Scale-model ridges and interaction with narrow structures, Part 1: Overview and scaling

An experimental campaign to investigate sea ice ridge interaction with bottom-fixed structures was carried out in the Aalto ice basin. Ice ridges were produced, their consolidation was monitored, the properties of level ice and ridges were tested. Finally, a structure was pulled through the level ice and ridges while measuring the loads and monitoring the deformation pattern. Two different structures were tested, one with cylindrical and one with a conical waterline shape. We investigated a) the scaled ridge properties, b) how structures broke level ice and ice ridge, and c) the scaling of ridge forces with respect to a cylindrical and a conical structure at the waterline. Full-scale ridge structure interaction data are available for the Norströmsgrund lighthouse, so we used its size in scaling the tests. We assumed that gravity/buoyancy forces contribute and combined Froude and Strength scaling with a geometric scale-factor of 15. The initial ice temperature and accumulated air temperatures (FDD) during consolidation were varied to investigate how reasonably scaled ridge properties can be achieved. The campaign covered three different ice sheets and ridges. Punch tests, flexural strength, compressive strength tests were carried out. The main preliminary observations are that loads from level ice on vertical structure (F Vli ) gave the highest load. Next, in decreasing order of magnitude, followed the load from a ridge on vertical structure (F Vri ), load from a ridge on sloping structure (F Sri ), and finally, the load from level ice on sloping structure (F Sli ).