THE GREAT BELT LINK
In 1987, Geo performed a long series of geotechnical investigations for the new Great Belt link: a combined road- and railway connection. Due to the inclination of the High Bridge, it would be both costly and difficult for trains to pass the High Bridge. As an alternative, it was decided to build a railway tunnel, providing a much better technical solution. However, the bored tunnel below the Østerrenden in the Great Belt also proved to be the largest technical challenge for the Great Belt link, because it was, among other reasons, the first of its kind in Denmark and required groundwater to be lowered beneath the seabed, in order to ease and facilitate tunnelling operations. The dewatering project was named, quite aptly: Project Moses. Geo was responsible for Project Moses and managed both consultancy and dewatering. Furthermore, Geo was the initiator of the project, executed all borings along the train route and managed both design and installation.
The tunnel, however, was not the only challenge. Also founding the large pylons and anchor blocks on moraine clay created challenges for Geo’s geotechnical engineers. Therefore, Geo performed newly designed large-scale dynamic plate load tests and sliding tests on the moraine clay at Halsskov Ferry Harbour and near Sprogø. Just west of Sprogø, the moraine clay was discovered to be exceptionally weak, which had to be taken into consideration in the design of the pillars for the western bridge, between Sprogø and Funen.
Furthermore, Geo performed preliminary investigations for the so-called compensation excavations, because the Construction Act determined that the link must not influence or indeed change the water flow in the Great Belt. In order to ensure water flow, some of the seabed was excavated.