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Strukton lays the foundation for the longest suspension bridge in the world

19 July 2018

Near the Turkish city Çanakkale, the Çanakkale 1915 bridge is being built. The new mega bridge will soon be the longest bridge in the world with a main span of 2,023 meters between the two pylons. Strukton Immersion Projects literally lays the foundation for the huge bridge that will be opened for traffic around 2023.

Canakkale bridge 

The Çanakkale 1915 bridge is part of the Çanakkale-Tekirdağ-Kınalı-Balıkesir highway project and will be 3.6 kilometers long, with another 800 meters to be built inland. With a huge head span, the new mega bridge surpasses the current record holder - the Akashi-Kaikyo Bridge in Japan, with a main span of 1,990 meters. The Çanakkale 1915 bridge will soon replace a number of ferry services over the Dardanelles, the narrow strait along the Bosporus. The construction of the bridge was granted to a joint venture consisting of two Turkish and two Korean companies, which in turn engaged Strukton's expertise in placing the bridge foundation. 

Foundation construction

The new bridge will soon be connected to two pylons above the Dardanelles. "It is up to us to drag the two caissons that serve as a foundation for the pylons and to sink them on location," says Peter van Westendorp from Strukton. "Both caissons are built by the joint-venture on a dry dock location at the riverbank, especially designed for this project, about 4,000 meters from the sinking location. The concrete caissons are hollow, with a floor area of ​​74 by 83 meters and a height of 20 meters. The caissons will be finished as much as possible in the dry dock so that they can still be dragged to the mooring location. Complete finishing in the dry dock is not possible due to the limited draft. At the mooring location, for each caisson, two more towers are placed in double-walled steel with a diameter of 18 meters. All facilities for the ballast system are also installed by us. The total height of the foundation construction is more than 45 meters, with the four towers (two per caisson) sticking just above the water surface after immersion. The joint venture then continues to further build the pylons."

Canakkale_caissons_paleis2
Canakkale_caissons_paleis

 

Ballast system

Strukton therefore does not interfere with the construction itself. However, it does with the engineering of all facilities needed for the transport, mooring and sinking of the caissons. "We are responsible for transporting the caissons to the mooring and sinking location and are also taking care of the sinking process," says Van Westendorp. "The ballast system in the hollow elements is completely developed and built in by us. The caissons are internally provided with a grid of compartments for the sinking to take place as controlled as possible and to be able to influence the position / inclination. We have to deal with a tolerance of plus or minus 20 centimeters at a water depth of about 42m. Very small.

The caissons will later on be standing on a gravel bed on the seabed that is provided by the joint-venture. Van Westendorp: "Next to the gravel bed, a guide construction we be placed on two sides of the caisson so that we can still fine-position the caisson with jacks before touch down. Towage and coarse positioning takes place with four tugs. Two tugs are attached to pre-installed anchors. The other two tugboats will be kept in position by means of their dynamic positioning system. The immersion is done by filling the caisson with water in a controlled way. Once in position, the clusters of the caissons are completely filled with water, about 35,000 m3. "For the entire operation, from towing from the mooring location to the complete filling, Strukton has 72 hours. According to plan, both caissons will be submerged in January - February 2019.

Source: GWW Magazine 
Article in Dutch