Bull, Daniel, Smethurst, Joel, Meijer, Gerrit, Sinclair, Ian, Pierron, Fabrice, Roose, Tiina, Powrie, William and Bengough, Glyn
(2022)
Modelling of stress transfer in root-reinforced soils informed by four-dimensional X-ray computed tomography and digital volume correlation data.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 478 (2257), [RSPA-2021-0210].
(doi:10.1098/rspa.2021.0210).
Abstract
Vegetation enhances soil shearing resistance through water uptake and root reinforcement. Analytical models for soils reinforced with roots rely on input parameters that are difficult to measure, leading to widely varying predictions of behaviour. The opaque heterogeneous nature of rooted soils results in complex soil-root interaction mechanisms that cannot easily be quantified. The authors measured, for the first time, the shear resistance and deformations of fallow, willow-rooted, and gorse-rooted soils during direct shear using X-ray computed tomography and digital volume correlation. Both species caused an increase in shear zone thickness, both initially and as shear progressed. Shear zone thickness peaked at up to 35 mm, often close to the thickest roots and towards the centre of the column. Root extension during shear was 10-30% less than the tri-linear root profile assumed in a Waldron-type model, owing to root curvature. Root analogues used to explore the root-soil interface behaviour suggested that root lateral branches play an important role in anchoring the roots. The Waldron-type model was modified to incorporate non-uniform shear zone thickness and growth, and accurately predicted the observed, up to seven-fold, increase in shear resistance of root-reinforced soil.
More information
Accepted/In Press date: 30 November 2021
Published date: 5 January 2022
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Funding Information:
effects of shear zone thickness in root-reinforced soils: Gorse G X-ray CT scans and DVC data. Zenodo Digital Repository. (doi:10.5281/zenodo.3556824) [48]. Bull, D.J., Smethurst, J.A., Meijer, G.J., Sinclair, I., Pierron, F., Roose, T., Powrie, W. & Bengough, A.G. 2020 Dataset for effects of shear zone thickness in root-reinforced soils: Fallow D X-ray CT scans and DVC data. Zenodo Digital Repository. (doi:10.5281/zenodo.3558069) [49]. Bull, D.J., Smethurst, J.A., Meijer, G.J., Sinclair, I., Pierron, F., Roose, T., Powrie, W. & Bengough, A.G. 2020 Dataset for effects of shear zone thickness in root-reinforced soils: Fallow P X-ray CT scans and DVC data. Zenodo Digital Repository. (doi:10.5281/zenodo.3558539) [50]. Bull, D.J., Smethurst, J.A., Meijer, G.J., Sinclair, I., Pierron, F., Roose, T., Powrie, W. & Bengough, A.G. 2020 Dataset for effects of shear zone thickness in root-reinforced soils. Zenodo Digital Repository. (doi:10.5281/zenodo.3558554) [51]. Authors’ contributions. D.J.B.: conceptualization, data curation, formal analysis, investigation, methodology, validation, visualization, writing—original draft and writing—review and editing; J.A.S.: conceptualization, formal analysis, funding acquisition, methodology, project administration, supervision and writing—review and editing; G.J.M.: formal analysis, methodology, writing—original draft and writing—review and editing; I.S.: conceptualization, funding acquisition, methodology, supervision and writing—review and editing; F.P.: conceptualization, funding acquisition, methodology, supervision and writing—review and editing; T.R.: conceptualization, funding acquisition, methodology, supervision and writing—review and editing; W.P.: conceptualization, funding acquisition, methodology, supervision and writing—review and editing; G.B.: conceptualization, funding acquisition, methodology, supervision and writing—review and editing All authors gave final approval for publication and agreed to be held accountable for the work performed therein. 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). 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. Acknowledgements. Dr Sonja Schmidt carried out the initial development work on the shear rig, with technical support from Harvey Skinner and Karl Scammell.
Publisher Copyright:
© 2022 The Authors.
Keywords:
Digital volume correlation, Direct shear, Root reinforcement, Shear zone thickness, Slope stability, X-ray computed tomography
Identifiers
Local EPrints ID: 452832
URI: http://eprints.soton.ac.uk/id/eprint/452832
ISSN: 1364-5021
PURE UUID: 6d462724-9aa1-4e71-8500-4a43e9693839
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Date deposited: 21 Dec 2021 17:51
Last modified: 18 Aug 2022 01:41
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