directional drainage in the fracture zone of mining area, and its construction technology, reasonable layout of drilling holes and drainage effect were studied.The results show that the reasonable vertical height of the borehole layout is 45～50 m, and the horizontal distance between the borehole and the return air lane of the mining face is 40 m.Compared with gas control methods in conventional mining areas such as high-drainage roadways and high-level boreholes, the extraction volume of large-diameter directional long bores on roof is equivalent to that of high-level extraction roadways, and it is 2.04 times of that of common roof high-level borehole; the engineering volume is greatly reduced.Large-diameter roof-oriented long drilling can not only achieve high-efficiency extraction, but also save engineering volume and reduce construction costs.The successful application of of this technology provides a practical basis and development direction for the improvement of the technology of replacing roadway with hole and the traditional high position hole in roof.