Shear dilation of subglacial till results in time-dependent sliding laws
The dynamics of glacial sliding over water-saturated tills are poorly constrained and difficult to capture realistically in large-scale models. Experiments characterize till as a plastic material with a pressure-dependent yield stress, but the subglacial water pressure may fluctuate on annual to dai...
Main Authors: | , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
The Royal Society
2023
|
Subjects: | |
Online Access: | https://discovery.ucl.ac.uk/id/eprint/10164131/1/Hewitt_Shear%20dilation%20of%20subglacial%20till%20results%20in%20time-dependent%20sliding%20laws_VoR.pdf https://discovery.ucl.ac.uk/id/eprint/10164131/ |
id |
ftucl:oai:eprints.ucl.ac.uk.OAI2:10164131 |
---|---|
record_format |
openpolar |
spelling |
ftucl:oai:eprints.ucl.ac.uk.OAI2:10164131 2023-12-24T10:17:37+01:00 Shear dilation of subglacial till results in time-dependent sliding laws Warburton, KLP Hewitt, DR Neufeld, JA 2023-01-25 text https://discovery.ucl.ac.uk/id/eprint/10164131/1/Hewitt_Shear%20dilation%20of%20subglacial%20till%20results%20in%20time-dependent%20sliding%20laws_VoR.pdf https://discovery.ucl.ac.uk/id/eprint/10164131/ eng eng The Royal Society https://discovery.ucl.ac.uk/id/eprint/10164131/1/Hewitt_Shear%20dilation%20of%20subglacial%20till%20results%20in%20time-dependent%20sliding%20laws_VoR.pdf https://discovery.ucl.ac.uk/id/eprint/10164131/ open Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences , 479 (2269) , Article 20220536. (2023) subglacial till glacier dynamics basal sliding Article 2023 ftucl 2023-11-27T13:07:32Z The dynamics of glacial sliding over water-saturated tills are poorly constrained and difficult to capture realistically in large-scale models. Experiments characterize till as a plastic material with a pressure-dependent yield stress, but the subglacial water pressure may fluctuate on annual to daily timescales, leading to transient adjustment of the till. We construct a continuum two-phase model of coupled fluid and solid deformation, describing the movement of water through the pore space of a till that is itself dilating and deforming. By forcing the model with time-dependent effective pressure at the ice-till interface, we infer the resulting relationships between basal traction, solid fraction and rate of deformation. We find that shear dilation introduces internal pressure variations and transient dilatant strengthening emerges, leading to hysteretic behaviour in low-permeability materials. The result is a time-dependent effective sliding law, with permeability-dependent lag between changes in effective pressure and the slidingspeed. This deviation from traditional steady-state sliding laws may play an important role in a wide range of transient ice-sheet phenomena, from glacier surges to the tidal response of ice streams. Article in Journal/Newspaper Ice Sheet University College London: UCL Discovery |
institution |
Open Polar |
collection |
University College London: UCL Discovery |
op_collection_id |
ftucl |
language |
English |
topic |
subglacial till glacier dynamics basal sliding |
spellingShingle |
subglacial till glacier dynamics basal sliding Warburton, KLP Hewitt, DR Neufeld, JA Shear dilation of subglacial till results in time-dependent sliding laws |
topic_facet |
subglacial till glacier dynamics basal sliding |
description |
The dynamics of glacial sliding over water-saturated tills are poorly constrained and difficult to capture realistically in large-scale models. Experiments characterize till as a plastic material with a pressure-dependent yield stress, but the subglacial water pressure may fluctuate on annual to daily timescales, leading to transient adjustment of the till. We construct a continuum two-phase model of coupled fluid and solid deformation, describing the movement of water through the pore space of a till that is itself dilating and deforming. By forcing the model with time-dependent effective pressure at the ice-till interface, we infer the resulting relationships between basal traction, solid fraction and rate of deformation. We find that shear dilation introduces internal pressure variations and transient dilatant strengthening emerges, leading to hysteretic behaviour in low-permeability materials. The result is a time-dependent effective sliding law, with permeability-dependent lag between changes in effective pressure and the slidingspeed. This deviation from traditional steady-state sliding laws may play an important role in a wide range of transient ice-sheet phenomena, from glacier surges to the tidal response of ice streams. |
format |
Article in Journal/Newspaper |
author |
Warburton, KLP Hewitt, DR Neufeld, JA |
author_facet |
Warburton, KLP Hewitt, DR Neufeld, JA |
author_sort |
Warburton, KLP |
title |
Shear dilation of subglacial till results in time-dependent sliding laws |
title_short |
Shear dilation of subglacial till results in time-dependent sliding laws |
title_full |
Shear dilation of subglacial till results in time-dependent sliding laws |
title_fullStr |
Shear dilation of subglacial till results in time-dependent sliding laws |
title_full_unstemmed |
Shear dilation of subglacial till results in time-dependent sliding laws |
title_sort |
shear dilation of subglacial till results in time-dependent sliding laws |
publisher |
The Royal Society |
publishDate |
2023 |
url |
https://discovery.ucl.ac.uk/id/eprint/10164131/1/Hewitt_Shear%20dilation%20of%20subglacial%20till%20results%20in%20time-dependent%20sliding%20laws_VoR.pdf https://discovery.ucl.ac.uk/id/eprint/10164131/ |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences , 479 (2269) , Article 20220536. (2023) |
op_relation |
https://discovery.ucl.ac.uk/id/eprint/10164131/1/Hewitt_Shear%20dilation%20of%20subglacial%20till%20results%20in%20time-dependent%20sliding%20laws_VoR.pdf https://discovery.ucl.ac.uk/id/eprint/10164131/ |
op_rights |
open |
_version_ |
1786205872191438848 |