Nonsimultaneous crushing during edge indentation of freshwater ice sheets

Abstract

Indentation tests were conducted by pushing segmented indentors into the edge of freshwater ice sheets at different velocities. Ice crushing forces were measured independently in each segment. Results of these tests indicate that there is simultaneous generation of forces on all segments during low-velocity indentation, whereas there is a nonsimultaneous force acting on the segments during high-velocity indentation. For brittle crushing of ice at a high indentation rate, the effective pressures measured during these tests are in the range of pressures measured in the field during the impact of ice floes against large structures. Under the assumption that the size of crushing zones becomes small with increasing indentation speed, a statistical model is used to determine the correlation between the forces measured in different segments in terms of a correlation length parameter. A comparison of the trends in the plots of experimental data with theoretical results shows that the correlation length parameter decreases as the reciprocal of the indentation velocity. Under the assumption of the similarity principle, according to replica modeling, an estimate of the correlation length parameter is empirically obtained in terms of ice thickness and indentation velocity.