The Lyon-Turin link is a new railway line for goods and passenger transport stretching 270km, 70% in France and 30% in Italy. TELT (Tunnel Euralpin Lyon-Turin), a bi-national Franco-Italian public property development company, is in charge of building and operating the 65km cross-border section between France and Italy, the major structure of which is the 57.5km tunnel at the foot of Mont Cenis, linking Saint-Jean-de-Maurienne (Savoy) and Susa (Piedmont).
The entire project, entrusted to the LYTO consortium (VINCI Construction Grands Projets, Dodin Campenon Bernard, Campenon Bernard Centre Est, and WeBuild) and Bergteamet two years ago, involves the construction of:
Technically, it should be noted that the tunnel is partly ventilated by four shafts in the commune of Avrieux at 1,305m altitude. Excavation of these 500m-deep shafts, using the raise-boring technique requires consolidating and sealing the rock for the first 135m.
In order to implement the best possible soil treatment, several drilling and grouting test plots were carried out. It should be noted that this type of work is very unusual, with major technical requirements including the vertical nature of the boreholes and the grouting of several grouts with variable viscosity.
The first rock-treatment phase between 0m and 70m has been completed and the deep grouting (70m to 135m) are now in progress.
This operation, requiring three drilling workshops in three positions, will take several more months to complete and to secure the execution of the work of raise-boring.
For our teams, this is a complex project with many technical and environmental requirements.
In fact, before the beginning of the works, an acoustic and thermal shed has been set up to protect the environment from noise pollution and allow the teams to work sheltered from the region’s harsh weather.
The project was also subject to a major environmental requirement in terms of water treatment, with water having to be recycled rather than discharged into the natural environment. To do this, Soletanche Bachy set up a worksite water treatment plant which operates according to the following principle: