Author(s): H. R. Kivisild; S. H. Iyer
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Keywords: No Keywords
Abstract: The recent discovery of oil and gas in the Canadian Arctic Archipelago and the coastal waters of Canada has stimulated the design of large offshore structures and transportation facilities. Accurate estimation of ice forces on these structures and their response are becoming necessary for safe and economical design. Because of a variety of ice features and ice conditions encountered, the analytical problems to be handled are becoming more and more complex. Basically, there are two approaches available for handling these problems: mathematical modelling and physical modelling of ice and the structure. Ice modelling is used for studying ice structure interaction and drift of floating ice sheets. Mathematical modelling involves considerations related to rheology of ice and failure criteria. Assumption of elastic, rigid plastic or viscous-plastic behaviour are made normally. Even though mathematical modelling is less expensive for ice-related problems, real-world conditions are difficult to simulate. Physical modelling then becomes a necessity to verify the proposed mathematical solution. In some cases, physical modelling becomes the only answer to the problem. For physical modelling to be of any significance, the modelling material should obey laws of similitude. This requires among other things, scaling of material properties. Weak ice and various other synthetic materials are being used. In all these materials, one or the other parameters are not properly represented to scale. However, it has been possible to use test results from models with correction factors applied to the model prototype correlations. As current prototype designs are materially different from earlier ones, correction factors established from previous experience are no longer applicable. The paper discusses the concepts of mathematical and physical modelling of ice, the rheological properties, the scaling problems, and materials used for modelling ice. The feasibility of using real ice and ways of overcoming distortions in similitude are discussed in detail.
Year: 1978