As many as 12 foundation tiles will be installed for the two tunnel elements, which will be immersed in spring 2023. The foundation tiles weigh about 95 tonnes each and 4 foundation tiles have a size of 7 x 7 metres and 8 foundation tiles have a size of 6 x 6 metres. For placing the concrete foundation tiles, DEME and W. Smit BV, among others, are cooperating. After the foundation tiles are placed, divers will disconnect the lifting equipment at a depth of about 30 metres and then prepare to place the next foundation tile.

Tides and currents at this location make placing the foundation tiles extra challenging, but still manage to place the foundation tiles on the bottom within a few centimetres tolerance. GEOCON is used to determine the position of the tile. For this purpose, the system is duplicated. Both GPS and measuring prisms are used to determine the location and orientation.

SImP has extensive experience in placing the foundation tiles on the ground. Foundation tiles were previously placed by Strukton for the Limerick Tunnel and the North/South Line IJ Tunnel, for example. The gigantic concrete foundation tiles are laid with the accuracy of a few centimetres.

Placing the foundation tiles on the bottom is one of many preparations for sinking the two tunnel elements of the Maasdeltatunnel. The two tunnel elements will be immersed in spring 2023. The Blankenburg connection will make it possible to drive from the A20 near Vlaardingen directly to the A15 in the Botlek.

One special technique that was used is the immersed tunnel technique. This technique has been used for the crossing of the IJ-river under very soft soil conditions and for the crossing of the historic Amsterdam Central Railway Station. The application of the immersed tunnel technique underneath a historic building has never been applied in the world and was a true challenge considering the special immersion trench that had to be created underneath the building. The tunnel was successfully immersed under the Central Station in the summer of 2011. This paper will focus on the technical challenges of the complicated underpass of the historic Central Railway Station and the IJ-river crossing.

This paper will focus on the immersed tunnel part of the link and the particular challenges that the project faced in designing and constructing the  tunnel, these challenges required a significant evaluation in immersed tunnel technology. The tunnel consists of 18 tunnel elements and has a total length of 3.6 km. The tunnel location was characterised by the following conditions:

• a large depth, maximum depth of the tunnel is 48 m below sea level.
• the tunnel is located in a seismic sensitive area.
• the tunnel is founded largely on weak marine clay, but parts also on bedrock.
• part of the tunnel was constructed on a sub sea embankment which is also founded on a weak marine clay.
• the tunnel has been constructed in a location that is facing to the Sea of japan and is exposed to a severe wind and wave environment with large long period swell waves present for part of the year.

Strukton Immersion Projects has taken the initiative from the Working Group 11 (Immersed and Floating Tunnels) of the International Tunneling and Underground Space Association (ITA) to develop a stand together with partners for this exhibition that promotes the immersion of tunnels and caissons. We will be on this stand together with fellow companies that are also closely involved in the Working Group 11.

Strukton Immersion Projects recently floated out the tunnel elements of the Blankenburgverbinding and towed them out of the Keppel/Verolme construction dock. Strukton Immersion Projects will immerse these tunnel elements in March/April 2023. Strukton Immersion Projects is also working on the highway tunnel under the Schelde for the Oosterweelverbinding in Antwerp. This concerns the transport and immersion of 8 tunnel elements.

The magazine E-mosty published an article about the work carried out by Strukton Immersion Projects. The complete five-page article can be found here.

The Maasdeltatunnel forms the link between the north and south banks of the Blankenburgverbinding. Two tunnel elements will be immersed in the river Het Scheur at a depth of 28 meters below sea level. A tunnel with a story, a construction of Dutch Craftsmanship.

The biggest challenge within this project is the immersion of the two tunnel elements, which together form the Maasdeltatunnel.

In a dry dock, a stone’s throw from the construction site in Rozenburg, BAAK built two tunnel elements of approximately 200 meters long, 42 meters wide and 8 meters high. In order to make the tunnel elements watertight, Strukton Immersion Projects provided the four tunnel bulkheads. The modular steel bulkhead panels were placed in the openings with great precision. This precision is crucial because the smallest imperfections can lead to leaks.

After installing all mooring wires and winches, everything was carefully and extensively checked against checklists. A GO during the Go/No Go meeting was the signal to fill the construction dock with water. During the filling process, continuous checks were carried out in the tunnel elements and the tunnel elements were floated up in a controlled manner. With two tugboats the tunnel elements were transported to a temporary mooring location. The floating up and transport was carried out with precision and craftmanship by the team of specialists from Strukton Immersion Projects and DEME Infra.

The tunnel elements will remain at the temporary mooring location awaiting the immersion. In 2024 the final result will be a 924-meter tunnel for traffic between Rozenburg and Vlaardingen.

(Source: among others Rijkswaterstaat, Ballast Nedam, DEME Infra)