Foundation optimisation for the new 4.0 km long Storstromsbroen in Denmark - Challenges in the design of highly loaded caisson foundations in ,Danish Glacial Till'

The new 4.0 km long Storstr & oslash;msbroen, currently under construction, is a multimodal bridge that combines a double-track high-speed railway line with a road on a common superstructure cross-section and will connect the Danish islands of Falster and Sj ae lland, thus forming an integral part of the future high-speed railway link between Copenhagen and Hamburg. The bridge will be Denmark's third longest bridge, only exceeded by the Oresund Bridge and the Storeb ae lt Bridge. The foundations of the 44 bridge piers and the central 103 m high pylon of the cable-stayed bridge are mainly made of large prefabricated caissons, which are laid as shallow foundations over thick gravel base layers on the seabed in the pre- glacial clay till. In addition, ground improvement with rigid inclusions is also used at some axes. The paper reports on the key geotechnical challenges in the design and optimisation of the highly loaded shallow foundations in the over-consolidated ,Danish Glacial Till'. In the process, approaches that go far beyond the usual design practice, such as the consideration of non-linear global foundation stiffnesses, dynamic highly nonlinear analyses on the overall model and the acceptance of irreversible plastic displacements, were used to sustainably optimize the dimensions of the large spread foundations, which are subject to highly eccentric loads due to traffic loads, ice pressure and ship impact, among other actions.