Abstract: In this paper, the action mechanism of methane gas in the process of coal blasting damage and fracture were analyzed comprehensively based on the experiment, numerical simulation, and theoretical analysis results. The process of coal blasting damage and fracture includes the initial stage acted by blasting wave and the later stage acted by detonation gas and methane gas. The methane gas has positive role in the whole process, which can increase the blasting damage degree and the crack propagation velocity. In the initial stage, the methane gas can increase the stress wave peak, extend the action time and reduce the decay rate of stress in the tensile phrase. In the later stage, the methane gas takes pate in the crack propagation process drived by detonation gas, and the crack propagation will further promote under the superposition action of methane gas pressure field and detonation gas quasi-static stress field.

Key words: methane gas, coal blasting, damage and fracture, action mechanism