The freeze-bond strength in first-year ice ridges. Small-scale field and laboratory experiments

摘要

The strength of freeze-bonds in-between blocks in first-year ridges has been investigated through field and laboratory tests. A series of small scale field tests with submerged ice blocks were carried out in Adventfjorden on Svalbard in March-April 2005. An opening was made in the landfast level ice and the ice was sawed into cubes with dimensions of 0.24 m. Some of the cubes were cut in two parts and then frozen together to simulate freeze bonds between the ice blocks. The other blocks were submerged without forming adfreeze bonds. In addition to that, laboratory tests with both laboratory made layered (fresh- and seawater) and sea ice were conducted in February-April 2006 at UNIS. The strength of the freeze bonds, the strength of the submerged ice blocks and their changes with time of submerging, confining pressure, block size and physical properties of ice were investigated. The average strength of freeze bonds was found to be 0.032±0.018 MPa after 48 h of being submerged in the field. The corresponding values from the laboratory tests were 0.067 ± 0.052 MPa for the sea ice testing and 0.274 ± 0.142 MPa for the laboratory made layered freshwater ice up to 60 h of being submerged. The initial physical properties of ice, the confining pressure applied to the ice pieces before and during submerging together with the size of the ice blocks are the main parameters that affect the freeze bond strength.