ABSTRACT

In this paper, explanations to a few of the many unresolved issues on ice-structure interaction problem are presented. Explanation to why the laboratory indentation pressures are larger compared large scale indentation tests are provided. Using dimensional analysis and similarity theory approach in conjunction with experimental data, it has been explained as to why velocity of indentation should be considered for ice interaction with structures to reproduce all the physical processes/phenomena both in proto-type and model systems and, to ensure that the results would have one to one correspondence, without any "scale effects", (different from size effect) being introduced. It has been shown in this paper that for any given dimensionless strain-rate (u2/gℓc), the dimensionless pressure (Pe1u2) would decrease with increasing aspect ratio (B/ℓc); that for any given aspect ratio, while the dimensionless pressures are very high at lower dimensionless strain-rates it gradually decreases, even for laboratory conditions as the dimensionless strain-rate increases. Using a limited number of numerical results for ice indentation on a 2-D structure under plane-strain conditions, where rate effects or velocity influences are considered (elastic-visco-plastic models), it has been shown that for the same dimensionless strain-rate and aspect ratio, the computed values are at least an order of magnitude less than that predicted by our model, which is based on experimental data. Example calculations, using the figure generated through the application of dimensional analysis and similarity theory are presented in tabular form, giving both dimensionless and dimensional pressures, for some well known laboratory and field tests using the input data from these tests.

INTRODUCTION

Ice structure interaction processes are complex and the influences of various parameters defining the processes are not fully understood. Consequently, available methods for estimating ice forces on structures, which are too numerous, are not precise and there had been a significant level of uncertainty and even confusion on the amount of ice-induced forces on structures.

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