Research on deformation characteristics of mining overburden rock on deep "three-sided" island working face

In order to study deformation and failure characteristics of mining overburden rock on the deep "three-sided" island working face with old goaf on the left, right and upper sides, taking 120502 working face of a coal mine as research object, the stress of overburden rock, displacement and deformation characteristics in plastic zone in the mining process were systematically and numerically studied using FLAC3D simulation software. The results show that in the stoping process, the "three-sided" island working face with the old goaf on the left, right and upper sides is mainly disturbed by the upper old goaf, and stress concentration of left coal pillar in the prone direction is higher, the vertical stress in front of working face on strike direction decreases first and then increases continuously, and the stress concentration factor increases continuously. The direction of vertical displacement changes from downward to upward, and the downward vertical displacement peak increases continuously, but the upward vertical displacement peak remains stable. The damage range of plastic zone appears "saddle shape", and gradually expands to be connected with the plastic zone of the adjacent three old goafs, and the rock mass above the roof is in the tension-compression stress zone, and the cracks in the surrounding rock of the goaf are more fully developed. The gas near the old goaf and the pressure-removing coal body flows to the goaf in the mining layer, so the gas drainage work in the goaf of the working face should be emphasized.