By Lynda Myer
The digging process of the Lyon-Turin base tunnel in Saint-Julien-Montdenis on construction site n.08 in Villard-Clément has been started now, while around 3 km of tunnels are due to join the 10.5 km already built between Saint-Martin-la-Porte and La Praz.
As a new phase in the construction of the cross-border section of the Lyon-Turin railway line, commencement of underground work on the construction site n.08 is a further step forward following sign of the tenders for the construction of the base tunnel on the French side, worth EUR3 billion, in 2021. With intention of inaugurating the in 2032, the next award of the contracts for the Italian side of the base tunnel in 2023 will put the construction phase in a new stage.
The Lyon Torino CO08 enterprise grouping, which is composed of Implenia Suisse (group head), Implenia France, NGE Génie Civil, Itinera and Rizzani de Eccherm, as well as the Inalpage construction management group that is composed of the following contractors: Egis structures et environment (head group), Alpina, Ingerop Conseil et ingénierie and Geodata, are the involved companies in this area, where between 2018 and 2021 the works of the cut-and-cover tunnel, i.e. the French entrance portal of the tunnel, were carried out.
As the preparatory works for this project, in order to reaching the base tunnel depth, the land was dug, extension of the high retaining walls have been implemented and the soil, where the tunnel is due to be excavated, has been reinforced by concrete injections (using the jet grouting method). Additionally, for the smooth operation of the construction site, total of the significant installations such as the concrete plant and the water treatment station, are operational. Meanwhile protecting the residents from noise during the entire construction period was done by installing an acoustic hangar. Finally, using a conveyor belt all dug material are slated to be transported to the Resses site in the municipality of Villargondran.
Benefiting the traditional method, the 2.8km two tubes of the Mont Cenis base tunnel will be tunneled in this 24 h/7 days a week construction site, whereas this building will be towards the Saint-Martin-la-Porte access tunnel, where the Joint Venture led by Vinci Construction is continuing with the installation of the 06/07 operational construction site (23 km between Saint-Martin-la-Porte and Villarodin/Bourget-Modane) and the preparatory activities, awaiting the arrival of the TBMs that is going to dig the base tunnel from 2024.
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