Scale-model ice ridges and interaction with narrow structures, Part 4: Global loads and failure mechanisms

An experimental campaign was carried out in the Aalto ice basin to investigate sea ice ridge interaction with bottom-fixed structures. The campaign covered three different ice sheets and ridges. Punch tests, flexural strength test and compressive strength test were carried out on the model ice. Two different structures were tested, one with cylindrical and one with conical waterline (cone angle 75°). A geometric scale-factor of 15 was applied between the model and prototype. The model was pulled through the ridges while measuring the loads. A monitoring system with six cameras was installed to observe the deformation pattern of ice. Two of these cameras were installed above the sea surface and four of them were installed underwater. The failure mode of ridge keel was observed by using underwater cameras, and observations showed that the breaking of keel had a shrinkage-expansion pattern before all freeze bond in front of the structure was broken by the structure. For the consolidated ridge, the cone part of the structure could reduce the ice loads induced by the consolidated layer, but the cone did not effectively influence the loads induced by rubble due to its short length. For the unconsolidated ridge, the cone could reduce the ice loads due to weak confinement of the contacting rubble near water line.