Author(s): Shanshan Sun; Hayley H. Shen
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Keywords: No Keywords
Abstract: Due to the reduction of sea ice in the Arctic, future offshore exploration activities are expected to increase. The increase of open water area, particularly in the summer season, will likely create unprecedented wave conditions in this region. It is known that ice covers produced in a wave field, unlike that formed from a pure thermal growth under a quiescent condition, usually consist of an assembly of floes with strikingly uniform shape and size. This type of ice is approximately circular in shape, thus called pancake ice. In this study we report the results of a numerical simulation using the Discrete Element Method (DEM). With the model described previously for different applications, we examine the impact load of a field of pancake ice under various wave conditions on a fixed circular cylinder built into the sea bed. The dependence of this load on wave conditions, the ice concentration, and the cylinder size is investigated. These loads are compared with the pure wave loads. It is found that under the conditions studied, the mean values of the ice loads are much lower than the corresponding wave loads, even though the peak loads are substantial. Also significant is the frequency content of the ice loads. It appears that all significant frequencies are integral multiples of the wave frequency. Since the dynamics of offshore structures is dependent on the frequency of the loading pattern, these findings are worthy of further study. Particularly, laboratory tests are strongly desirable to verify these computational results.
Year: 2012