On the prediction of global first-year ice loads

다국어 초록 (Multilingual Abstract)

A model and associated computer program was developed for a deterministic prediction of global first-year ice loads on offshore structures. The load caused by a ridge consists of load components arising from a consolidated layer, a rubble pile that develops in front of the structure and of the ridge keel. The ridge keel is considered as a layered accumulation of ice rubble, below the consolidated layer. The uppermost layer of the ridge keel can have a high apparent cohesion strength, due to ice blocks that are partially frozen into the consolidated layer.<br/>
A soil mechanical approach is used to simulate the changes in the keel profile when a structure penetrates the ridge. Both vertical and inclined structures can be considered by the present model.<br/>
A parametric study was made to determine how some of the uncertainties of the input parameters influence the global load evaluation. Therefore, it should be appreciated that the example calculations shown above do not represent actual ice load predictions for the example structure considered. It was found that the present lack of knowledge about the internal friction angle of the ridge keel represents a major source of uncertainty in ice load prediction. The computations also showed that the layered structure of the ridge keel may influence the keel load component considerably. The frictional resistance that develops at the rubble/structure contact area causes an increase in the ice load. The inclination of the structure has the same effect if the ice wall forces the ice rubble upwards during ridge penetration.