Field Measurements of Northern Baltic Pressure Ridges

摘要

The report investigates the characteristics of ice pressure ridges in the Bay ofBothnia. Pressure ridges are one of the harshest elements encountered by ice-going vessels, and the current lack of information on their properties hinders understanding of the dynamics of ship-ridge interaction. Investigation of these characteristics is necessary in order to establish a link between the structure and mechanics of ice ridges, and ice loading on ships. The aim of the paper is to describe a series of field experiments and report the measurement results. Tests were conducted in the field from the research vessel RV Aranda, over a period of nine days, beginning on 10th of March 1992. The research team consisted of members from both the Helsinki and the Lulea Universities of Technology. Sets of vertical holes were drilled in a grid pattern over the ridges in order to develop cross-sectional profiles and views of the void structure. Ice samples from these sites were taken to the laboratory on board RV Aranda, and were tested for uniaxial compressive strength, salinity and density. Ice pieces were collected from the sails, and were measured along three axes. In-situ tests of ice compressive strengths were made using a pressometer.