Statistical characteristics for the strain-dependent density and the spatial position for 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) 1999
• Subjects: Earth-Surface Processes; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000001763; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000001763

Abstract Observations on the spatial distribution and on the strain dependence of the crack density are given for cracks formed during compressive, unidirectional, constant-strain-rate deformation of columnar-grain ice. Specimens, in the grain-size range of about 2 9 mm, were strained at the nominal rates of 10 −3 , 10 −4 and 10 −5 s −1 at 10°C. The axis of hexagonal crystallographic symmetry of each specimen 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 log-normal distribution function provided a good approximation to the strain dependence of the crack density. Statistical characteristics of the distribution had a maximum in the same range of strain rate as found for the strength of columnar-grain ice. Analysis of the spatial distribution of the cracks indicated some deviation from randomness for specimens of grain-size less than 5 mm and total strain less than 50 × 10 −4 . The observations provide further evidence that crack formation under the experimental conditions is a random process.