Seen at NFM Technologies‘ Le Creusot works in central France, the world’s largest TBM (without cutterhead for now), being assembled and tested for shipment in March by sea from the south of France and by canal through the Netherlands. (See News Sep 2000)
The 14.7m excavation diameter, 12.2m long monster is destined for work with a joint venture of leading contractors Bouyges and local company Koop Holding Europe on the 7.2km long twin-track Groene Hart tunnel, part of the HSL Zuid high-speed train project in the Netherlands, where it is scheduled to be assembled in June and to be operational in September. Also being assembled at Le Creusot ia a 120m long, 2-part back-up system.
The option of a twin-track single bore was chosen by HSL Zuid and the dutch transport ministry in preference to two tunnels on the basis of environmental considerations whilst meeting safety criteria.
The TBM will be working mainly in sands under groundwater pressure head of up to 35m at depths down to 45m. Ground control will be carried out by pressurised slurry with air bubble regulation.
Bouygues and NFM (Framtome Group) refer to the TBM as "concentrated technology" due mainly to its sophisticated control and monitoring system.
