Study on the gas migration laws of non-pillar mining with gob-side entry retaining in high gas outburst coal seam

Abstract

Mining fractures are the channel of gas migration, and it is important to figure out the gas migration laws for gas control. Combined with the actual geological conditions of Shaqu No. 2 coal mine, a numerical model of no-pillar mining with automatically retained entry was built to simulate the deformation and fracture of overburden rock and the evolution laws of cracks above the goaf during mining. Subsequently, CFD software is used to theoretically stimulate the gas concentration distribution laws of non-pillar mining with the automatically retained entry in the stope under non-drainage and high-level borehole drainage conditions. The laws of gas concentration in the stope were compared and analyzed under the condition of the Y-type ventilation of non-pillar mining and U-type ventilation of coal pillar mining. The results show that Y-type ventilation of non-pillar mining reduces the gas concentration in the upper corner of the working face and the goaf, and effectively solves the gas accumulation problem in the upper corner of the working face in the mode of U-type ventilation of coal pillar mining. On this basis, the high-level borehole drainage technology is adopted to effectively reduce the gas concentration in the goaf. The research has certain guiding significance for the gas management of non-pillar mining with gob-side entry automatically retained.