The sliding velocity over a sinusoidal bed at high water pressure
Abstract Under idealized conditions, when pressurized water has access to all low-pressure areas at the glacier bed, a sliding instability exists at a critical pressure, p c , well below the overburden pressure, p 0 . The critical pressure is given by , where l is the wave length and a is the amplit...
Published in: | Journal of Glaciology |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
1998
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0022143000002707 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002707 |
id |
crcambridgeupr:10.1017/s0022143000002707 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0022143000002707 2024-03-03T08:45:58+00:00 The sliding velocity over a sinusoidal bed at high water pressure Truffer, Martin Iken, Almut 1998 http://dx.doi.org/10.1017/s0022143000002707 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002707 en eng Cambridge University Press (CUP) Journal of Glaciology volume 44, issue 147, page 379-382 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1998 crcambridgeupr https://doi.org/10.1017/s0022143000002707 2024-02-08T08:37:11Z Abstract Under idealized conditions, when pressurized water has access to all low-pressure areas at the glacier bed, a sliding instability exists at a critical pressure, p c , well below the overburden pressure, p 0 . The critical pressure is given by , where l is the wave length and a is the amplitude of a sinusoidal bedrock, and T is the basal shear stress. When the subglacial water pressure, p w , approaches this critical value, the area of ice-bed contact, △l, becomes very small and the pressure on the contact area becomes very large. This pressure is calculated from a force balance and the corresponding rate of compression is obtained using Glen’s flow law for ice. On the assumption that compression in the vicinity of the contact area occurs over a distance of the order of the size of this area, Δl, a deformational velocity is estimated. The resultant sliding velocity shows the expected instability at the critical water pressure. The dependency on other parameters, such as wavelength l and roughness a/l, was found to be the same as for sliding without bed separation. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 44 147 379 382 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Truffer, Martin Iken, Almut The sliding velocity over a sinusoidal bed at high water pressure |
topic_facet |
Earth-Surface Processes |
description |
Abstract Under idealized conditions, when pressurized water has access to all low-pressure areas at the glacier bed, a sliding instability exists at a critical pressure, p c , well below the overburden pressure, p 0 . The critical pressure is given by , where l is the wave length and a is the amplitude of a sinusoidal bedrock, and T is the basal shear stress. When the subglacial water pressure, p w , approaches this critical value, the area of ice-bed contact, △l, becomes very small and the pressure on the contact area becomes very large. This pressure is calculated from a force balance and the corresponding rate of compression is obtained using Glen’s flow law for ice. On the assumption that compression in the vicinity of the contact area occurs over a distance of the order of the size of this area, Δl, a deformational velocity is estimated. The resultant sliding velocity shows the expected instability at the critical water pressure. The dependency on other parameters, such as wavelength l and roughness a/l, was found to be the same as for sliding without bed separation. |
format |
Article in Journal/Newspaper |
author |
Truffer, Martin Iken, Almut |
author_facet |
Truffer, Martin Iken, Almut |
author_sort |
Truffer, Martin |
title |
The sliding velocity over a sinusoidal bed at high water pressure |
title_short |
The sliding velocity over a sinusoidal bed at high water pressure |
title_full |
The sliding velocity over a sinusoidal bed at high water pressure |
title_fullStr |
The sliding velocity over a sinusoidal bed at high water pressure |
title_full_unstemmed |
The sliding velocity over a sinusoidal bed at high water pressure |
title_sort |
sliding velocity over a sinusoidal bed at high water pressure |
publisher |
Cambridge University Press (CUP) |
publishDate |
1998 |
url |
http://dx.doi.org/10.1017/s0022143000002707 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002707 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 44, issue 147, page 379-382 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000002707 |
container_title |
Journal of Glaciology |
container_volume |
44 |
container_issue |
147 |
container_start_page |
379 |
op_container_end_page |
382 |
_version_ |
1792501695065882624 |