Antwerp Dry Docks – Restoration of a dry dock pt. 2

 In Renovation

The Antwerp dry docks in the Hansadok are together with the city dry docks near the city the only remains of 200 years tradition of ship building and restoration in the port of Antwerp. EDR, together with the Port Authorities, hope to transform the site into a new and modern shipyard after years of decay. SBE oversees the entire renovation of the site with 3 wet docks, 6 dry docks, warehouses, offices, workshops, cranes, etc.; from master plan to detailed civil and mechanical engineering.

Dry dock 5, the second largest and newest dock, is the first to be restored. Its construction dates to the sixties and the dock is 240 m long, 40 m wide and 9 m deep.  A dry dock is basically a U-shaped box. The walls are quite similar those of a lock. Here the walls are constructed as massive gravity walls that can withstand both the soil and water pressure. The floor is a thick concrete slab because it must also serve the secondary function of acting as a platform to fix the vessel and to repair it. In the walls, two tunnels run along its entire length. The lower tunnel serves as a drain and the top tunnel is a service tunnel for piping and inspection.

Section of the dry dock concrete walls

In a previous post we elaborated about the extensive test campaign that preceded the design of the renovation of the concrete walls. Given the condition and the new increased loading, it was decided that the roof of the service tunnel had to be completely renewed. The upper part of the walls (roughly 0.75m in height) will be demolished over the complete width and length of the wall. It will then be completely rebuilt with new reinforcement. It will be chemically anchored into the existing wall making use of drilled in bars.

Considering the age of the existing structure, some specific problems had to be solved. One of them was the shrinkage of the new concrete that introduced immense tensions in the existing structure. This structure was not adequately reinforced to cope with this tension. This would lead to severe cracking. Therefore, a creative solution to avoid this tension was implemented. A prefabricated slab absorbs the main part of the tension without transferring it to the existing concrete structure.

Another problem was the density of the reinforcement of the new concreted zone. Due to heavy loads (vehicles, winches, …) on top of the walls, a substantial amount of rebars and anchors had to be placed in this zone. With the help of a BIM-model of the entire dock that included both civil, secondary and mechanical components in detail the reinforcement was also designed in 3D. This enabled the tracking and solving of possible conflicts and the optimisation of the reinforcement scheme.

Renovation of the service tunnel walls

The rest of the structure was in better shape. The walls of the service tunnel were only slightly renovated by removing the outer layer of concrete, cleaning and applying a protective coating on the reinforcement and a repair mortar. Finally, after the cleaning of the concrete structure; local damage will be repaired with a mortar.

Views in the BIM:

BIM - View on dry dock 5
Location of Dry dock 5 on the Antwerp dry docks site

Do you want to read more about the concrete test campaign conducted in Dry Dock 5? Click here.