| Popis: |
Ice loss from glaciers and ice sheets is the largest contributor to sea level rise. Damaged ice is central to the stability of the Antarctic Ice Sheet and calving of tabular icebergs from ice shelves accounts for more than half of all the ice lost from Antarctica each year. The processes driving calving and fracture are complex but not yet well understood. The aim of this talk is to present a physically based modelling of fracture. The timing of calving is currently difficult to predict and is only included in some ice sheet models. Calving and cliff retreat rates are based on heuristic arguments or limited observations scaled up to the whole of Antarctica. There is no guarantee that current methods accurately capture the sea level contributions and physically based modelling is needed. Recently, phase field models for fracture have gained a large following due to their ability to predict complex cracking phenomena such as crack branching and coalescence, or crack nucleation and have been applied to ice sheets for example by Clayton et al. (2022). We employ a phase field formulation of fracture for Maxwell viscoelastic materials capable of capturing the creep of glacial ice over longer periods as well as instantaneous elastic deformation. In this talk we present different failure criteria and fracture driving forces used in phase field modelling and their impact on cliff retreat rates. We draw parallels with existing models and commonly used failure criteria and expand on the possibilities of using phase field modelling in large scale domains. Clayton, T., Duddu, R., Siegert, M., Martínez-Pañeda, E. (2022). A stress-based poro-damage phase field model for hydrofracturing of creeping glaciers and ice shelves. Engineering Fracture Mechanics, 272, 108693. |
