Reliability Analysis For Face Stability Of Slurry Shield Tunnel

Face stability of slurry shield tunnel is of great significance for the safety of the tunnel construction and normal operation.By taking slurry shield tunnel as a research object, the process of tunnel excavation is simulated by ANSYS software and reliability index for face stability of slurry shield tunnel under different slurry pressure is analyzed, which is based on the numerical simulation method and structure reliability theory. The study includes as follows:1. The forms, the affecting factors and the failure criterion of unstable face of tunnel are summarized. Drucker-Prager criterion is chosen as the failure criterion which is used to judge the face stability of slurry shield tunnel.2. The process of calculation for excavation face stability by ANSYS software is expanded. Three-dimensional nonlinear finite element analysis is carried out on the tunnel excavation face and the limit support pressure at excavation face is calculated.3. The influences of random depth of tunnel, cohesion and angle of internal friction on the limit support pressure at excavation face are analyzed.4. Based on the data of stratum parameter and the limit support pressure under different working condition, probability distributions characteristics are analyzed. Principle of designed slurry pressure of shield tunneling is discussed and the limit state function of excavation face stability is established. Reliability index of revised slurry pressure during the construction is calculated and the reasonable revised support pressure is advanced.Base on the reliability theory, the reasonable slurry pressure of shield tunneling is determined and it can be used to control the slurry pressure so as to ensure the stability of excavation face, which is an innovation in this thesis.