The works for the extension of metro line B at Oullins station started in july 2009. They were due to be finished by the end of 2013. The project consists in the excavation of a single tube tunnel 1.7 km long, requiring the underground crossing of the Rhône river. The single tube will enable twy-way traffic flow.
This tunnel is bored by a group of contractors lead by Chantiers Modernes (Vinci group). The excavation itself started in September 2010 using a TBM with 9.5 m of diameter, allowing the creation of a tunnel with 8.35 m interior diameter. The tunnel is bore 17 m belowr the Rhône river bed (at the deepest point), i.e. 35 m below Rhône river water level, in soils made of alluvium and molasses. On march 2nd 2011, the TBM reached the Oullins-station, after a 5-month excavation. Beyond the line terminus, the TBM has also bored a 300 m tunnel in granite for station facilities.
Terrasol got involved in different phases of the project:
- In 2005, in the frame of the preliminary studies for Sytral with Setec TPI,
- In 2008, for assistance to a group of companies during the call for tenders phase,
- In the frame of detailed design: finite element calculations using CESAR-LCPC software. Evaluation of surface settlements for 12 calculation profiles, includingfive monitored sections with parametric studies relating to confining pressure, and back-analyses,
- During the works: participation of Alain Guilloux to the experts committee set up by the group Vinci / Spie.