Experimental study of radial gas seepage characteristics in stress-relief boundary area.

Based on the coal samples of the outburst coal seam No. 8 of Qingdong Mine in Huaibei, with the distribution characteristics of ground stress and gas pressure in stress-relief boundary area, the experiment of outburst coal's radial gas seepage was carried out under variable axial pressure, gas pressure and hole diameter by a self-developed test system of radial gas seepage. The experimental results show that the gas seepage flow increases with the increase of gas pressure under fixed axial pressure, and the relationship between gas seepage velocity and gas pressure can be described as quadratic polynomial function, the permeability of coal samples decreases rapidly with the increase of gas pressure in the range of 0-0. 6 MPa, then decreases slowly with the developing of gas pressure and tends to be stable; the permeability of coal samples decreases linearly with the increase of axial pressure under fixed gas pressure; Affected by the borehole pressure relief, the permeability of soft and low strength coal samples with large diameter borehole is significantly higher than the coal samples with small diameter borehole in low axial pressure stage, both permeability gradually tends to be the same with the increase axial pressure. [ABSTRACT FROM AUTHOR]