Study on the Long-Distance Gas Pre-Drainage Technology in the Heading Face by Directional Long Borehole

Gas control in the heading face of a coal roadway is an important and difficult point mining China. On basis analyzing disadvantages high gas cost long drainage period existing mine face, long-distance pre-drainage method drilling proposed to so as improve tunneling speed. Applied engineering geological conditions Changcun mine, technology studied detail. First, migration model considering permeability changing with time established, put into numerical simulation software study variation law pressure under single borehole multi-borehole drainage. The results show that increase time, around increases gradually, decreases at boundary most, reaching 1.2 times initial permeability. In process drainage, there will be mutual influence between boreholes, but spacing, degree this gradually decreases. Second, according simulation, reasonable scheme designed applied field. field application shows has good effect, concentration flow are level for cuttings quantity always lower than critical value, excavation length by more 50 m per month. These indicate promising realize safe rapid roadway.