4 - Fixed Structures and Medium-Scale Indentation Tests

Summary

Measurements of pressure on fixed structures are reviewed including the Helsinki and JOIA test programmes. The Molikpaq experience and the Hans Island programmes are described in some detail. Loads tend to be concentrated in small areas, as was the case for ship structures (the high-pressure zones). Size effect of ice pressure with regard to ice thickness is discussed; average pressures decrease with ice thickness. The medium scale field indentation programmes are described, covering the Pond Inlet, Rae Point, and Hobsons Choice Ice Island test series. Ice-induced vibrations are introduced; these were observed in the Molikpaq structure and in many indentation tests. The vibrations tended to occur at certain speed ranges, associated with ice crushing. Results of field tests on iceberg failure are also reviewed, in which supporting evidence for layer failure was obtained.