Author(s): Hege Lindbjor Nilsen; Knut V. Hoyland
Linked Author(s): Knut Hoyland
Keywords: No Keywords
Abstract: First-year ice ridges are important in the design of offshore and marine structures, but the knowledge about the ice ridge properties is still limited. Model scale experiments on artificially produced ice ridges have been developed, leaving the question of how to scale the properties correctly. This article concerns the scaling of the properties of the unconsolidated layer of the keel (the ice rubble) from model scale to full scale, as a part of the determination of ice ridge properties for design. Two types of punch tests have been simulated numerically in order to study the difference between the required material parameters: 1) Four full scale punch tests performed in the Gulf of Bothnia in 1999, and 2) Two model scale punch tests performed at the Hamburg Ship Model Basin (HSVA) in 2001. The experiments were modelled in the Finite Element software Abaqus, using explicit analysis. Both cases were modelled using the Coupled EulerianLagrangian (CEL) approach, which copes with the challenge of large displacements of the ice rubble as well as the interface between the puncher and the ridge. The ice rubble has been described by the Modified Cam Clay model, and the paper concludes a scaling of initial pressure by 20-40 from model to full scale. With a length scaling of around 10, this implies that model scale ridges are much weaker than full scale ridges.