In situ sensing guided geotechnical modelling of subglacial deformation
Data collected by in situ subglacial probes has been used to guide a series of geotechnical tests on till. The testing provides an opportunity to develop a process-based understanding of movement patterns observed in the subglacial environment. The probes were deployed by the Glacsweb project at Ska...
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ftsouthampton:oai:eprints.soton.ac.uk:432536 2023-07-30T04:04:27+02:00 In situ sensing guided geotechnical modelling of subglacial deformation Hart, Jane 2014-12 https://eprints.soton.ac.uk/432536/ English eng Hart, Jane (2014) In situ sensing guided geotechnical modelling of subglacial deformation. American Geophysical Union, Fall Meeting 2014, , San Francisco, United States. 15 - 19 Dec 2014. Conference or Workshop Item NonPeerReviewed 2014 ftsouthampton 2023-07-09T22:30:45Z Data collected by in situ subglacial probes has been used to guide a series of geotechnical tests on till. The testing provides an opportunity to develop a process-based understanding of movement patterns observed in the subglacial environment. The probes were deployed by the Glacsweb project at Skalafellsjökull, Iceland, in 2008 and 2012. They were emplaced in till below 80 m of ice and recorded a number of variables including pore pressure, case stress, movement and conductivity. During the winter of 2008-2009 cyclic pressure changes were recorded in the till. Repeated pore pressure increases of up to 20% occurred over a variable period of one to eight weeks. Each rise was followed by a sharp drop in pore pressure lasting up to a few days. A back pressure shear box was used to replicate the pore pressure changes whilst maintaining a constant horizontal shear stress and normal total stress to examine effects on deformation and strain rate. Till was collected for testing from the ice margin close to the probes in 2012 and remoulded for use in the back pressure shear box. General characterisation of the till was performed to benchmark it against previous work and then a series of pore pressure re-inflation tests were undertaken. These approximated the pore pressure variations observed in the field by linearly increasing pore pressure and so decreasing normal effective stress. The till displayed dilatancy-induced episodic increases in strain rate. These were regulated by consolidation that increased shear strength and so reduced strain rate. Strain rate variations were similar to ice velocity variations recorded by differential GPS deployed on the ice surface above the probes. Conference Object Iceland University of Southampton: e-Prints Soton |
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Open Polar |
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University of Southampton: e-Prints Soton |
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ftsouthampton |
language |
English |
description |
Data collected by in situ subglacial probes has been used to guide a series of geotechnical tests on till. The testing provides an opportunity to develop a process-based understanding of movement patterns observed in the subglacial environment. The probes were deployed by the Glacsweb project at Skalafellsjökull, Iceland, in 2008 and 2012. They were emplaced in till below 80 m of ice and recorded a number of variables including pore pressure, case stress, movement and conductivity. During the winter of 2008-2009 cyclic pressure changes were recorded in the till. Repeated pore pressure increases of up to 20% occurred over a variable period of one to eight weeks. Each rise was followed by a sharp drop in pore pressure lasting up to a few days. A back pressure shear box was used to replicate the pore pressure changes whilst maintaining a constant horizontal shear stress and normal total stress to examine effects on deformation and strain rate. Till was collected for testing from the ice margin close to the probes in 2012 and remoulded for use in the back pressure shear box. General characterisation of the till was performed to benchmark it against previous work and then a series of pore pressure re-inflation tests were undertaken. These approximated the pore pressure variations observed in the field by linearly increasing pore pressure and so decreasing normal effective stress. The till displayed dilatancy-induced episodic increases in strain rate. These were regulated by consolidation that increased shear strength and so reduced strain rate. Strain rate variations were similar to ice velocity variations recorded by differential GPS deployed on the ice surface above the probes. |
format |
Conference Object |
author |
Hart, Jane |
spellingShingle |
Hart, Jane In situ sensing guided geotechnical modelling of subglacial deformation |
author_facet |
Hart, Jane |
author_sort |
Hart, Jane |
title |
In situ sensing guided geotechnical modelling of subglacial deformation |
title_short |
In situ sensing guided geotechnical modelling of subglacial deformation |
title_full |
In situ sensing guided geotechnical modelling of subglacial deformation |
title_fullStr |
In situ sensing guided geotechnical modelling of subglacial deformation |
title_full_unstemmed |
In situ sensing guided geotechnical modelling of subglacial deformation |
title_sort |
in situ sensing guided geotechnical modelling of subglacial deformation |
publishDate |
2014 |
url |
https://eprints.soton.ac.uk/432536/ |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
Hart, Jane (2014) In situ sensing guided geotechnical modelling of subglacial deformation. American Geophysical Union, Fall Meeting 2014, , San Francisco, United States. 15 - 19 Dec 2014. |
_version_ |
1772815914818863104 |