抽象的な

Research on drawering and excavating gases with the big direction perforate in coal mine

Chen Gui

By describing the design and construction of directional drilling underground, and the effect of the gas extraction, the paper indicating that the process is stable and with low cost and it’s convenient to control, by which the gas will be extracted after been relieved by the protective layer. Compared with the other processes being used on the ground, the advantages are more prominent, the process is valuable in promotion