Analysis of a bolt-reinforced tunnel face using a homogenized model
Résumé
This communication deals with the effect of tunnel face reinforcement on the wall convergence and on the loads in the lining, studied by means of a homogenized anisotropic model for reinforced ground. While the tunneling process is generally handled in a plane strain framework (within the so-called convergence-confinement method), tunnel face reinforcement makes it necessary to take into account the three-dimensional nature of the problem. In the case of an isotropic and uniform initial stress state, and of a circular tunnel, analyses can be performed in axisymmetric mode. Within this framework, finite element simulations have been carried out, using the finite element software CESAR-LCPC, to simulate the process of tunnel excavation and lining construction. Results indicate that reinforcement of the tunnel face reduces tunnel convergence and decreases the compressive forces in the lining. In the last place, it is shown that results obtained with the anisotropic multiphase approach can be approximated with an isotropic model with adjusted parameters, which may be useful for preliminary design.