Experimental observations of the brittle failure process of ice and ice-structure contact

Abstract

Laboratory experiments, where a block of freshwater ice was crushed in a continuous manner against a compliant structure, are described. The observed brittle failure process of ice can be characterised as crushing with flaking. The failure process, the ice-structure contact, and the ice load were affected by the clearance between a test structure and a confinement box for ice. When this clearance, or gap height, was large, the top of an ice block was wedge shaped and a contact line was observed. This contact type is in agreement with observations made during earlier small scale experiments. When the gap height was small the contact was wider, but a contact line was also observed in this case. On both sides of this there was a hard layer of crushed ice. This contact type resembles those observed in tests with large contact areas. Thin sections of ice showed that, irrespective of gap height, the solid ice had a direct contact with the structure. The failure mode and contact type were independent, but the ice load was dependent, of ice type (S1 or S2), grain orientation, or loading velocity.