The application of pneumatic directional drilling technology in gas pre-drainage of strips in soft coal seams

It is costly and inefficient to drill through floor tunnel to eliminate outburst in soft coal roadway strip in Huaibei Mining Area. The bedding pneumatic directional borehole technology can accurately control the borehole trajectory in the strip coal seam according to the design, and realize the outburst elimination of the strip coal roadway through drilling gas extraction. Based on soft coal seam characteristics of the Huaibei Mining Area, the coal lane stripes drainage of gas in the directional hole design, selection of pneumatic directional drilling equipment, directional bore blastholes and shield technology, the evaluation of extraction effect are studied. The technology has been successfully applied in working face Ⅲ635 for outburst elimination in Huaibei mining area. Seven boreholes were drilled, each of which was more than 300 m deep, and the screen was lowered throughout the whole process, creating the deepest record of 372 m bedding drilling in Huainan and Huaibei soft coal mining area. This successfully covers the excavation of coal roadway, reduces floor roadway and borehole through bed, and explores a new method for efficient gas control of coal roadway strip in soft coal mining area.