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Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation

Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation
Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation

Vegetation on railway or highway slopes can improve slope stability through the generation of soil pore water suctions by plant transpiration and mechanical soil reinforcement by the roots. To incorporate the enhanced shearing resistance and stiffness of root-reinforced soils in stability calculations, it is necessary to understand and quantify its effectiveness. This requires integrated and sophisticated experimental and multi-scale modelling approaches to develop an understanding of the processes at different length scales, from individual root–soil interaction through to full soil-profile or slope scale. One of the challenges with multi-scale models is ensuring that they sufficiently closely represent real behaviour. This requires calibration against detailed high-quality and data-rich experiments. This study presents a novel experimental methodology, which combines in situ direct shear loading of a willow root-reinforced soil with X-ray computed tomography to capture the three-dimensional chronology of soil and root deformation within the shear zone. Digital volume correlation (DVC) analysis was applied.

Digital volume correlation, Direct shear, Root reinforcement, Slope stability, Soil science, X-ray computed tomography
1364-5021
1-23
Bull, Daniel
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Smethurst, Joel
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Sinclair, Ian
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Pierron, Fabrice
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Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Bengough, Anthony G.
ac1f754e-002c-44f6-8907-8771a4cd1fd3
Bull, Daniel
3569ba02-89de-4398-a14d-02c3f9b4eab2
Smethurst, Joel
8f30880b-af07-4cc5-a0fe-a73f3dc30ab5
Sinclair, Ian
6005f6c1-f478-434e-a52d-d310c18ade0d
Pierron, Fabrice
a1fb4a70-6f34-4625-bc23-fcb6996b79b4
Roose, Tiina
3581ab5b-71e1-4897-8d88-59f13f3bccfe
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Bengough, Anthony G.
ac1f754e-002c-44f6-8907-8771a4cd1fd3

Bull, Daniel, Smethurst, Joel, Sinclair, Ian, Pierron, Fabrice, Roose, Tiina, Powrie, William and Bengough, Anthony G. (2020) Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 476 (2237), 1-23, [20190838]. (doi:10.1098/rspa.2019.0838).

Record type: Article

Abstract

Vegetation on railway or highway slopes can improve slope stability through the generation of soil pore water suctions by plant transpiration and mechanical soil reinforcement by the roots. To incorporate the enhanced shearing resistance and stiffness of root-reinforced soils in stability calculations, it is necessary to understand and quantify its effectiveness. This requires integrated and sophisticated experimental and multi-scale modelling approaches to develop an understanding of the processes at different length scales, from individual root–soil interaction through to full soil-profile or slope scale. One of the challenges with multi-scale models is ensuring that they sufficiently closely represent real behaviour. This requires calibration against detailed high-quality and data-rich experiments. This study presents a novel experimental methodology, which combines in situ direct shear loading of a willow root-reinforced soil with X-ray computed tomography to capture the three-dimensional chronology of soil and root deformation within the shear zone. Digital volume correlation (DVC) analysis was applied.

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Accepted/In Press date: 21 April 2020
e-pub ahead of print date: 20 May 2020
Published date: 27 May 2020
Additional Information: Funding Information: Data accessibility. Data used in this study has been made available on the Zenodo digital repository. Bull, D.J., Smethurst, J.A., Sinclair, I., Pierron, F., Roose, T., Powrie, W. & Bengough, A.G. 2020 Noise study data for: Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation. Zenodo Digital Repository (https://doi.org/10.5281/ zenodo.3361832) [53]. Bull, D.J., Smethurst, J.A., Sinclair, I., Pierron, F., Roose, T., Powrie, W. & Bengough, A.G. 2020 Data for: Mechanisms of root-reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation. Zenodo Digital Repository (https://doi.org/10.5281/zenodo.3352268) [54]. Authors’contributions. D.J.B.carriedoutthedesignofthedirectsheartestrig(hardware,softwareandelectronics), X-ray CT scanning, data processing, data analysis and write up of the paper. J.A.S. was the principal investigator on the project, made extensive revisions to the manuscript and provided expertise in soil science and civil engineering. I.S. revised the manuscript and provided expertise in X-ray CT. F.P. provided extensive revision to the manuscript and provided expertise in digital image correlation techniques. T.R. provided revisions to the manuscript and provided expertise in soil–root behaviour. W.P. provided revisions to the manuscript and support to soil mechanics. A.G.B. provided some revision to the manuscript and extensive advice for direct shear tests with prior experience on the behaviour of willow that helped the design methodology of the experiments. All authors give final approval for publication. Competing interests. We declare we have no competing interests. Funding. This research was funded by the UK Engineering and Physical Sciences Research Council grant nos. EP/M020177/1 and EP/M020355/1, as part of a collaboration between the University of Southampton, University of Dundee, University of Aberdeen, Durham University and the James Hutton Institute. The James Hutton Institute receives funding from the Scottish Government (Rural & Environmental Services & Analytical Services Division). Acknowledgements. Dr Sonja Schmidt carried out the initial development work on the shear rig, with technical support from Harvey Skinner and Karl Scammell. The authors acknowledge the µ-VIS X-ray Imaging Centre at the University of Southampton for provision of tomographic imaging facilities, supported by EPSRC grant no. EP/H01506X. Publisher Copyright: © 2020 The Author(s) Published by the Royal Society. All rights reserved.
Keywords: Digital volume correlation, Direct shear, Root reinforcement, Slope stability, Soil science, X-ray computed tomography

Identifiers

Local EPrints ID: 439699
URI: http://eprints.soton.ac.uk/id/eprint/439699
ISSN: 1364-5021
PURE UUID: a0380c23-fcf6-4bf0-8101-01045907feb3
ORCID for Daniel Bull: ORCID iD orcid.org/0000-0001-6711-6153
ORCID for Fabrice Pierron: ORCID iD orcid.org/0000-0003-2813-4994
ORCID for Tiina Roose: ORCID iD orcid.org/0000-0001-8710-1063
ORCID for William Powrie: ORCID iD orcid.org/0000-0002-2271-0826

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Date deposited: 30 Apr 2020 16:30
Last modified: 01 Dec 2022 02:42

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Contributors

Author: Daniel Bull ORCID iD
Author: Joel Smethurst
Author: Ian Sinclair
Author: Fabrice Pierron ORCID iD
Author: Tiina Roose ORCID iD
Author: William Powrie ORCID iD
Author: Anthony G. Bengough

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