Friction and Cohesion in Ice Rubble Reviewed

An argument is ventured that accumulations of ice rubble undergoing continuous shear deformation are essentially cohesionless. In terms of the Mohr-Coulomb failure criterion, therefore, they do not exhibit a cohesive intercept at zero confining pressure. The argument leads to the conclusion that a linear Mohr-Coulomb relationship may not be fully appropriate for describing the shear deformation of ice rubble in continuous shear. The term usually described as ice-rubble cohesiveness should be replaced with terms (or a term) which more accurately account(s) for freeze bonding between contacting ice pieces and ice-piece deformation (crushing and/or flexure). Reviewed in the light of this argument, published data on internal-friction angle of ice-rubble are shown to include the influences of freeze bonding and ice-piece deformation as well as mechanical interlocking and friction. A further conclusion, one directly consequent to the argument, is that reported values of ice-rubble cohesion have been inaccurately interpreted.