Scale-model ridges and interaction with narrow structures, Part 3 Analysis of Ridge Keel Punch Tests:POAC 2021

• Main Author: Heinonen, Jaakko
• Format: Other Non-Article Part of Journal/Newspaper
• Language: English
• Published: POAC 2021
• Subjects: ice load; ridge loads; punch tests; offshore wind turbine; ice rubble; ridge keel; Platen; Arctic; Sea ice
• Online Access: https://cris.vtt.fi/en/publications/7378cab4-1e84-43cd-8262-2ff30a330a49; https://poac.com/Proceedings/2021/POAC21-091.pdf

An experimental campaign to investigate sea ice ridge interaction with bottom-fixed structures was carried out in the Aalto ice tank in Espoo Finland in August, 2019. The aim was to investigate a) the scaled ridge properties, b) the ice processes during testing and c) the scaling of ridge forces with respect to a cylindrical and a conical structure at the water line. This presentation focuses on analyzing ridge keel punch tests. In a punch test, a circular platen of consolidated layer is first cut free from the surrounding ice field. Thereafter, the ice is pushed vertically downwards with a cylindrical indentor to break the underlying keel. The measured load-displacement relationship can be used for the evaluation of the mechanical properties of rubble. Three ice sheets were created and used to build ridges, in which the ridge consolidation temperature and time were varied. All together 24 punch tests were carried out, whereas 14 of them were done for consolidated ridge, six for unconsolidated ridge, three for surrounding level ice and one in the open water to determine the buoyancy load on the indentor. Both the structural tests and punch tests showed clearly that the ridge strength and load depend strongly on the consolidation.