Abstract: With the increase of metro operation mileage and service time as well as the influence of adjacent projects, the number of various hazards in the metro shielded tunneling excavation arealso more frequently encountered. In this paper, the deformation of a shielded tunnel excavation segment in different soil and rock strata under the crest loading and side unloading conditions is analyzed by the numerical simulations. The stress and deformation of shielded segment before and after the reinforcement with the internal steel plate are compared. The correspondent mitigation measures for the various hazards in the shielded segment are proposed. Both the analytical and construction monitoring results indicate that the application of internal steel plate for mitigating the defected shielded tunnel segment is successful.

Key words: Metro Subway, Hazard Mitigation, Numerical Analysis, Inside steel plate, Shield segment