This paper presents the results of numerical simulations which examined the interaction between two types of offshore structures and unconsolidated first year ice ridges. The types of structures modelled were a simplified spar and a Floating Production Unit (FPU). The spar was modeled as a downward breaking cone with a cylindrical neck. The FPU had an inclined cylinder for the bow and an inclined plane at the stern. A computer program based on the discrete element method was used for the analysis. The ridges were simulated by allowing ice pieces with random initial orientation to float towards the water surface. The structure transited the ridge with a steady advance velocity. Time histories of the interaction forces between the structure and the ridge were calculated (in three orthogonal directions) and the distribution of the ice floes around the structure during the interaction was visualized. Two ridges were simulated for each structure, with nominal keel depths of 6m and 15m. The effect of ice properties, such as ice density (relative to the surrounding fluid) and some of the internal coefficients within the discrete element code were varied. The simulations were compared to the physical model experiments for the same structures and the results showed that the discrete element method provided an acceptable estimate of the ice forces interacting with the two different types of floating structures. The simulated movement of the ice around the structures also showed good agreement with model experiments for both the types of structures.
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