Numerical simulation study on “three zones” of spontaneous combustion in goaf by “110 construction method” under different ventilation modes

In order to explore the distribution characteristics of “three zones” of spontaneous combustion in goaf under different ventilation modes, based on the engineering background of “two into one” ventilation mode at 1532 (1) working face of Gubei Mine, and based on airflow control equation, concentration component equation and energy equation, by using the Fluent numerical simulation method, the multi-physical coupling numerical model of coal spontaneous combustion and the real-time dynamic advance model of working face are established, and the distribution characteristics of “three zones” of spontaneous combustion in goaf by the “110 construction method” under three ventilation modes are simulated. The results show that with the continuous advance of the working face, under the conditions of ventilation mode 1 (air intake from the machine side and gob-side entry retaining, return air along the return air lane) and ventilation mode 2 (air intake from the machine side and along the return lane, and return air in gob-side entry retaining), the oxidation spontaneous combustion belt in the goaf is evenly distributed in the side of the belt machine, the middle of the working face and the side of the lane, and the oxygen concentration distribution is not much different. About 50 days after mining, the highest temperature appeared in the deep side of the transportation lane, and the temperature at this position did not increase with the continuous advance of the working face. Under the condition of ventilation mode 3 (air intake in gob-side entry retaining and return air lane, and air return at the side of the machine lane), the oxidation spontaneous combustion belt at the side of the goaf retaining roadway becomes 2-4 times wider, the middle of the working face and the side of the belt conveyor become obviously narrow, the oxygen volume fraction at the side of the belt conveyor in the goaf is lower, the oxygen concentration at the side of the belt conveyor is higher, and the air leakage increases significantly. The high temperature location of goaf mainly appears in the side of the stop line of 1532(1) working face, and the temperature of goaf here is the highest after 50 days of working face. In summary, combined with the actual situation of the site, the width and location of the oxidation spontaneous combustion belt are analyzed, and the ventilation mode 3 is finally determined to be more conducive to preventing the occurrence of coal spontaneous combustion, which provides theoretical guidance for the prevention of coal spontaneous combustion in mines.