On the role of frictional sliding in the compressive fracture of ice and granite: Terminal vs. post-terminal failure

Biaxial compressive experiments of terminal and post-terminal failure have been performed at −3 and −10 °C on columnar-grained, S2 freshwater ice proportionally loaded across the columns under moderate confinement where Coulombic faulting limits the terminal strength. The results show that the internal friction coefficient that governs terminal failure is closely similar to the coefficient of static friction across the fault. An examination of the literature reveals that granite exhibits the same relationship. When the internal friction coefficients measured here are used to evaluate the recently developed comb-crack mechanism for brittle compressive failure under low confinement, the agreement between theory and experiment is better than first found.