Abstract: Based on the present situation that pre-drainage couldn’t eliminate outburst effectively in low permeability coal seam of Jiulishan Mine, hydraulic flushing technology was selected to enhance permeability in cross-seam holes, and the drainage effect was also investigated. The study showed that the hydraulic flushing implemented in 16051 floor tunnel was effective to eliminate the outburst potential energy and enhance the permeability around the drill. After rushing 1~2t coal, the equivalent borehole diameter of the drainage borehole was improved by 2.0~2.6 times, the average pre-drained gas flow of the borehole would be over 5 times than before the hydraulic flushing conducted, the attenuation coefficient of the gas flow reduced from 0.0733d-1 to 0.039d-1, pre-drainage showed a better drainage effect, and made it available to excavate roadway safety and quickly.

Key words: single coal seam, hydraulic flushing, cross-seam hole, flow