Large Scale Physical Modelling of Particle Size Segregation in Granular Flows
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Authors
Kimball, Julia
Date
Type
thesis
Language
eng
Keyword
granular flows , particle size segregation , debris flows , large scale physical modelling , landslide flume , saturated granular flows , multi-component flows , tridisperse material
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Abstract
Particle size segregation is a phenomenon observed in granular flows of mixed particle sizes resulting in preferential sorting within the flow. In a geohazards context, landslides comprised of a wide range of particle sizes, such as debris flows, therefore exhibit flow structures arising from significant particle size segregation. Size segregation in the vertical direction results in the upwards coarse grading of material, segregation in the longitudinal direction results in the development of a coarse grained flow front, transition zone and fine grained thinning flow tail. Therefore particle size segregation will significantly influence the mobility of the flow, the development of debris fans, and the resulting impact forces to be expected when designing barriers and containment structures to mitigate these geohazards. However, the flow dynamics and depositional processes occurring along the centerline of segregating granular flows is understudied in both dry and saturated flows. Experimental datasets are required to further understanding of the dynamics of segregation and to serve as a basis of comparison to numerical and theoretical model outcomes. Two series of large scale tridisperse granular flow experiments were performed to provide insight on this knowledge gap. The objective of the first test series was to examine particle size segregation observed from a flume sidewall to segregation observed along the centerline of a deposit. A series of replicate tests were conducted to assess different internal transparent plane centerline deposit sampling methods. The results of this testing series demonstrated significant differences between sidewall observations and deposit centerline observations of segregation. The objective of the second test series was to examine particle size segregation differences between dry and saturated flows through comparison of flume experiments conducted with the source volume in a dry or saturated state. For the conditions tested, the travel distance of both flows was sufficient to achieve a mature state of segregation expressed in terms of segregation along the normalized length of the deposit. We anticipate that the dry and saturated large-scale tridisperse flow experimental datasets produced by this work will be used in the calibration of both numerical and theoretical models of particle size segregation.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.