OVERVIEW OF THE MOLIKPAQ MULTI-YEAR ICE LOAD REANALYSIS 2007 JIP

摘要

A Joint Industry Project (JIP) has been carried out from 2007-2010 to revisit the original data of the 1985-86 Amauligak I-65 deployment of the Molikpaq in the Beaufort Sea. The JIP focused on loads from multi-year ice, and took a fresh look at the instrumentation, ice conditions and analysis methods. The Molikpaq was equipped with various ice load measurement devices including strain gauges, extensometers, and Medof panels. Each type of instrumentation had its own peculiarities. Since the Medof pressure panels were the only instrument which made direct measurement of ice loads at the interface between the ice and the structure, they had an important role in the calibration of the extensometers and strain gauges. A new assessment of Medof panel performance suggests that the panels over predicted ice forces. The strain gauges installed in the steel hull of the Molikpaq were sensitive to the height at which the load was applied. The extensometers, which measured deflection of the structure's faces, responded differently, depending on the distribution of ice loads across the structure face. A detailed review of available videos provided confirmation of failure modes and assisted in the determination of ice type and thickness. Uncertainties in instrument performance and ice thickness, as applied to average global ice pressures, are discussed. Results of this JIP suggest "Historical Case" ice loads and pressures of previous studies are about twice the level of the "Best Estimate Case" of this study. The conclusions reached in this paper are those of the authors, and permission to publish by the JIP participants does not imply that all JIP participants share the same conclusions as the authors.