Study on Disaster Mechanism and Prevention of Air Leakage Channel in Shallow Close Distance Coal Seam Group

The shallow-buried close-distance coal seam group has the characteristics of large mining height, shallow burial depth and small interlayer spacing. After coal seam mining, a penetrating air leakage channel is formed on the surface and underground, which is the main cause of low oxygen in the return air corner. This paper, PFC simulation is used to study the caving law of overburden rock and the evolution process of air leakage channel during the mining process of working face. The results show that the low oxygen gas in the goaf of 12 # coal seam mainly migrates to the return corner of the lower 221014 working face. The main medium facilitating this is the interconnected inter-coal seam air leakage channel, and the primary driving force is the substantial and rapid decrease in surface gas pressure, leading to a significant gas pressure difference between the return airway corner and the goaf of the 12 # coal seam. Aiming at the low oxygen phenomenon in the return air corner. The governance measures involving even-pressure ventilation technology were proposed. Theoretical calculations determined a safe gas pressure adjustment range for the return airway corner to be between 88.328 and 88.549 Pa. The pressure equalizing ventilation technology effectively controls the pressure difference between the goaf of 12 # coal seam and 22104 working face, and reduces the air leakage. Finally, the oxygen concentration in the return air corner is increased to prevent excessive fresh air from pouring into the goaf.