Some influences of ice rubble field formations around artificial islands in deep water

Abstract

This paper presents some results of recent design studies on the effect of the ice environment on Artificial Production Islands in deep water in the Canadian Beaufort Sea. The ice climate at the 30-m water depth considered for this study is seaward of the landfast ice, so that large ice movements from varying directions can be expected, although the direction of the Beaufort Gyral will dominate. A rubble field formed on the exposed face of the island will be partially free-floating at its furthest extent, but will be fully grounded and highly consolidated in the first few meters of water depth. Freezing of the voids between blocks of ice in the rubble determines the overall shear strength of the rubble and how much will be swept away in a subsequent ice movement from a different direction. The influence of the formation and structure of the rubble field on forces and sliding resistance of a deep-water artificial island are studied. Evidence is presented showing the formation of such rubble fields in the shear zone. An example demonstrates the effect of various ice-rubble field parameters on the safety of an island.