Coupling an XFEM code for linear elastic fracture propagation to a viscous flow model. GeoComputation 2019

• Main Authors: Martin Forbes, Christina Hulbe
• Format: Conference Object
• Language: unknown
• Published: 2019
• Subjects: Geospatial Information Systems; ice shelf; rifts; XFEM; mechanics; Antarctica; Antarctic; Griffith; The Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Iceberg*
• Online Access: https://doi.org/10.17608/k6.auckland.9869561.v2; https://figshare.com/articles/conference_contribution/Coupling_an_XFEM_code_for_linear_elastic_fracture_propagation_to_a_viscous_flow_model/9869561

Introduction: Ice shelves, floating extensions of grounded ice sheets and glaciers, border much of the Antarctic coastline and are responsible for most of the continent's ice mass loss. This is accomplished by melting and by iceberg calving, each process accounting for about half the total. Calving occurs as numerous smaller icebergs and by a small number of large tabular icebergs. Tabular icebergs separate from ice shelves at long, through-cutting rifts that form transverse to ice flow near the seaward fronts of the shelves. The formation and propagation of rifts transpires over time scales from days to decades, making observational studies rare. Thus, while ice shelf rifts represent a critical component in understanding and making projections of future Antarctic mass-balance, they are not well understood or represented in models. In this work we seek to adapt current day best practices in fracture propagation modelling to the Ice Sheet System Model (ISSM), therefore provide a diagnostic and predictive numerical tool for the study of ice shelf rifts. Fracture mechanics of ice shelves: Fractures are difficult to model because they introduce complex stress fields at their tips and because they may evolve and modify the geometry of the material in which they exist. The extended finite element method (XFEM) minimizes both these difficulties by the introduction of additional sets of degrees of freedom to a classical elastic finite element method. In the XFEM, fractures can be implicitly incorporated into a continuum with a heavy-side function added to all the nodes of the elements intercut by the fracture, avoiding re-meshing at every evolution of the fracture. Asymptotic displacement functions are also used to enrich the nodes in the vicinity of the crack tip to describe the strains that LEFM studies have shown to decay in this manner from a crack tip. In 1921, A. A. Griffith developed a theory of brittle fracture based on a balance between the strain energy at a fracture tip and the free surface energy necessary ...