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Application of X-ray computed tomography to investigate pile penetration mechanisms in chalk

Application of X-ray computed tomography to investigate pile penetration mechanisms in chalk
Application of X-ray computed tomography to investigate pile penetration mechanisms in chalk
The installation of displacement piles in chalk involves the crushing, remoulding and densifying of the material under the pile tip. This remoulded material forms an annulus around the installed pile. Shaft friction can be expected to be significantly affected by the characteristics of this annulus. However, research on its attributes and the mechanisms behind its origin is scarce. This paper explores the use of non-destructive 3D X-ray computed tomography (XCT) imaging to determine the changes in bulk density associated with chalk crushing and remoulding during the penetration of a mini-pile into an intact chalk specimen. The use of XCT allowed for the estimation of the thickness and general geometry of the remoulded chalk annulus, as well as its 3D visualisation for the first time. Preliminary results suggest that pile installation in the radially confined chalk specimen took place, primarily, by crushing and densification of the chalk under the pile tip. This led to the formation of an annulus of variable thickness and density. By implementing a mass-balance analysis, the post-pile installation XCT-derived mass was found to differ by less than 0.4% from the pre-installation mass, which gives confidence in the accuracy of XCT imaging in detecting local changes in bulk density. In general, the results show that this technology has potential for contributing to the understanding of the development of pile loading capacity in chalk.
595-570
Institution of Civil Engineers
Alvarez-Borges, F.J.
9d9257b8-7421-4fd2-b4e8-adef24abeeee
Richards, D.J.
a58ea81e-443d-4dab-8d97-55d76a43d57e
Clayton, Christopher
8397d691-b35b-4d3f-a6d8-40678f233869
Ahmed, S.I.
37570e92-ba6b-4e03-9144-c70fa7722c51
Lawrence, James
Preene, Martin
Lawrence, Ursula
Buckley, Roisin
Alvarez-Borges, F.J.
9d9257b8-7421-4fd2-b4e8-adef24abeeee
Richards, D.J.
a58ea81e-443d-4dab-8d97-55d76a43d57e
Clayton, Christopher
8397d691-b35b-4d3f-a6d8-40678f233869
Ahmed, S.I.
37570e92-ba6b-4e03-9144-c70fa7722c51
Lawrence, James
Preene, Martin
Lawrence, Ursula
Buckley, Roisin

Alvarez-Borges, F.J., Richards, D.J., Clayton, Christopher and Ahmed, S.I. (2018) Application of X-ray computed tomography to investigate pile penetration mechanisms in chalk. Lawrence, James, Preene, Martin, Lawrence, Ursula and Buckley, Roisin (eds.) In Engineering in Chalk: Proceedings of the Chalk 2018 Conference. Institution of Civil Engineers. pp. 595-570 .

Record type: Conference or Workshop Item (Paper)

Abstract

The installation of displacement piles in chalk involves the crushing, remoulding and densifying of the material under the pile tip. This remoulded material forms an annulus around the installed pile. Shaft friction can be expected to be significantly affected by the characteristics of this annulus. However, research on its attributes and the mechanisms behind its origin is scarce. This paper explores the use of non-destructive 3D X-ray computed tomography (XCT) imaging to determine the changes in bulk density associated with chalk crushing and remoulding during the penetration of a mini-pile into an intact chalk specimen. The use of XCT allowed for the estimation of the thickness and general geometry of the remoulded chalk annulus, as well as its 3D visualisation for the first time. Preliminary results suggest that pile installation in the radially confined chalk specimen took place, primarily, by crushing and densification of the chalk under the pile tip. This led to the formation of an annulus of variable thickness and density. By implementing a mass-balance analysis, the post-pile installation XCT-derived mass was found to differ by less than 0.4% from the pre-installation mass, which gives confidence in the accuracy of XCT imaging in detecting local changes in bulk density. In general, the results show that this technology has potential for contributing to the understanding of the development of pile loading capacity in chalk.

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XCT for pile penetration in chalk - Alvarez-Borges 2018
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Published date: 2018

Identifiers

Local EPrints ID: 426466
URI: https://eprints.soton.ac.uk/id/eprint/426466
PURE UUID: 14c8497c-21cd-4f87-b7f2-85c8b1bff3a8
ORCID for F.J. Alvarez-Borges: ORCID iD orcid.org/0000-0002-6940-9918
ORCID for S.I. Ahmed: ORCID iD orcid.org/0000-0002-3290-3592

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Date deposited: 28 Nov 2018 17:30
Last modified: 14 Mar 2019 01:41

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Contributors

Author: F.J. Alvarez-Borges ORCID iD
Author: D.J. Richards
Author: S.I. Ahmed ORCID iD
Editor: James Lawrence
Editor: Martin Preene
Editor: Ursula Lawrence
Editor: Roisin Buckley

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