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Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

Published online by Cambridge University Press:  07 February 2018

R. Frederking
R. Frederking*
Affiliation:
Division of Building Research, National Research Council of Canada, Ottawa, Ontario KIA oR6, Canada
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Abstract

An ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is atmost 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar-grained ice, when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

Type
Abstracts of Papers Presented at the Symposium but not Published in Full in this Volume
Information
Journal of Glaciology , Volume 19 , Issue 81 , 1977 , pp. 657 - 658
Copyright
Copyright © International Glaciological Society 1977

This paper is published in full in Journal of Glaciology, Vol. 18, No. 80.

Discussion

P. R. Kry: Do you think a lubricant such as silicone oil would reduce friction on the side restraining plates?

R. Frederking: Kerosene and some other light oils reduced the friction. We did not test silicone oil.

A. J. Gow: You mentioned that you used columnar ice with horizontal c-axes. Did you attempt to manufacture ice samples with c-axes vertical? In our studies of lake ice in New Hampshire we found that the c-axis vertical structure is much more common than the c-axis horizontal structure.

Frederking: No, we could grow ice with horizontal c-axes in the laboratory but could not make reproducible samples with vertical c-axes.

J. W. Glen: In your graph for granular-snow ice the curves for uniaxial and confined strengths crossed, implying that in some range confined strength is less than unconfined. Do you believe this represents a real situation? Surely unconfined strength must always be lower.

Frederking: This is an artefact of our least-squares fitting method. It may be significant that the curves approach each other at the low strain-rates.