Instability mechanism and bracing optimization for roadway groups with soft and fractured surrounding rock in Pan'er Coal Mine

Based on the roadway groups in the shaft station of the second east mining area, Pan'er Coal Mine, the characteristics of deformation and fracture of surrounding rock and bracing structure as well as their instability mechanism are analyzed by means of the engineering geological investigation, laboratory experiment, numerical simulation and theoretical analysis. An integrated multiple-step control measure and the design method for the roadway groups with soft and fractured surrounding rock are put forward, which mainly include pretension bolt and cable-steel support-grouting to control the roof and sidewalls, and at the same time side/floor corner bolt-pretension cable in the floor to control the floor. The research achievements are applied, and the in-situ monitoring results show the proposed method and the control strategy are scientific, rational and effective.