Sliding with Cavity Formation
Abstract We present a model for the determination of a sliding law in the presence of subglacial cavitation. This law determines the basal stress at a clean ice‒bedrock interface in terms of the velocity and effective pressure. The method is based on an exact solution of the Nye—Kamb (linearly visco...
Published in: | Journal of Glaciology |
---|---|
Main Author: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
1987
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0022143000008820 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008820 |
id |
crcambridgeupr:10.1017/s0022143000008820 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0022143000008820 2024-09-15T18:15:39+00:00 Sliding with Cavity Formation Fowler, A. C. 1987 http://dx.doi.org/10.1017/s0022143000008820 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008820 en eng Cambridge University Press (CUP) Journal of Glaciology volume 33, issue 115, page 255-267 ISSN 0022-1430 1727-5652 journal-article 1987 crcambridgeupr https://doi.org/10.1017/s0022143000008820 2024-07-17T04:04:04Z Abstract We present a model for the determination of a sliding law in the presence of subglacial cavitation. This law determines the basal stress at a clean ice‒bedrock interface in terms of the velocity and effective pressure. The method is based on an exact solution of the Nye—Kamb (linearly viscous) sliding problem with cavities, and uses ideas of Lliboutry (1979) to construct, via renormalization methods, an approximate law for general bedrock form. We show that, for a bedrock whose spectrum has a power‒law behaviour, one obtains a sliding law which gives the basal shear stress proportional to a power of the velocity, and to a power of the effective pressure. The effect of subglacial cavitation on the drainage system is examined, using recent ideas of Kamb. For sufficiently high velocities, drainage through a Röthlisberger tunnel system is unstable, and drainage takes place through the linked system of cavities. This leads to a reduction of the effective pressure, and by taking account of this, one can rewrite the sliding law in terms of stress and velocity only. This sliding law can be multi‒valued, and it is suggested that this underlies the dynamic phenomenon of surges. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 33 115 255 267 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract We present a model for the determination of a sliding law in the presence of subglacial cavitation. This law determines the basal stress at a clean ice‒bedrock interface in terms of the velocity and effective pressure. The method is based on an exact solution of the Nye—Kamb (linearly viscous) sliding problem with cavities, and uses ideas of Lliboutry (1979) to construct, via renormalization methods, an approximate law for general bedrock form. We show that, for a bedrock whose spectrum has a power‒law behaviour, one obtains a sliding law which gives the basal shear stress proportional to a power of the velocity, and to a power of the effective pressure. The effect of subglacial cavitation on the drainage system is examined, using recent ideas of Kamb. For sufficiently high velocities, drainage through a Röthlisberger tunnel system is unstable, and drainage takes place through the linked system of cavities. This leads to a reduction of the effective pressure, and by taking account of this, one can rewrite the sliding law in terms of stress and velocity only. This sliding law can be multi‒valued, and it is suggested that this underlies the dynamic phenomenon of surges. |
format |
Article in Journal/Newspaper |
author |
Fowler, A. C. |
spellingShingle |
Fowler, A. C. Sliding with Cavity Formation |
author_facet |
Fowler, A. C. |
author_sort |
Fowler, A. C. |
title |
Sliding with Cavity Formation |
title_short |
Sliding with Cavity Formation |
title_full |
Sliding with Cavity Formation |
title_fullStr |
Sliding with Cavity Formation |
title_full_unstemmed |
Sliding with Cavity Formation |
title_sort |
sliding with cavity formation |
publisher |
Cambridge University Press (CUP) |
publishDate |
1987 |
url |
http://dx.doi.org/10.1017/s0022143000008820 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008820 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 33, issue 115, page 255-267 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000008820 |
container_title |
Journal of Glaciology |
container_volume |
33 |
container_issue |
115 |
container_start_page |
255 |
op_container_end_page |
267 |
_version_ |
1810453558664888320 |