Ground pressure formation and control technique under high stress fragment rockmass

Supporting drifts in Xiaoguanzhuang Iron Mine destroy badly and the deformation of surrounding rock is no convergence deformation after the drifts are excavated. According to this condition, the drift excavation process of sublevel caving without sill pillars was simulated by rock failure process analysis and the stress variation of surrounding rock was analyzed to grasp the law of ground pressure activities in consideration of rock' s creep characteristic. Simulation results indicate that the destruction form of rib spalling, floor heave and roof falling occur when the drifts are excavated. High stress concentration in the ore-rock contact zone leads to severe destruction of pillars between two drifts; with the excavation of drifts, it diverts into surrounding pillars of the newly caved. Because of excavation sequence, high stress concentration occurs in the boundary ores, which leads to difficulty in mining of boundary ores. Bolt-mesh supporting is applied to control the deformation and destruction of drifts, which can ensure mining activities safely and successfully.