Collapse of floating ice covers under vertical loads: test data vs. theory

Various criteria have been advanced to describe and predict the conditions under which a load will break through a floating ice cover. As a rule, the experimental basis for each of these criteria has been limited, and a comprehensive performance evaluation has yet to be carried out. Criteria based on stress, strain, deflection and strain energy are discussed first, in conjunction with the viscoelastic nature of ice and the mode of failure of an ice sheet. Five data sets are then described and utilized to test and compare the performance of failure criteria that have been proposed in the literature. Stress-based criteria, though simple to use, are only useful for very brief loading because they do not account for loading time and history. Strain- and deflection-based criteria are also subject to time and history effects that similarly limit their applicability to short-term loads. On the other hand, strain-energy criteria are found to apply equally well to short- and long-term loads of different histories. This feature is attributed to implicit consideration of time and load-history effects through integration of the deflection–load variation. Safety implications and future research avenues are discussed.