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Article: Particle elongation and deposition effect to macroscopic and microscopic responses of numerical direct shear tests

TitleParticle elongation and deposition effect to macroscopic and microscopic responses of numerical direct shear tests
Authors
KeywordsDilatancy
Discrete element method
Packing
Particle shape
Shear strength
Issue Date2010
PublisherASTM International. The Journal's web site is located at http://journalsip.astm.org/JOURNALS/GEOTECH/gtj%5Fhome.html
Citation
Geotechnical Testing Journal, 2010, v. 33 n. 4, p. 1-12 How to Cite?
AbstractIn this study, a series of numerical direct shear tests is carried out by the three-dimensional discrete element method. The box is filled by either spherical or elongated particles of mono-size. Particles of three different aspect ratios (defined as length/width of a particle), 1 (i.e., spherical), 1.5 and 2, are modeled. Elongated particles are created by joining primary spherical balls together, and no particle breakage is allowed. The granular specimen is prepared by either depositional method or by random generation of particles inside the box. By controlling the interparticle friction coefficient, number of particles and deposited direction, particle assemblies with very close initial density but different packing or micro-structure can be obtained. Various measurement spheres are defined at different locations of the box to reveal the local stresses by considering interparticle interaction forces. The results show a significant spatial variations of the stresses, which deviate noticeably from the global measurements recorded at the box boundaries. Furthermore, global measurements appreciably conclude higher ultimate strength of the assemblage as compared to the local ones from the measurement spheres, regardless the particles' aspect ratio and packing. The ultimate shear strength increases with particles' aspect ratio. Initial fabric affects the ultimate shear strength such that the assemblage having more particles aligning parallel to the shear direction (DepS) yields the lowest strength. On the other hand randomly packed assemblage exhibits the highest strength. Furthermore, DepS specimen shows the least amount of dilation. Particle orientation is described by a tensorial parameter, and its evolution during shear is discussed. Analysis shows that only particles close to the shear plane exhibit significant rotation and thus a noticeable change in the fabric. It is found that the evolution of fabric tensor is closely linked to the macroscopic response of an assemblage. Fabric analysis helps to explain the macroscopic responses from a microscopic particle rearrangement perspective. Copyright © 2010 by ASTM International.
Persistent Identifierhttp://hdl.handle.net/10722/91234
ISSN
2015 Impact Factor: 0.663
2015 SCImago Journal Rankings: 1.289
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorYan, WMen_HK
dc.date.accessioned2010-09-17T10:15:18Z-
dc.date.available2010-09-17T10:15:18Z-
dc.date.issued2010en_HK
dc.identifier.citationGeotechnical Testing Journal, 2010, v. 33 n. 4, p. 1-12en_HK
dc.identifier.issn0149-6115en_HK
dc.identifier.urihttp://hdl.handle.net/10722/91234-
dc.description.abstractIn this study, a series of numerical direct shear tests is carried out by the three-dimensional discrete element method. The box is filled by either spherical or elongated particles of mono-size. Particles of three different aspect ratios (defined as length/width of a particle), 1 (i.e., spherical), 1.5 and 2, are modeled. Elongated particles are created by joining primary spherical balls together, and no particle breakage is allowed. The granular specimen is prepared by either depositional method or by random generation of particles inside the box. By controlling the interparticle friction coefficient, number of particles and deposited direction, particle assemblies with very close initial density but different packing or micro-structure can be obtained. Various measurement spheres are defined at different locations of the box to reveal the local stresses by considering interparticle interaction forces. The results show a significant spatial variations of the stresses, which deviate noticeably from the global measurements recorded at the box boundaries. Furthermore, global measurements appreciably conclude higher ultimate strength of the assemblage as compared to the local ones from the measurement spheres, regardless the particles' aspect ratio and packing. The ultimate shear strength increases with particles' aspect ratio. Initial fabric affects the ultimate shear strength such that the assemblage having more particles aligning parallel to the shear direction (DepS) yields the lowest strength. On the other hand randomly packed assemblage exhibits the highest strength. Furthermore, DepS specimen shows the least amount of dilation. Particle orientation is described by a tensorial parameter, and its evolution during shear is discussed. Analysis shows that only particles close to the shear plane exhibit significant rotation and thus a noticeable change in the fabric. It is found that the evolution of fabric tensor is closely linked to the macroscopic response of an assemblage. Fabric analysis helps to explain the macroscopic responses from a microscopic particle rearrangement perspective. Copyright © 2010 by ASTM International.en_HK
dc.languageengen_HK
dc.publisherASTM International. The Journal's web site is located at http://journalsip.astm.org/JOURNALS/GEOTECH/gtj%5Fhome.htmlen_HK
dc.relation.ispartofGeotechnical Testing Journalen_HK
dc.subjectDilatancyen_HK
dc.subjectDiscrete element methoden_HK
dc.subjectPackingen_HK
dc.subjectParticle shapeen_HK
dc.subjectShear strengthen_HK
dc.titleParticle elongation and deposition effect to macroscopic and microscopic responses of numerical direct shear testsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0149-6115&volume=33&issue=4&spage=&epage=&date=2010&atitle=Particle+elongation+and+deposition+effect+to+macroscopic+and+microscopic+responses+of+numerical+direct+shear+tests-
dc.identifier.emailYan, WM:ryanyan@hku.hken_HK
dc.identifier.authorityYan, WM=rp01400en_HK
dc.description.naturelink_to_OA_fulltext-
dc.identifier.scopuseid_2-s2.0-77954870311en_HK
dc.identifier.hkuros172649-
dc.identifier.hkuros187989-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77954870311&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume33en_HK
dc.identifier.issue4en_HK
dc.identifier.spage1-
dc.identifier.epage12-
dc.identifier.isiWOS:000296689800010-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridYan, WM=35369531200en_HK

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