ABSTRACT
The present work aims at performing a numerical study of the response of the Fréjus road tunnel and of its safety gallery. This case study exhibits an interesting configuration of two parallel tunnels excavated in the same ground with different techniques: the Fréjus road tunnel was excavated by drill and blast methods in the seventies and its safety gallery was excavated with a single shield Tunneling Boring Machine (TBM) between 2009 and 2016.
Monitored convergences in the road tunnel are back-analyzed considering a visco-elasto-plastic constitutive behavior of the ground. This behavior is extrapolated to the neighboring zones of the safety gallery in order to predict the response in terms of stresses developed in the segmental lining. It is shown that the excavation method significantly affects the time-dependent parameters of the ground.
