The Relationship between the Visco-Elastic and Structural Properties of Fine-Grained Snow
New and felt-like snow was sieved and sintered at a constant temperature in order to produce homogeneous samples of fine, rounded-grain snow with a density in the range 270–340 kg m −3 . The structure of single samples was changed in stages by non-destructive uniaxial compression. This deformation,...
| Published in: | Journal of Glaciology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Cambridge University Press (CUP)
1975
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0022143000021985 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000021985 |
| Summary: | New and felt-like snow was sieved and sintered at a constant temperature in order to produce homogeneous samples of fine, rounded-grain snow with a density in the range 270–340 kg m −3 . The structure of single samples was changed in stages by non-destructive uniaxial compression. This deformation, which amounted to 30%, took place within 8 hours (thus limiting temperature metamorphism). At each stage the Young’s modulus was measured quasi-statically and the creep behaviour under constant uniaxial compression was recorded. Stereological analysis of sections from the samples provided mean values for both grain-bond and grain properties. The Young’s modulus increased with density slightly more strongly than linearly, whereas the low-stress viscosity in unconfined compression increased nearly exponentially for densities less than 380 kg m −3 . The maximum densification resulted in a 15-fold increase in the measured visco-elastic properties. However, the number of grain bonds per unit mass increased linearly by a factor in the range 1.5 to 2 while the average grain-bond size remained constant. It is concluded that only a fraction of the grain bonds in a snow sample transmit an applied stress, and that the new grain bonds formed during the deformation of a snow sample determine the visco-elastic properties of snow. The hypothesis that chains, defined as series of stress-bearing grains, are the basic units of snow structure is developed. Semi-quantitative calculations developed from the chain concept explain the observed variations in the visco-elastic properties. |
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