SEA Tours-Bordeaux HSL, France

Soil expertise serving high-speed rail 

The largest project of its type in Europe, the South Europe Atlantic high-speed line will reduce travel time between Paris and Bordeaux. Menard improved the ground under the backfill over a height of 5 to 10 metres for the northern and southern access to one of the project’s iconic structures, the viaduct over the Dordogne River. A number of clay layers were to be treated to a depth of about 12 metres below the roadbed, with anchoring in the compressible soils of former swamps. Nearly 8,000 Controlled Modulus Columns with a diameter of 320 mm and a total length of about 110,000 linear metres were installed. Thanks to the strong involvement of Menard’s design office, one of the major challenges of the project was addressed aligning the calculations with the technical specifications near the structure. Load tests ranging between 30 and 80 tonnes and mechanical impedance tests were carried out to ensure compliance with the most important criterion: less than one centimetre of total settlement under traffic loading over the next 25 years.