Studying the Favorable Zone for Pressure-Relief Gas Extraction by Combining Numerical Investigation and On-Site Application

Gas extraction in the pressure-relief area using depressurization effect of seam mining is an effective way to solve coal-mine gas problems. In this paper, we performed numerical modelling 204 working face via FLAC 3D, by which stress variation rock mass and associated permeability evolution during advancement were investigated. Furthermore, favorable zone for pressure relief was proposed based on performance on-site boreholes. The results show that: (1) varies with three zones overlying variation, becomes stable when height remains unchanged; (2) ranges from 13 m 19 Dv, boreholes are located, presents better than other areas; (3) volume optimized scheme rises 77.46 m3/min a 77.26% rate, eliminating overrun upper corner increasing speed 6.4 m/d. verification confirms simulation scope, more accurately determining extraction. This may provide reliable approach improving reducing engineering costs.