Abstract：Abstract The failure background of an isolated rock wall in soft fractured rock mass of a mine shaft bottom is introduced. The in-situ rock stress near the shaft bottom is measured by using the over coring technique of hollow inclusion gauge. Four core boreholes are drilled from the surface of shaft field，and two core boreholes are drilled from the underground opening，which go into the isolated rock wall. Many core rock samples are obtained from the boreholes. The clay minerals of the rock samples are analyzed qualitatively and quantitatively，and the physico-mechanical parameters of the samples are tested. Using Hoek-Brown rock mass strength criterion，the strength parameters of the isolated rock wall are determined. The deformation parameters and Poisson’s ratio of the rock mass are also determined by W. Dershowits’ experience method. By using engineering geological classification-supporting method for surrounding rock stability of underground tunnel，the suitable support pattern and system are determined. The stability of the surrounding rocks and support system of the tunnels in the mine shaft bottom is analyzed according to the calculated and simulated results of 3D FEM. The reason of unsuccessful support in the past is analyzed，and a new type of reinforcement support for the isolated rock wall is proposed，which uses prestressed cable and grouting and makes successful application to practice.
