3D Modelling for Mechanized Tunnelling in Soft Ground-Influence of the Constitutive Model

The main purpose of this study was to provide a three-dimensional numerical model which would allow to show the influence of the constitutive model of the ground on the tunnel lining behaviour and displacement field surrounding the tunnel. Most of the processes that occur during mechanized excavation have been simulated in this model. Besides the well-known elastic linear perfectly plastic model with Mohr Coulomb failure criteria (MC), the Cap-Yield model (CYsoil), which is a strain hardening constitutive model that takes into consideration the hyperbolic behaviour of the soil has also been adopted. The results have shown a considerable effect of the constitutive model on the tunnel behavior and the ground displacement field. Generally, the CYsoil model produces higher structural force and ground settlement values than those predicted by the MC model.