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Modelling of stress transfer in root-reinforced soils informed by four-dimensional X-ray computed tomography and digital volume correlation data

Modelling of stress transfer in root-reinforced soils informed by four-dimensional X-ray computed tomography and digital volume correlation data
Modelling of stress transfer in root-reinforced soils informed by four-dimensional X-ray computed tomography and digital volume correlation data
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.
Direct shear, Slope stability, Root reinforcement, Digital volume correlation, X-ray computed tomography, Shear zone thickness
1364-5021
Bull, Daniel
3569ba02-89de-4398-a14d-02c3f9b4eab2
Smethurst, Joel
8f30880b-af07-4cc5-a0fe-a73f3dc30ab5
Meijer, Gerrit
7b9009ee-fc42-434b-82ab-827cf7959e79
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, Glyn
916e33a7-985b-4b01-a76c-acdfcdd15fdb
Bull, Daniel
3569ba02-89de-4398-a14d-02c3f9b4eab2
Smethurst, Joel
8f30880b-af07-4cc5-a0fe-a73f3dc30ab5
Meijer, Gerrit
7b9009ee-fc42-434b-82ab-827cf7959e79
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, Glyn
916e33a7-985b-4b01-a76c-acdfcdd15fdb

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).

Record type: Article

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.

Text
Bull et al 2021 Revised manuscript v5 FINAL - Accepted Manuscript
Available under License Creative Commons Attribution.
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More information

Accepted/In Press date: 30 November 2021
Published date: 5 January 2022
Keywords: Direct shear, Slope stability, Root reinforcement, Digital volume correlation, X-ray computed tomography, Shear zone thickness

Identifiers

Local EPrints ID: 452832
URI: http://eprints.soton.ac.uk/id/eprint/452832
ISSN: 1364-5021
PURE UUID: 6d462724-9aa1-4e71-8500-4a43e9693839
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

Catalogue record

Date deposited: 21 Dec 2021 17:51
Last modified: 09 Jan 2022 03:33

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Contributors

Author: Daniel Bull ORCID iD
Author: Joel Smethurst
Author: Gerrit Meijer
Author: Ian Sinclair
Author: Fabrice Pierron ORCID iD
Author: Tiina Roose ORCID iD
Author: William Powrie ORCID iD
Author: Glyn Bengough

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