The France Digues (France Dykes) association records more than 6,000 km of dykes in France. ArcelorMittal's steel solutions are regularly selected for dyke extensions and reinforcement projects.
Dyke reinforcement at St-Laurent-du-Var (France)
The Flood Risk Prevention Plan (PPRI) for the lower valley of the Var River highlighted the need to review the flood defences of the town of Saint-Laurent-du-Var. This resulted in a revision of the Flood Prevention Action Programme (PAPI) to include works which will protect an additional 1,100 linear metres of the dyke. The work will protect nearly 2,000 inhabitants, a small business area, sports and cultural facilities, and the town centre.
Reinforcement of the Saint-Laurent-du-Var dyke affects both banks. The work, which is bordered by metropolitan route 95, covers a linear distance of 1.6 km.
The reinforcement uses a double-wall of sheet piles for sectors of the embankment with sufficient distance between the road and the dyke. AZ 23-800 sections in lengths ranging from 12.7 to 14.5 m are used for the main retaining wall. AZ 18-800 sections in lengths from 2.5 to 7.5 m are used for the anchoring wall. The steel grade used is S355 GP with a total weight of 2,315 tonnes.
Rehabilitation of the Fouchy dykes in Troyes²
At the heart of Troyes metropolitan area is a network of canals running for around 130 linear kilometres. The presence of the canals makes the area a ‘little Venice’. A project to rehabilitate the Fouchy dykes protecting Troyes was launched following a safety assessment carried out in 2011. The rehabilitation of the dykes is one of the latest phases to be implemented. The project included the use of ArcelorMittal's HZ®/AZ® combined wall system.
Setec Hydratec and GEOTEC, the project's designers, chose ArcelorMittal’s sheet pile solution for sectors where a 2H/1V embankment would excessively encroach on the river's hydraulic section. The VINCI Construction and LEDUC TP consortium proposed and implemented modern, high-performance sheet piles using 800 mm wide AZ 18-800 sections to form self-stabilising curtain piles. The solution has proved to be both optimal and economical while meeting the demands of the Fouchy dam. To limit deformation of the highest parts, the consortium installed a curtain composed of HZ®-M profiles. This material gives the screen the necessary inertia to limit its deformation.
The AZ 18-800 sheet piles and HZ-M sections were manufactured in Luxembourg from 100-percent recycled steel. This limited emissions from transport and the overall environmental impact of the project.
²SolscopeMag n°16 from November 2020.