Author(s): K. R. Croasdale; R. W. Marcellus
Linked Author(s):
Keywords: No Keywords
Abstract: Offshore platforms are being considered for the production of hydrocarbons from the nearshore areas of the Arctic Ocean. These platforms will be very large in order to accommodate production facilities and possibly an offshore terminal. They will need to be designed to withstand the most extreme ice features expected during their 25-30 year lifespan. Ice forces will be governed either by local ice failure or by available driving forces. Because of the large size of the production platforms and the extreme ice thicknesses expected, the available driving mechanisms may limit the ice forces. This paper reviews driving mechanisms in relation to ice forces, and describes a method of predicting ice forces on large marine structures. In particular, the paper examines the various stages of interaction during a collision between a large ice feature and a structure. In the initial stage of interaction, the forces are dominated by the dissipation of the kinetic energy of the large ice feature as it is brought to rest. For an island-type structure, the kinetic energy of thick ice features can be dissipated by deformation and scouring of the underwater slopes. The paper presents an ice/soil interaction model which is being used to quantify these interactions. Once the large ice feature has been brought to rest the driving mechanism is made up of wind and current drag plus die pack ice pressure. The paper examines these steady driving forces and suggests that ridge-building in the surrounding pack ice will Limit the maximum steady forces on the structure.
Year: 1981