EXPERIMENTAL-OBSERVATIONS OF THE BRITTLE FAILURE PROCESS OF ICE AND ICE STRUCTURE CONTACT

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 crush ing with flaking. The failure process, the ice-structure contact, and the ice load were affected by the clearance between a test structure a nd 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 du ring earlier small scale experiments. When the gap height was small th e 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 co ntact type resembles those observed in tests with large contact areas. Thin sections of ice showed that, irrespective of gap height, the sol id ice had a direct contact with the structure. The failure mode and c ontact type were independent, but the ice load was dependent, of ice t ype (S1 or S2), grain orientation, or loading velocity.