Separation wall protects current Coentunnel

With the constructing of the second Coentunnel, a separation wall provides protection to the integrity and stability of the existing Coentunnel. The separation wall is applied with a vibration-free method from a fri anchor pontoon combination in the North Sea Canal.

Applying the separation wall

The separation wall is made by the company Foundation techniques Verstraeten, better known as foundation specialist Fundex. The method was pre-tested on the land. Implementation of the separation wall in the North Sea Canal had as complication that the wall had to be applied submerged and 2 meters below the channel bottom.

The wall consisting of a combi-drilled wall of steel tubes with a diameter of 1.5 meters, separated by a double sheet shelf. To ensure that the construction of the separation wall did not influence the current location of the Coentunnel, a low-vibration method of implementation was used: the piles of about 20 meters long were dashed. This avoided disturbance of the vibratory pile driving or working in the sensitive layer of the coil of the current Coentunnel consisting of loose sand.

Coentunnel

The Coen is the main connection in Amsterdam under the North Sea Canal. The tunnel forms a bottleneck between the areas north and south of the canal. Every day there are traffic jams. To guarantee the flow in the future to the existing Coentunnel RWS decided to build a second Coentunnel. The second Coentunnel will be sunk into a dredged trench next to the current Coentunel. Because the second Coentunnel will be no more than 12 to 14 meter next to the current Coentunnel, it is necessary a protective wall, a separation wall to be applied between the existing tunnel and the trench that has to be dredged. This ensures the integrity and stability of the current Coentunnel during the construction of the second Coentunnel. The wall is to be stable and solid after dredging the trench.

[Source: vakblad Land + Water]