Analysis of the Interaction between the Lining of a TBM Tunnel and the Ground Using the Convergence-Confinement Method

The support used when a tunnel is excavated by a shielded TBM is complex because it consists of two different materials: A concrete segmental lining and a filler annulus between the lining and the tunnel wall. A detailed analysis of the behavior of such a support system requires a three-dimensional numerical modeling and should also consider the presence of the TBM machine. This article presents an analytical calculation procedure that allows to assess the interaction between the support system and the tunnel using the convergence-confinement method and Vlachopoulos-Diederichs method. Furthermore, it is defined the overall stiffness of the support system starting from the detailed analysis of the stresses and strains developed in the two constituent materials. From the analysis of the evolution of the radial displacements in the longitudinal section, it was then possible to evaluate another fundamental parameter: The radial displacement of the tunnel wall at the point of installation of the support system. The computational procedure was then applied to a specific case, showing the influence of the stiffness of the filling material on the final loads acting on the segmental lining.