Contact between a tunnel lining and a damage-susceptible viscoplastic medium

In this study, the contact and interaction between a tunnel lining sup- port and a damage-susceptible viscoplastic medium is investigated. First, back- analysis of the time-dependent behaviour of a drift excavated across a carbonifer- ous rock mass which exhibited large delayed displacements was undertaken. Drift closure was simulated using an elasto-viscoplastic constitutive model that included the strength degradation process. This 3D numerical simulation was performed taking into account both stage construction sequence and rate of excavation ad- vancement. A comparison of the numerical results with the data measured on site allowed for the calibration of the model parameters. Subsequently, the installation of a concrete lining was simulated to account for contact with the rock mass. This blind numerical simulation aimed to optimize the tunnel cross-section and estab- lish the dimensions of a suitable concrete supporting lining. Three months after installation, the stresses measured in the concrete lining were in agreement with the numerically predicted stresses.