Author(s): Richard Mckenna; Greg Crocker
Keywords: Sea Ice; Ice Mechanics and Properties
Abstract: A significant contributor to iceberg deterioration is wave erosion at the waterline and the subsequent detachment of overhanging slabs of ice – a process known as calving. The time scale of the calving process is in the order of hours to days depending on water temperature and sea state. Present iceberg forecasting models rely on calving rates based on an elastic solution balancing the weight of the overhanging slab and the resistance to failure at the base of the slab. Key parameters include the radius of the iceberg, the thickness and extent of the overhang, and the ice failure stress. In this paper, we consider viscoelastic contributions to ice deformation during the calving process for some typical waterline shapes and iceberg surface temperature profiles. Isotropic three-dimensional ice behaviour is considered through limiting plane stress and plane strain conditions for vertical profiles, and the solution is implemented in a finite model. Elastic, delayed elastic and steady creep terms, which are significant at these time scales, have been considered. Viscoelastic effects are shown to reduce stresses at the base of the overhang when compared to those calculated using an elastic solution.