Stability analysis and controlling technique for surrounding rock of grouting chamber with large cross section

For the purpose to solving the difficulties in controlling the stability of surrounding rock of the large cross section chamber, FLAC^3D software is used to simulate the failure characteristics of the surrounding rock for the chamber.Results of the simulation indicate that key positions for controlling the surrounding rock deformation are the corners in roof and floor of the chamber and the middle in the chamber wall.The principle of the excavation includes using ore pass to putting down the gangue, excavation from top to bottom in slice, and immediate supporting technical, which aims to reduce the failure caused by excavation disturbance.Combined support scheme of “anchor bolt+anchor cable+steel mesh+sprayed concrete” is proposed to support the roof and wall of the chamber.The first-time shotcrete sealing the surrounding rock timely, while the subsequent supporting technique of “anchor bolt+anchor cable+steel mesh+sprayed concrete” could improve the bearing capacity of the surrounding rock.Reinforced concrete and anchor cable is used in the bottom supporting of the chamber in order to avoiding shear failure in the corner in the floor.Monitoring results indicate the supporting structure greatly meet the long-term requirements of stability and seepage-proofing for surrounding rock of the chamber.