Deep-tunnel section


The deep tunnel is 8.6 km long (included stations) and serves 9 stations (from Cleunay to Les Gayeulles).

The tunnel is excavated by a soft ground Tunnel Boring Machine (TBM), at a depth of 12 to 30 meters.
Precast concrete lining segments are laid one by one as the TBM progresses. Spoil are extracted by a belt conveyor which is extended as the excavation progresses.

KEY FEATURES :

- TBM length  : 92m
- TBM diameter : 9.44m
- TBM weight : 1,450t
- Excavation speed : about 200m per month
- Total of arch segments : 29,806
- Average excavation depth : -25m
- Maximum excavation depth : -34m
- Volume of excavated soil : 572,000m3
- TBM power : 5 mW
- Cutting wheel weight : 121t