Sammendrag
The number of offshore structures built in ice-covered waters has increased during the past decades, with the search of profitable resources being a major contributor. The interaction of these structures with an ice feature is an inevitable occurrence and they ought to be designed accordingly. However, this interaction is a complex scenario, where a large number of mechanisms are involved. The determination of global forces and pressures, as well as the effect of the different elements involved, remains a subject of research.
In the present thesis, the Coupled Eulerian-Lagrangian (CEL) analysis technique is employed in a Finite Element (FE) model for the numerical simulation of the interaction between ice and a fixed structure, in order to investigate the effect of the aspect ratio on the global pressure, as well as the influence of ice properties. A quasi-static analysis is performed, by means of a fixed, cylindrical, fully rigid structure. The ice feature considered consists of a smooth, large, level ice field which moves at a constant speed. The use of CEL is favored by its capabilities for modeling contact as well as for naturally dealing with large deformations. The test method consists of running several CEL simulations, either varying the structure size or modifying ice properties. Three material models are used for ice: perfectly plastic, Drucker-Prager with a cap and a concrete damaged plasticity model.
Results show in general a good agreement in terms of effective pressure and forces, and a size effect is also simulated. In addition, the phenomenon of buckling is captured for the larger aspect ratios. Strength-related properties are concluded to contribute the most to changes in the interaction outcome.