Project - AQUA-Shell: a special technique for the construction of quay wall capping beams

AQUA-Shell: a special technique for the construction of quay wall capping beams


 
Project description

A recurrent problem in building quay walls in offshore conditions is the construction of the concrete capping beam. These capping beams usually reach below the water surface and hence must be cast below the water level. An unconventional shuttering technique is applied in the construction of a quay wall in the Port of Antwerp, named The Aqua-Shell.
The Aqua-Shell is used to create a dry environment to pour the capping beam of a quay wall. After the Aqua-Shell is placed against the quay wall it is pumped dry so it will pressed up against the quay wall just by the use of water pressure on the outside of the Aqua-Shell. The upward forces on the Aqua-Shell due to the water pressure are passed on the quay wall by use of a specially designed connection which can be re-used during the project.
The design of the rubber profile for the watertight sealing was one of the challenges during this project. The caisson had to be watertight at all times considering a drive tolerance of 80mm on the steel tubular piles.

To make the Aqua-Shell transportable by road it can be dismounted into two parts.
The design and engineering of The Aqua-Shell is done by MH Poly Consultants & Engineers BV. The construction is entrusted to Van Laere General Contracting N.V..

Construction of the quay wall

The new quay wall has the length of approximately 860m and is built up from sections of 20.10m each. Each section consists of a combi-wall with 6 tubular piles, sheet piles in between, and a capping beam 4.36m wide and 3.52m high. This construction is then anchored by means of 31m-long MV-tension piles.
Some indicators for the construction
- 267 steel tubular piles, diameter 2,032mm, thickness 22mm, length 26.8m;
- 262 MV-piles HP360x174 (HISTAR 460), length 31m;
- 268 double sheetpiles AZ26 (S355GP), length 20.8m;
- 4,000m3 reinforced concrete;
- 1,500 tonnes rebar steel and 13,00m2 formwork.