Ice rubble frictional resistance by critical state theories

To describe the ice rubble shear strength, the Mohr-Coulomb criterion is often recommended. However, its inconsistency with some shear strength measurements was reported in the literature. The paper argues that a main source of this inconsistency is the ice rubble tendency towards volumetric changes which are ignored in the Mohr-Coulomb criterion. This argument is supported by the available data on bi-axial compression of ice rubble. The influence of volumetric changes on the ice rubble shear strength can be included by the means of the critical state concept. Several models based on this concept were reviewed; one of which, the Cam clay model, showed the best consistency with the bi-axial compression data and reported friction angles (presumably close to the critical state).