ABSTRACT
Fréjus tunnel and its safety gallery between France and Italy in the Alps exhibit an interesting configuration of two parallel tunnels excavated in squeezing ground. They have a similar size and have been executed with different techniques. The road tunnel was excavated with traditional methods in the seventies and its safety gallery was excavated between 2009 and 2016 with a single-shielded TBM. The analysis of monitoring data collected from the road tunnel over a period of a few months before the installation of the final lining provides an accurate evaluation of the time-dependent response of the rock mass.
The present work presents a comprehensive study of the convergence measurements retrieved from Fréjus road tunnel and from its safety gallery and proposes the identification of zones with a similar response for both tunnels.
The focus of the paper is on the calibration of a visco-plastic anisotropic constitutive model based on the convergence measurements of Fréjus road tunnel. The information obtained from the study of the road tunnel can be extrapolated to the zones of the gallery showing a similar behavior. This allows carrying out a back-analysis of the safety gallery response using the proposed model.
