A numerical investigation of crevasse propagation and stability of calving glaciers using nonlocal continuum damage mechanics

We investigate iceberg calving from grounded tidewater and outlet glaciers using a novel creep continuum damage model for polycrystalline ice, which is valid for low stresses or strain rates. The proposed three-dimensional model is based on a thermo-viscoelastic constitutive law for ice creep and a nonlocal damage accumulation law for tension, compression and shear loadings. The model has been validated by published experimental data and is implemented in the commercially available finite element code ABAQUS by adopting a strain-based algorithm using a Lagrangian description. The model is then used to investigate conditions that enable surface crevasse propagation resulting from different boundary conditions applied to an idealized rectangular slab of ice in contact with the ocean. The basal boundary condition of the ice slab is varied from free slip to fixed (no slip) to study its effect on surface crack (crevasse) growth. The depth varying ice flow velocities lead to tensile stresses in the top region of the ice slab that leads to surface crevasse propagation. The simulation results suggest that if the ice slab is thick enough and the water depth small enough, surface crevasses will penetrate the entire ice thickness. On the other hand, if the ice slab is thin and water depth sufficiently large, crevasses will not penetrate the ice thickness.