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Inauguration of the port parking lot in Saint-Jean-de-Luz

December 22, 2023 saw the inauguration of the Saint-Jean-de-Luz parking lot built by teams from Soletanche Bachy France. Special technical solutions were proposed to build this structure in the flysch of the Basque coast.

The Saint-Jean-de-Luz parking lot is located on boulevard Victor Hugo and will create 427 spaces spread over 5 levels. An ambitious project on the Basque coast, perfectly executed by teams from Soletanche Bachy France in a consortium with Eiffage Construction Sud Aquitaine (leader).

Tools specifically designed for this type of soil

This site is unusual in that the subsoil of the Basque coast is composed of flysch . Flysch is an alternation of sandstone and marl beds, a type of hard rock. The bedrock is topped by around 30 m of alluvium consisting of sands with clayey and muddy passages, followed by clean sands.

To create diaphragm walls in this type of ground, the Soletanche Bachy France teams used Twinsol® tooling. The Twinsoil® concept is based on the ability to fit a KS hydraulic grab and Hydrofraise® circular drums on the same crane, both of which are easily and quickly interchangeable depending on the terrain to be traversed.

A total of 28 diaphragm walls, 80cm thick and 33m deep, were built, along with 6 barrettes. In order to maintain the structure, supporting beams were installed, they act as permant struts for the diaphragm walls and serving as the load-bearing structure for the parking levels. In all, 7,000m² of diaphragm walls and barrettes were installed.

To ensure the stability of the structure and avoid temporary struts, a “racecourse” shape was chosen for this structure. The fact that there are no structures at the ends during the provisional phase improves the organization of the worksite and enables the civil engineering to be carried out in the open air, which is less constraining.

This project is an environmental bonus, as it will reduce traffic in the city (40% of which is affected by the search for parking spaces). The first level of the parking lot will also house a dedicated bicycle parking area and electric charging stations!

Congratulations to the Soletanche Bachy France teams on the completion of this project, with its high level of design and construction methods!

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