Author(s): David Morgan
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Keywords: No Keywords
Abstract: Understanding the behaviours and forces associated with ice-structure interaction is important in designing structures and vessels for use in arctic and cold regions, whether they are fixed (e. g., piers, caissons, breakwaters) or floating (e. g., vessels, moored or dynamically positioned platforms). By better understanding these behaviours and forces, costs can be reduced and operating seasons can be extended thereby allowing resource development and other activities to be pursued in regions where it was previously believed to not be possible. Past work by the C-CORE Centre for Arctic Resource Development (CARD) demonstrates the potential feasibility of using three-dimensional discrete element techniques to model level ice rubbling against upward sloping cones (Morgan et al., 2015). A defining characteristic of CARD’s modelling of ice failure is that blocks of ice are not represented by a single particle; instead, they are represented by a collection of bonded particles (“composite-blocks”) which break into smaller blocks as bonds fail. These past efforts showed early promise, and more recent modelling activity presented in this work advances these efforts: particle contact model complexity has been reduced, sliding friction is better represented, tumbling of composite-blocks and individual particles is more realistic (particularly on the face of the rubble pile), and the addition of bond visualization facilitates a better understanding of the fracture process and rubble behaviour. Specifically, it is shown that the potential to achieve “circumferential” and “radial” cracks is likely as good with the linear spring-dashpot particle contact model as it is with the more complicated Hertz-Mindlin model, and that several rubble pile characteristics (e. g., ride-up height, and percentage of pile above the waterline) are influenced by particle-level rolling resistance (which controls tumbling). The paper concludes with a discussion of potential extensions and ongoing efforts, including more realistic modelling of ice strength, reduction of unrealistic attrition of multi-particle blocks of ice rubble, inclusion of ice ridges, validation of measured forces against known data.
Year: 2016