Author(s): Yoshio Muraki; Kiyoshi Izumi; Kouki Sasaki; Eiji L. Suenaga; Hiroshi Saeki
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Abstract: Recently, caisson type structures have been employed as offshore structures in regions of extreme cold. As the liquid, sand or gravel filling proceeds, the caisson freezes and the internal pressure rises. It has previously been verified that this pressure rise, due to an increase of volume caused by ice growth, depends strongly upon the permeability coefficient of the sea ice forming within the sands and gravels. Presented in this paper are results of an experiment on the permeability coefficient of sea ice which contains sands and gravels, and the analysis needed to estimate the internal pressure in a caisson structure constructed in a cold region. The following conclusions have been obtained from the investigation: 1) In the permeability coefficient experiments, experimental scatter is significant and therefore large numbers of tests are required for analysis purposes. 2) When sands and gravels are included, the sea ice is weak at points close to the surface of these particle. As the internal pressure increases, the material matrix is disrupted at these points and the coefficient of permeability increases. 3) Since the permeability coefficient increases are caused by local failure in the ice, Darcy’s Law does not apply. 4) In the experiments with sea ice containing sands and gravels, the largest particle size used showed the greatest increase in permeability coefficient with increasing internal pressure.
Year: 1988