Modeling Splitting and Spalling of Columnar Ice Compressed Biaxially:The Role of Crack Nucleation

Columnar ice exhibits three failure modes under increasing lateral confinement across the columns: splitting, Coulombic shear faulting, and spalling. Modeling of the splitting-to-spalling transition under increasing confined compression is considered here. Shear faulting is not considered. A three-dimensional crack nucleation model, based on a grain boundary sliding approach, is formulated to model brittle failure mechanisms under biaxial compression along and across the columns. The growth of the nucleated crack is based on the wing crack approach. The numerical results were in good agreement with experimental data for both across-column and along-column biaxial compression. The model shows that in columnar ice, crack nucleation preceded by sliding along tapered grain boundaries induces splitting-to-spalling transition under increasing confinement.