The purpose of breakwaters is to protect port infrastructures from waves. There are two main types of structures:
- Rubble-mound breakwaters, built with quarry materials and artificial blocks;
- Vertical breakwaters, mainly made of reinforced concrete caissons.
With its extensive experience in this field, Bouygues Travaux Publics is highly proficient in the construction of these two types of structure and offers innovative solutions during the construction phase, as in Calais, where the automation of the construction process for the rubble-mound has made it possible to limit the need for divers to work in difficult conditions.
Bouygues Travaux Publics’ added value also lies in its ability to optimise the design of structures. Over the course of many projects, the teams in the technical department have acquired a real expertise in the design of breakwaters, the monitoring and interpretation of model tests and calculations of wave agitation.
This experience and expertise allow us to assist our clients in their choice of construction of a rubble-mound or a vertical breakwater, or even a combination of both, in order to reach an optimum solution, technically and economically.
This global vision of designer-builder can lead, as it was the case for the Tangier Med 1 and 2 port projects, to completely rethinking the master plan of the port infrastructure project by taking into account all the expected functionalities (ease of navigation, protection against wave agitation) while optimising the breakwater structures.
Execution of a protective platform area and a counter-jetty
Construction of two fixed breakwaters on piles, a pontoon and the operations buildings of the new marina of Brest
A former military area returned to civilian use in 2005 as part of a plan to rationalise the property assets of the French Navy, the Port du Château brings yachts and sailboats into the heart of the city of Brest. To develop this marina, which has been designed to accommodate nearly 600 pleasure and racing boats, the maritime metropolis undertook colossal works in 2006. Two seawalls of 470 and 170 metres in length replaced the former breakwaters made of grounded navy vessels. They provide protection against the motion within the basin and offer, except when there are storms, a space for visitors to stroll. Adapting techniques from offshore construction, a first for a marina, the anchoring of the support piles for the southern breakwater was carried out by means of tie rods passing through the piles and fixed in the rock. 69 slabs weighing 70 tonnes each, prefabricated in the nearby commercial port, ensure the solidity of the southern and western structures. Concrete wave-guard walls, 13.45 metres high, complete the structure and protect the 11-hectare stretch of water, while limiting its silting up.
Design and construction of the Tangier port and its extension
Until the end of the last century, Oued Rmel, 40 kilometres east of Tangier, was a sandy beach set against the desert, exposed to both the Mediterranean and the Atlantic swells. Since then, container ships from all over the world have been coming to this port that has enabled Morocco to establish itself as one of the world’s maritime trade hubs. In a consortium with BYMARO, a subsidiary of Bouygues Bâtiment International, Bouygues Travaux Publics was entrusted with the design and construction of the Tangier Med 1 port. The chosen option involves a combination of breakwaters made of accropodes™ and absorbent caissons depending on the depths. This optimises the mass layout and offers an additional 14-hectare platform. The caissons were built using sliding formwork on land before being launched, and are composed of over water chambers with perforated walls on the sea side to reduce the impact of waves and to limit over topping. This port extension included the construction of two new mixed breakwaters using embankments and caissons, as well as 1,200 metres of quays.
Design and construction of a ro-ro port to accommodate ships
After participating in the construction of the strategic port of Tangier Med 1, Bouygues Travaux Publics was entrusted in a consortium with BYMARO, with the design and construction of the city’s new port terminal for roll on/roll-off ferries (ro-ro). The alternative plan made it possible to offer ships a greater ease of navigation and to favour a radial layout around the entrance channel. Two breakwaters of 1,230 and 1,200 metres in length, eight berths for ferries consisting of quays blocks and mooring dolphins and a 42-hectare logistics platform were built. The main breakwater is made up of two sections: a first section with an embankment, protected by a shell made of accropodes™, and a second section made up of 23 reinforced concrete caissons, that were prefabricated and then immersed. The use of prefabricated caissons permitted the shortening of construction time and a narrower breakwater to be built. This lowered the environmental impact of the project, thanks to a reduction of the site footprint and volume of materials used.
Dismantling and reconstruction of a mole
As a fishing port hosting some 60 vessels that unload 10,000 tonnes of fish and shellfish each year, the port of Erquy is vital to the maritime economy of Brittany. In order to carry out the renovation and extension operation commissioned by the Côtes d’Armor department, it was necessary to simultaneously dismantle the existing mole, which had been damaged by the elements, and the reconstruction of the replacement mole, without jeopardising the port’s protection against swell. This extension provides an additional 4-hectare stretch of water and new quays. To minimise the impact of the work on road traffic, particularly during summer, a concrete plant was installed on site and materials were transported by sea from nearby quarries. A concrete, whose tints resemble those from the Pink Granite Coast, was used.
Execution of the port extension works
The port of Port-La Nouvelle, located in the Aude department, is the third largest French port in the Mediterranean. As part of its Plan Littoral 21 port development strategy, the Occitania region has engaged in a project to extend the port of Port-La Nouvelle in order to further the development of maritime traffic and host new industrial projects related, in particular, to renewable marine energies. The works led by Bouygues Travaux Publics include the construction of a new port basin consisting of two rubble-mound breakwaters, 600 and 2,430 metres long, as well as the construction of quay site and the northern platform of 4.5 hectares within the basin. Built from riprap, the seawalls are reinforced with a shell of prefabricated accropodes™ built on-site. These extremely strong concrete blocks are designed and scaled to resist wave action on the breakwaters and break the energy of the swell. The new harbour basin will accommodate the new generation of 225-metre-long and 36-metre-wide ships.
Design and execution of the port of Calais extension works
With a high growth in cross-Channel traffic being expected by 2030 and increasingly long ferries, the Port of Calais decided to anticipate these developments by launching Europe’s largest port infrastructure project, “Calais Port 2015”, in 2015. This large-scale project included the creation of a 177-hectare basin and a 90-hectare dock, protected by a breakwater more than three kilometres long, the construction of three new berths for ferries and the development of 65 hectares of platform area – including 45 hectares reclaimed from the sea. The construction of the breakwater required the installation of nearly 17,000 Xblocs®, cast concrete block from 4 to 12 m³, whose X-shape and interlocking structure are designed to resist swells while dissipating wave energy. Manufactured in an automated factory, built on site and specially designed for the worksite, the Xblocs® are installed using two techniques: an echoscope and the POSIBLOC™ system, which consists of cells incorporating a GPS beacon, temporarily fixed to each Xbloc®.