Damage and microstructural change in laboratory grown ice under high pressure zone conditions

Melanson, Paul M. (1998) Damage and microstructural change in laboratory grown ice under high pressure zone conditions. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (20MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Ice-structure interactions, where crushing is the predominant mode of failure, are characterised by zones of intense high pressure within the ice feature. This work investigates the mechanical and microstructural behaviour within these zones by using triaxial testing on laboratory grown freshwater granular ice. The latest interpretation of the behaviour of ice in high pressure zones during ice-structure interactions is presented, based on previous work at Memorial University of Newfoundland. A review of triaxial testing on ice is also presented. -- Results of triaxial testing on ice indicate the existence of two separate but overlapping deformation mechanism regimes at high and low confining pressures. High microcrack densities followed by a reduction in grain size by recrystallisation and restructuring were observed in low hydrostatic pressure tests (p < 30 MPa). At higher pressures (p > 40 MPa) this was replaced by more intense recrystallisation and possible pressure melting at grain boundaries and triple points. -- Triaxial tests were used in the calibration of a pressure-dependent constitutive model for granular ice. The constitutive model is based on continuum damage mechanics and uses the reduction of the standard Burgers body to a single non-linear dashpot to model the response of ice under high stress and high strain conditions. Results show moderate agreement with test data collected from ice damaged triaxially at constant deformation rate and loaded axially at high confining pressures,. More work is needed to improve the calibration of the model further over a wider range of confining pressures.

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