Numerical analysis on the influence of gas extraction on air leakage in the gob

• The simulation results of air leakage in a coal mine are validated by field data.
• Relations between volumes of air leakage and the gas extraction are obtained.
• Critical value of the gas extraction volume for air leakage control is achieved.

Air leakage volume from the working face to the gob is affected by gas extraction. This paper focuses on the numerical study of the flow field at the working face in a coal mine. Results show that the distribution of air volume at the working face, the pressure difference between the upper and lower corners, and the negative pressure of gas extraction from high drainage roadway obtained by the simulation are in good agreements with the actual field data. Furthermore, the influences of gas extraction on air leakage in the gob were studied. The results show that the gas extraction of high drainage roadway has negative effects on controlling the air leakage into the gob. The gas extraction not only affects the air leakage volume, but also affects the range of air leakage. The relations between the gas extraction volume and the air leakage volume were also studied. Results show that the air leakage volume in the gob and the air volume at working face have a third-order polynomial relation, while the air leakage volume in the gob and the gas extraction volume have an exponential relation, and the critical gas extraction volume was obtained through the relations. The result of the simulation provides useful information for the mining safety of coal mines.