Ice loads on an elastic model of the Molikpaq

Abstract

In 1986, the offshore structure Molikpaq experienced severe vibrations due to ice loading while drilling for hydrocarbons in the Canadian Beaufort Sea. These strong ice-induced vibrations were unprecedented for a wide structure in ice, and their cause is not yet fully understood. Motivated by this event and the ensuing controversy over its cause, the Canadian Hydraulics Centre has conducted a series of physical model tests to gain further insight into the loading and dynamic response of wide structures in ice. A sophisticated segmented elastic model of the Molikpaq structure was designed and built for this study. The stiffness of the model can be adjusted to simulate both stiff and soft sand cores. This paper provides information on the test program, the design of the elastic model and its behavior in a wide range of ice conditions. Results on ice loads, foundation loads, and structural deformations are presented and discussed. Finally, global ice loads from the model study are favorably compared to available information on the full scale ice loads experienced by the real Molikpaq. This result highlights the usefulness of physical model tests to determine ice loads on Arctic structures.