Subglacial clast/bed contact forces

dc.contributor.author Byers, John
dc.contributor.author Cohen, Denis
dc.contributor.author Iverson, Neal
dc.contributor.author Iverson, Neal
dc.contributor.department Geological and Atmospheric Sciences
dc.date 2018-02-18T09:28:24.000
dc.date.accessioned 2020-06-30T04:03:26Z
dc.date.available 2020-06-30T04:03:26Z
dc.date.copyright Sun Jan 01 00:00:00 UTC 2012
dc.date.issued 2012-02-01
dc.description.abstract <p>A laboratory device was built to measure the forces that ice exerts on a 0.05 m diameter rigid plastic sphere in two different configurations: in contact with a flat bed or isolated from the bed. Measurements indicated that bed-normal contact forces were 1.8 times larger than drag forces due to creeping flow past a slippery sphere isolated from the bed. Measurements of forces as a function of the bed-normal ice velocity, estimations of the ice viscosity parameter and observations of markers in the ice indicate ice is Newtonian with a viscosity of ∼1.3 × 1011 Pa s. Newtonian behavior is expected due to small and transient stresses. A model of regelation indicates that it had a negligible (<5%) influence on forces. Water pressure in the cavity beneath the sphere in contact with the bed had a likewise negligible influence on contact forces. When no cavity is present, drag forces can be correctly estimated using Stokes's law (Newtonian viscosity) for a slippery sphere. The same law with a bed-enhancement factor of 1.8 is appropriate for estimating bed-normal contact forces. These results reinforce previous laboratory measurements and theories but provide no support for explanations of high debris/bed friction or rates of abrasion that depend on high contact forces.</p>
dc.description.comments <p>This article is from <em>Journal of Glaciology </em>58 (2012): 89, doi:<a href="http://dx.doi.org/doi.org/10.3189/2012JoG11J126" target="_blank">10.3189/2012JoG11J126</a>. Posted with permission.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/ge_at_pubs/150/
dc.identifier.articleid 1137
dc.identifier.contextkey 10068602
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath ge_at_pubs/150
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/38082
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/ge_at_pubs/150/2012_Iverson_SubglacialClast.pdf|||Fri Jan 14 20:34:16 UTC 2022
dc.source.uri doi.org/10.3189/2012JoG11J126
dc.subject.disciplines Geomorphology
dc.subject.disciplines Glaciology
dc.title Subglacial clast/bed contact forces
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication 8f9617fd-0ee4-4473-b7bb-ef722542e676
relation.isOrgUnitOfPublication 29272786-4c4a-4d63-98d6-e7b6d6730c45
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