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Article: Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains
Title | Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains | ||||
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Authors | |||||
Keywords | Clays Creep Dynamics Laboratory tests Stiffness Time dependence | ||||
Issue Date | 2010 | ||||
Publisher | Thomas Telford (ICE Publishing). The Journal's web site is located at http://www.geotechnique-ice.com | ||||
Citation | Geotechnique, 2010, v. 60 n. 10, p. 751-763 How to Cite? | ||||
Abstract | This paper attempts to bridge the gap between the wellknown characteristics of strain rate-independent elastic stiffness and of the time-dependent behaviour of clays at large strains. Effects of acceleration, strain rate and ageing are examined in the very small to small strain region, using results from tests on reconstituted London Clay and kaolin. Static measurements of the shear modulus at small strains, using local instrumentation, indicate that the shear modulus is rate-independent when the soil is subjected to elastic deformations only. Most often, in practice, soil specimens are left to rest between the compression and shearing stages, until deformations associated with creep become negligible. The testing strain rate imposed upon shearing induces a temporary acceleration of strains, which results in very high measured stiffnesses. Test data show, however, that when the shearing axial strain rate is of the same order of magnitude as that measured at the end of the compression/creep stage, the remaining plastic creep strains influence the measured stiffness, which is then measured to be comparatively low. Test data also seem to show that temporary strain acceleration may hide effects of recent stress path rotation. Additionally, bender element tests were performed during isotropic compression tests with changes in stress rate and creep stages. The data indicate that the strain rate affects the value of the dynamic shear modulus of the soil. It is suggested that the increase in dynamic shear modulus during short-term creep is caused by mechanisms linked to the gradual decrease in strain rate during creep, but further investigation would be needed to clarify which physical mechanisms. A new method to account for strain rate in evaluating the dynamic shear modulus of normally consolidated reconstituted clays is finally proposed. | ||||
Persistent Identifier | http://hdl.handle.net/10722/137228 | ||||
ISSN | 2023 Impact Factor: 4.2 2023 SCImago Journal Rankings: 1.791 | ||||
ISI Accession Number ID |
Funding Information: The authors would like to thank Imperial College for providing the rotary cores of undisturbed London Clay, without which this research could not have been carried out, and Dr Coop for his guidance and help with the experimental testing at the start of the research. The authors are also very grateful to Dr Joao Rio and Mr Steve Ackerley for their invaluable help in devising and building the bender elements. The research was made possible through funding from the Engineering and Physical Sciences Research Council's (EPSRC's) Cooperation Awards in Science and Engineering (CASE) in collaboration with Ove Arup and Partners. | ||||
References |
DC Field | Value | Language |
---|---|---|
dc.contributor.author | Sorensen, KK | en_HK |
dc.contributor.author | Baudet, BA | en_HK |
dc.contributor.author | Simpson, B | en_HK |
dc.date.accessioned | 2011-08-26T14:21:35Z | - |
dc.date.available | 2011-08-26T14:21:35Z | - |
dc.date.issued | 2010 | en_HK |
dc.identifier.citation | Geotechnique, 2010, v. 60 n. 10, p. 751-763 | en_HK |
dc.identifier.issn | 0016-8505 | en_HK |
dc.identifier.uri | http://hdl.handle.net/10722/137228 | - |
dc.description.abstract | This paper attempts to bridge the gap between the wellknown characteristics of strain rate-independent elastic stiffness and of the time-dependent behaviour of clays at large strains. Effects of acceleration, strain rate and ageing are examined in the very small to small strain region, using results from tests on reconstituted London Clay and kaolin. Static measurements of the shear modulus at small strains, using local instrumentation, indicate that the shear modulus is rate-independent when the soil is subjected to elastic deformations only. Most often, in practice, soil specimens are left to rest between the compression and shearing stages, until deformations associated with creep become negligible. The testing strain rate imposed upon shearing induces a temporary acceleration of strains, which results in very high measured stiffnesses. Test data show, however, that when the shearing axial strain rate is of the same order of magnitude as that measured at the end of the compression/creep stage, the remaining plastic creep strains influence the measured stiffness, which is then measured to be comparatively low. Test data also seem to show that temporary strain acceleration may hide effects of recent stress path rotation. Additionally, bender element tests were performed during isotropic compression tests with changes in stress rate and creep stages. The data indicate that the strain rate affects the value of the dynamic shear modulus of the soil. It is suggested that the increase in dynamic shear modulus during short-term creep is caused by mechanisms linked to the gradual decrease in strain rate during creep, but further investigation would be needed to clarify which physical mechanisms. A new method to account for strain rate in evaluating the dynamic shear modulus of normally consolidated reconstituted clays is finally proposed. | en_HK |
dc.language | eng | en_US |
dc.publisher | Thomas Telford (ICE Publishing). The Journal's web site is located at http://www.geotechnique-ice.com | en_HK |
dc.relation.ispartof | Geotechnique | en_HK |
dc.rights | Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees | - |
dc.subject | Clays | en_HK |
dc.subject | Creep | en_HK |
dc.subject | Dynamics | en_HK |
dc.subject | Laboratory tests | en_HK |
dc.subject | Stiffness | en_HK |
dc.subject | Time dependence | en_HK |
dc.title | Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains | en_HK |
dc.type | Article | en_HK |
dc.identifier.email | Baudet, BA:baudet@hku.hk | en_HK |
dc.identifier.authority | Baudet, BA=rp01303 | en_HK |
dc.description.nature | published_or_final_version | - |
dc.identifier.doi | 10.1680/geot.07.D.147 | en_HK |
dc.identifier.scopus | eid_2-s2.0-79551582069 | en_HK |
dc.identifier.hkuros | 190256 | en_US |
dc.relation.references | http://www.scopus.com/mlt/select.url?eid=2-s2.0-79551582069&selection=ref&src=s&origin=recordpage | en_HK |
dc.identifier.volume | 60 | en_HK |
dc.identifier.issue | 10 | en_HK |
dc.identifier.spage | 751 | en_HK |
dc.identifier.epage | 763 | en_HK |
dc.identifier.isi | WOS:000281708100002 | - |
dc.publisher.place | United Kingdom | en_HK |
dc.identifier.scopusauthorid | Sorensen, KK=36994189400 | en_HK |
dc.identifier.scopusauthorid | Baudet, BA=15841467600 | en_HK |
dc.identifier.scopusauthorid | Simpson, B=7102222020 | en_HK |
dc.identifier.issnl | 0016-8505 | - |