Construction technology and development tendency of high level directional driling in seam roof

Based on a theory on a vertical"three zones' 'and lateralthree blocks"of goaf roof, the paper analyzed the basic principle and advantages of the gas drain age with the high level directional long borehole drilling technology of the seam roof, summarized and included the technical features of the " directional pilot borehole + reaming" construction technology and introduced the composition of the construction equipment system.The boring technology and equipment were applied to conduct a site trial on No.4101 coal mining face in Wenjiapo Mine of Shaanxi Bingchang Group.Two high level directional drillings were completed in the roof with a total drilling mater of 1 221 m and a single main borehole depth over 480 m.Meanwhile, according to the problems existed in the available construction technology of the high level directional drilling in the roof, the paper provided and introduced a hydraulic and percussive secondary rock breaking and remaining drilling technology and large diame ter directional drilling technology in order to further increase the final borehole diameter of the drilling, to improve the drilling construction efficiency and to ensure the C onstruction safety of the drilling.