Local Friction Laws for Glaciers: A Critical Review and New Openings
Abstract “Sliding velocity” and “friction law” are precisely defined. Different scales for tackling glacier dynamics are introduced. The energy balance in the melting-refreezing process is clarified. The validity of a Glen body as a model for ice rheology is discussed. The assumed model for subglaci...
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Cambridge University Press (CUP)
1979
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Online Access: | http://dx.doi.org/10.1017/s0022143000029750 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000029750 |
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crcambridgeupr:10.1017/s0022143000029750 2024-09-15T18:15:39+00:00 Local Friction Laws for Glaciers: A Critical Review and New Openings Lliboutry, L. 1979 http://dx.doi.org/10.1017/s0022143000029750 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000029750 en eng Cambridge University Press (CUP) Journal of Glaciology volume 23, issue 89, page 67-95 ISSN 0022-1430 1727-5652 journal-article 1979 crcambridgeupr https://doi.org/10.1017/s0022143000029750 2024-07-17T04:04:24Z Abstract “Sliding velocity” and “friction law” are precisely defined. Different scales for tackling glacier dynamics are introduced. The energy balance in the melting-refreezing process is clarified. The validity of a Glen body as a model for ice rheology is discussed. The assumed model for subglacial water is a very slightly pervious ice, and a not absolutely watertight ice-bedrock interface, owing to glacial striae and rock joints. Then autonomous hydraulic regimes and cavities at water vapour pressure have a negligible influence on the drag, and only the interconnected regime has to be considered. A more rigorous treatment of Weertman’s model (independent knobs) gives quite different numerical factors. In general a term increasing with Terzaghi’s effective pressure N has to be added to the drag. The double-valued friction law found by Weertman is shown to have been an error. Kamb’s relations for the model with a vanishing microrelief are considerably simplified. His conjectural solution cannot be extended to slopes actually found in the microrelief. The author’s (Lliboutry, 1968) treatment is unsatisfactory and includes an error. With a model consisting of irregular bumps of similar length, a new friction law is given. The pertinent measure of the bedrock roughness is then the shadowing function, not the spectral power density. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 23 89 67 95 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract “Sliding velocity” and “friction law” are precisely defined. Different scales for tackling glacier dynamics are introduced. The energy balance in the melting-refreezing process is clarified. The validity of a Glen body as a model for ice rheology is discussed. The assumed model for subglacial water is a very slightly pervious ice, and a not absolutely watertight ice-bedrock interface, owing to glacial striae and rock joints. Then autonomous hydraulic regimes and cavities at water vapour pressure have a negligible influence on the drag, and only the interconnected regime has to be considered. A more rigorous treatment of Weertman’s model (independent knobs) gives quite different numerical factors. In general a term increasing with Terzaghi’s effective pressure N has to be added to the drag. The double-valued friction law found by Weertman is shown to have been an error. Kamb’s relations for the model with a vanishing microrelief are considerably simplified. His conjectural solution cannot be extended to slopes actually found in the microrelief. The author’s (Lliboutry, 1968) treatment is unsatisfactory and includes an error. With a model consisting of irregular bumps of similar length, a new friction law is given. The pertinent measure of the bedrock roughness is then the shadowing function, not the spectral power density. |
format |
Article in Journal/Newspaper |
author |
Lliboutry, L. |
spellingShingle |
Lliboutry, L. Local Friction Laws for Glaciers: A Critical Review and New Openings |
author_facet |
Lliboutry, L. |
author_sort |
Lliboutry, L. |
title |
Local Friction Laws for Glaciers: A Critical Review and New Openings |
title_short |
Local Friction Laws for Glaciers: A Critical Review and New Openings |
title_full |
Local Friction Laws for Glaciers: A Critical Review and New Openings |
title_fullStr |
Local Friction Laws for Glaciers: A Critical Review and New Openings |
title_full_unstemmed |
Local Friction Laws for Glaciers: A Critical Review and New Openings |
title_sort |
local friction laws for glaciers: a critical review and new openings |
publisher |
Cambridge University Press (CUP) |
publishDate |
1979 |
url |
http://dx.doi.org/10.1017/s0022143000029750 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000029750 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 23, issue 89, page 67-95 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000029750 |
container_title |
Journal of Glaciology |
container_volume |
23 |
container_issue |
89 |
container_start_page |
67 |
op_container_end_page |
95 |
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1810453561756090368 |