Sealing of stress cracks, Øresund Tunnel

Technical challenges during the construction of the Øresund Tunnel
One of the major technical challenges during construction was the so-called sinking method, in which 20 caisson elements, each 176 meters long, were manufactured and then sunk into the sea. This method is also being used in the construction of the Fehmarn Belt Tunnel.

Preparation and manufacture of the tunnel elements
The tunnel elements were manufactured in a specially equipped production area. For each element, around 2,700 m³ of concrete was processed in a single operation within just 40 hours. In order to avoid stress cracks as far as possible, the work was carried out in huge production halls at a constant temperature of around 20 °C, which contributed significantly to quality assurance.

The lowering process
In the so-called lowering process, the tunnel elements, which had been manufactured in a dry dock, were lowered into the water in a controlled manner. They were then precisely positioned on a prepared gravel bed using state-of-the-art satellite navigation. The elements were then connected with in-situ concrete to achieve a long-term stable and resilient construction.

Post-construction sealing of stress cracks with WEBAC products
Despite the careful processing of the concrete, stress cracks could not be completely prevented. These were post-construction professionally sealed and injected with WEBAC PU injection foam resin, which was specially developed for these requirements, and WEBAC 1405, which is tested in accordance with ZTV-RISS. These post-construction injection measures ensured that the structure remains permanently watertight, stable, and reliable.

The successful use of modern construction and sealing methods ensured the long-term stability of the Øresund Tunnel.