Investigation Into High Mining-induced Stress Evolution And Energy Distribution Field With Multi-seam Mining

In recent years, coal seams having good existing condition are lesser and lesser due to the large increase of mining intensity. Thus multi-seam mining has become an prevailing method to solve this problem. Bearing structure’s capacity decreases, large mining-induced stress forms, and mining stresses overlays each other due to multiple mining of coal seams. All these phenomena can lead to support difficulty, rock bursts, gas drainage difficulty, et al.According to the occurrence characteristics and mining technology of Coal Group A and B(No.B8, B7, B6, B5, B4,A3,A1 seam) in the No.4 mining area of Paner mine in Huainan Mining District, this paper researches the high stress evolution law and energy field distribution law under large scale mining of multiple coal seams through field measurements, numerical simulation, laboratory tests and theoretical analysis.Firstly, mining technology characteristics and mechanical parameters of coal (rock) are analyzed based on the large number of field tests. Then, The FLAC3D numerical model and 2D similar material simulation model are designed under the mining condition of multiple coal seams. The stress field of surrounding rock, evolution characteristics of plastic zone, and energy field distribution law are analyzed under one mining condition as well as multiple mining condition. Models of both the stress evolution and energy evolution are established under distressing mining condition based on the stress evolution. It shows that the stress of surrounding rock has a "overlay effect", and in the longitudinal direction has "homogenization effect" with the increase of distance away from the mining coal seam. Energy field and stress field show a similar distribution characteristic when extracting the coal. In front of the longwall face, it can be divided into three zones, include energy dissipation zone, energy activation sensitive zone, and energy storage stable zone.This research can provide an important reference for safe and efficient mining, especially for coal-gas extraction under the similar mining condition. It has significant social and economic benefits.