Persistent Link:
http://hdl.handle.net/10150/195563
Title:
The Influence of Grain Shape on Dilatancy
Author:
Cox, Melissa Reiko Brooke
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Grain shape is a key factor affecting the mechanical properties of granular materials. However, grain shape quantification techniques to distinguish one granular material from another have not reached a stage of development for inclusion in modeling the behavior of granular materials. Part of the problem is the equipment of choice for grain shape measurement is the scanning electron microscope. This is a relatively expensive and complex device. In this research, a practical approach using light microscopy to quantify grain shape and to identify the key shape parameters that can distinguish grains was investigated. A light microscope was found to produce grain images with sufficient quality for the purpose of observing the grain shape profile. Several grain shape parameters were determined for eight different sands - four sands chosen for this study and four sands from an outside source. Six of these - Circularity, Roundness, Sphericity, Aspect Ratio, Compactness and ModRatio - are shown to be the key shape parameters that differentiate these sand grains.Relationships between the six key grain shape parameters and dilatancy were developed to enable a better understanding of the mechanics of granular materials and for potential use in practice. Data to build the relationships were obtained using a light microscope, digital image processing software (ImageJ), and direct shear tests on four uniform sands composed of grains with varying, somewhat-homogeneous, shape profiles - ranging from very rounded grains in one granular conglomerate to very angular shaped grains in another.A Weighted Single Sand Shape Factor (WSSSF) was derived from all of the six key shape parameters was developed using Weighted Factor Analysis. A good correlation was found to exist between dilatancy and WSSSF. The correlation also incorporates normal effective stress, relative density and the critical state friction angle. Verification was conducted through the introduction of a subangular to subrounded sand that was not used in building the correlation. The correlation proved to provide a good estimate of the dilatancy of sands based on the physical properties of grains and the applied loading.
Type:
text; Electronic Dissertation
Keywords:
Dilatancy; Direct shear testing; Grain shape; Granular materials; Microscopy; Shear strength
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Civil Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Budhu, Muniram
Committee Chair:
Budhu, Muniram

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleThe Influence of Grain Shape on Dilatancyen_US
dc.creatorCox, Melissa Reiko Brookeen_US
dc.contributor.authorCox, Melissa Reiko Brookeen_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractGrain shape is a key factor affecting the mechanical properties of granular materials. However, grain shape quantification techniques to distinguish one granular material from another have not reached a stage of development for inclusion in modeling the behavior of granular materials. Part of the problem is the equipment of choice for grain shape measurement is the scanning electron microscope. This is a relatively expensive and complex device. In this research, a practical approach using light microscopy to quantify grain shape and to identify the key shape parameters that can distinguish grains was investigated. A light microscope was found to produce grain images with sufficient quality for the purpose of observing the grain shape profile. Several grain shape parameters were determined for eight different sands - four sands chosen for this study and four sands from an outside source. Six of these - Circularity, Roundness, Sphericity, Aspect Ratio, Compactness and ModRatio - are shown to be the key shape parameters that differentiate these sand grains.Relationships between the six key grain shape parameters and dilatancy were developed to enable a better understanding of the mechanics of granular materials and for potential use in practice. Data to build the relationships were obtained using a light microscope, digital image processing software (ImageJ), and direct shear tests on four uniform sands composed of grains with varying, somewhat-homogeneous, shape profiles - ranging from very rounded grains in one granular conglomerate to very angular shaped grains in another.A Weighted Single Sand Shape Factor (WSSSF) was derived from all of the six key shape parameters was developed using Weighted Factor Analysis. A good correlation was found to exist between dilatancy and WSSSF. The correlation also incorporates normal effective stress, relative density and the critical state friction angle. Verification was conducted through the introduction of a subangular to subrounded sand that was not used in building the correlation. The correlation proved to provide a good estimate of the dilatancy of sands based on the physical properties of grains and the applied loading.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectDilatancyen_US
dc.subjectDirect shear testingen_US
dc.subjectGrain shapeen_US
dc.subjectGranular materialsen_US
dc.subjectMicroscopyen_US
dc.subjectShear strengthen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineCivil Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBudhu, Muniramen_US
dc.contributor.chairBudhu, Muniramen_US
dc.contributor.committeememberHaldar, Achintyaen_US
dc.contributor.committeememberDesai, Chandrakant Sen_US
dc.contributor.committeememberKemeny, John Men_US
dc.identifier.proquest10053en_US
dc.identifier.oclc659750472en_US
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