Study on air leakage and gas distribution in goaf of Y-type ventilation system

Abstract

ABSTRACT In order to reveal the law of air leakage and gas distribution in goaf of fully mechanized mining face under Y-type ventilation, the numerical simulation of gas distribution in goaf was carried out with Comsol Multiphysics multi-physical field numerical simulation software under the field background of 31009 working face of Yangquan Xinyuan Coal Mine. Through the simulation results, we can see that the Y ventilation mode affects the gas depth 2–3 m more than the U ventilation mode, and the Y ventilation mode uses the airflow of the auxiliary air inlet to disperse the gas accumulation in the goaf and the upper corner. The results show that the air leakage from the 31009 working face to the goaf is 481.92 m3/min; the high air leakage area of the 31009 working face is 46.5 m in front of the working face, and the depth of gas distribution affected by airflow is 59 m; the low air leakage area is 46.5–232.5 m. The results show that compared with U-type ventilation, Y-type ventilation can reduce gas concentration in the working face and upper corner. The three-dimensional spatial distribution law of gas in goaf is similar to the “O” circle theory of mining fissures. Along the strike direction, the gas concentration in the deep goaf increases gradually; in the incline direction, the gas concentration in the middle of the goaf is higher than that on both sides of the goaf; in the vertical direction, the gas concentration increases gradually. The air leakage flow field affects the gas concentration distribution in the goaf. In the position with larger air leakage, the gas concentration is lower and the influence range is larger. The results of field measurement and numerical simulation are consistent, which provides a scientific basis for the problem of gas exceeding the limit in Y-type ventilation control face and upper corner.