Statistical characteristics for the type and length of deformation-induced cracks in columnar-grain ice

• Published in: Journal of Glaciology
• Main Author: Gold, Lorne W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1997
• Subjects: Earth-Surface Processes; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000003269; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000003269

Abstract Observations are reported on cracks formed during compressive, unidirectional, constant-strain-rate deformation of columnar-grain ice. The axis of hexagonal crystallographic symmetry of each grain tended to be in the plane perpendicular to the long direction of the grains and to have a random orientation in that plane. For stress applied perpendicular to the long direction of the grains, the deformation was practically two-dimensional. It was found that the relative proportion of grain-boundary cracks increased with increasing strain rate, decreasing temperature and, for strain rate greater than 7 × 10 −5 s −1 , with decreasing grain-size. Almost all the grain-boundary cracks had at least one edge at a triple point. For each test, the grain-boundary and transcrystalline crack lengths tended to have a log-normal distribution. The logarithmic mean crack length (LMCL) decreased with increasing strain rate, decreasing grain-size and decreasing temperature and tended to a constant value of 0.75 mm at 10°C. For grain-size of 3 mm or greater, the LMCL had a maximum at a strain rate of 10 −5 to 10 −6 S −1 at −10°C. The LMCLs and the relative proportion of grain-boundary cracks tended to be normally distributed for given load conditions.