Sanvitale, N. and Bowman, E.T. orcid.org/0000-0001-7868-6688 (2017) Visualization of dominant stress-transfer mechanisms in experimental debris flows of different particle-size distribution. Canadian Geotechnical Journal, 54 (2). pp. 258-269. ISSN 0008-3674
Abstract
Physical modelling of debris flow in a small-scale flume has been carried out to investigate the internal stress-transfer mechanisms within unsteady, saturated, and segregating granular free-surface flows. Measurements of the internal velocity fields within model flows were obtained via planar laser–induced fluorescence and particle image velocimetry. Normalized velocity profiles taken at a section over the flow duration were found to essentially collapse onto a single curve, the shape of which was dependent on the particle-size distribution. While all flows exhibited internal basal slip and shear, for tests on well-graded materials that are most representative of debris flows, the shear rate was found to reduce towards the surface to near-zero, exhibiting near plug-flow. Dimensional analysis shows that particles of different size within these flows experienced different dominant stress-transfer mechanisms — frictional, collisional or viscous. Rapid grain-size segregation therefore is both due to and results in different modes of stress transfer within a single flow. This means that in a segregating and hence, stratified system, different flow regimes will act concurrently at microscale and mesoscale. Results highlight the complexity of debris flows, so that it may be undesirable to ascribe a single microscale constitutive behaviour throughout, and further calls into question the concept of flow regimes for debris flows based on bulk measurements.
Metadata
Authors/Creators: |
|
||||
---|---|---|---|---|---|
Copyright, Publisher and Additional Information: | © The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0) (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. | ||||
Keywords: | Debris flow; dimensionless number; flow regime; plane laser–induced fluorescence; flume model tests | ||||
Dates: |
|
||||
Institution: | The University of Sheffield | ||||
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Civil and Structural Engineering (Sheffield) | ||||
Funding Information: |
|
||||
Depositing User: | Symplectic Sheffield | ||||
Date Deposited: | 08 Feb 2017 15:10 | ||||
Last Modified: | 08 Jul 2020 11:00 | ||||
Published Version: | https://doi.org/10.1139/cgj-2015-0532 | ||||
Status: | Published | ||||
Publisher: | NRC Research Press | ||||
Refereed: | Yes | ||||
Identification Number: | https://doi.org/10.1139/cgj-2015-0532 | ||||
Related URLs: |