Evolution of unloading damage and distribution of fractures in gas channel under repeated mining
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Zhang Bichuan, Zhou Houquan, Liu Yanbao, Xiong Wei, Ba Quanbin, Shen Kai
In order to solve the problem of over-limit gas in the corner of the mining stope, the influence of repeated mining on the unloading of the roof and the deepening of the mining fissure is analyzed based on the unloading rock mechanics. The damage factor and the infiltration are established by combining the damage mechanics. The relationship between the rate and the discrete element software is used to calculate the damage evolution law of the unloading gas channel before and after repeated mining. The influence range of the mining fracture field is obtained according to the relationship between effective stress and permeability. The results show that the unloading degree of the roof in the goaf increases nonlinearly with repeated mining. The greater the unloading amount and the damage factor of the roof in the goaf after repeated mining, the more the number of mining fissures develops, and the permeability of the goaf. The height of the mutation point and the development of the gas channel is greater.
Mining fissure, Repeated mining, Gas drainage, Roof, Gas migration