An analytical model and laboratory tests on iceberg sediment interaction

Icebergs of the Northwest Atlantic originate for the most part from glaciers of Western Greenland. After calving, these bergs drift north, then west and are finally picked up by the south-flowing Labrador current. Many icebergs drift ashore during their passage to the Grand Banks, finally melting in the Gulf Stream. These drifting masses of ice, many of which are in excess of one million tons, (equivalent to a block 150 ft. wide, 600 ft. long, 100 ft. above water and 400 ft. draft) present two main areas of concern to the offshore drilling operators: (a) the possibility of a direct collision of the moving iceberg with a drilling rig or fixed structure, thus requiring knowledge of the iceberg movement and behaviour to enable avoidance action to be taken. (b) damage to installations near the water sediment interface through scouring from bottom dragging icebergs thus requiring a knowledge of the interaction of the iceberg and sea floor sediment and the sediment strength characteristics. To try to answer these problems, icebergs have formed a major part of the Ocean Engineering Research Program at Memorial University of Newfoundland over the past four years. Many aspects such as stability, and grounding have towing, drift shape been considered. This paper describes a laboratory phase of the iceberg grounding studies currently in progress.