CREEP OF SNOW AND ICE.
Constant load creep tests in uniaxial unconfined compression were performed on samples of sintered snow and bubbly polycrystalline ice. Nominal axial stresses were in the range 0.1 to 1.0 kgf/sq cm for snow, and 0.5 to 20 kgf/sq cm for ice. The range of temperatures investigated was from -0.5 to -34...
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| Format: | Text |
| Language: | English |
| Published: |
1966
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| Online Access: | http://www.dtic.mil/docs/citations/AD0649367 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0649367 |
| Summary: | Constant load creep tests in uniaxial unconfined compression were performed on samples of sintered snow and bubbly polycrystalline ice. Nominal axial stresses were in the range 0.1 to 1.0 kgf/sq cm for snow, and 0.5 to 20 kgf/sq cm for ice. The range of temperatures investigated was from -0.5 to -34.5C. Assuming creep to follow the Arrhenius relation, values of apparent activation energy for secondary creep under a nominal axial stress of 0.5 kgf/sq cm varied from 10.7 kcal/mole for ice of density 0.83 g/cu cm to 17.8 kcal/mole for snow of density 0.44 g/cu cm. The dependence of strain rate epsilon on stress sigma for polycrystalline ice subjected to stresses in the range 0.5 to 20 kgf/sq cm at temperatures of -4 and -10C could best be described by a relation of the form epsilon = C sub 1 sigma + C sub 2 sigma to the 3.5 power where C sub 1 and C sub 2 are constants for a given ice type. It is suggested that the creep of polycrystalline ice depends on at least two distinct mechanisms in the stress range studied. If each mechanism has its own characteristic activation energy, the apparent activation energy measured in creep experiments may well vary with stress level. In snow subjected to a given nominal stress, such an effect should be reflected in variation of apparent activation energy with bulk density. (Author) |
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