Abstract

Elastic and viscous constants characterizing viscoelastic rheology of sea ice samples harvested in the Van Mijen Fjord of Spitsbergen were determined from a set of laboratory and field-based tests with ice cores and ice beams (2020-2022). A model of transversely isotropic continuum with vertical axis of symmetry was chosen to describe properties of columnar ice. The elastic constants were calculated from the measurements of natural frequencies of vertically and horizontally oriented ice beams and measurements of pressure wave speeds in 3 spatial directions. Dependencies of the shear wave speeds and Rayleigh wave speeds from the direction of wave propagation are discussed. Viscous constants of the Burgers model were determined from the laboratory tests on stress relaxation and loading-unloading tests performed with ice cores at different temperatures. The Burgers model was used for the simulation of ice deformations and ice stresses measured in full-scale experiments on long-term loading of floating sea ice in the Van Mijen Fjord. The ice was loaded by the bandwagon with weight 4.5 t during 2 h in 2021 and 30 h in 2022. Numerical simulations were performed with Comsol Multiphysics FE software. Simulations results describe well measured dependencies of ice stresses and displacements from the time. At the same time, it was discovered that ice temperature changes caused by weather conditions influence ice pressure significantly over the measurement time. The Burgers model was also used for the calculation of surface wave damping in ice covered ocean regions. In combination with energy dissipation in under-ice boundary layer the model describe well wave damping in a wide frequency range. Laboratory experiments in HSVA ice tank and field measurements in the Ice Fjord of Spitsbergen were used to validate the model of wave damping.