Application of Strength Reduction Method to Stability Analysis of Shield Tunnel Face

To appraise and supervise the rationality of face stability in the design and construction of shield tunnels,strength reduction method has been applied to the analysis of stability of shield tunnel faces.Safety factor of the shield tunnel face has been defined so that the stability safety factor of the tunnel face and the corresponding slip face of the tunnel are obtained.The effect of soil parameters,support pressure and ground water level on the safety factor of the face stability has also been analyzed.The analysis shows that the material parameters of soil and rock such as elastic modulus,the Poisson’s ratio have little effect on the safety factor yet the friction angles of soil,cohesive forces,support pressures of tunnel faces and the levels of underground water have much effect on the safety factor.