South Toulon tube: 3D numerical back-analysis on in situ measurements

摘要

Full face excavation with ground reinforcement has become a common technique to build large tunnels in soft rock or hard soil. Nevertheless, at the design phase, it remains difficult to assess the effect of the different construction and reinforcement elements on the control of the ground movements and settlements. In order to improve the understanding of ground response to this tunnelling method, a monitoring section has been installed during the construction of the south Toulon tunnel (France). An important database was obtained and subsequently used for numerical back-analysis. A 3D FE calculation, modeling the real reinforcement system and construction stages, was then performed. The satisfactory matching between the numerical results and the in situ measurements shows that the three-dimensional numerical model with an explicit modeling of the reinforcement elements is a reliable tool to simulate the complex phenomenon of interaction between the excavation process, the reinforcements and the ground reaction.