CEL-analysis of punch shear tests to evaluate mechanical properties of ice rubble

Drifting sea ice ridge introduces often a major load scenario for the design of offshore structure. Major load contribution is presented by the consolidated layer and the underlying keel. Mechanical properties of the ridge keel are essential input to predict ridge loads.In a punch shear test, a circular platen of consolidated layer is first cut free from the surrounding ice field. Thereafter, the platen is pushed down to break the underlying keel. The measured load-displacement relationship can be used for the evaluation of rubble properties and also for the model validation. Ridge keel punch tests were carried out in the Bothnian Bay 1998-2003 with various platen diameters and keel thicknesses. This data has been earlier studied by the finite element simulations in Lagrangian framework. Presently, Coupled Eulerian-Lagrangian (CEL) framework was applied. The main benefit of CEL is that it enables robust modelling of large deformations due to material failure during the punch load. The ice rubble was modelled as a continuum with a shear-cap failure criterion, which describes both the shear failure and compaction. Parametric studies were carried out for two punch shear tests to determine the rubble properties. Main objective was to evaluate a suitable combination of the cohesion and friction angle which can be further utilized in ridge load analyses.