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The effect of the remoulded void ratio on unit shaft friction in small-displacement piles in chalk

The effect of the remoulded void ratio on unit shaft friction in small-displacement piles in chalk
The effect of the remoulded void ratio on unit shaft friction in small-displacement piles in chalk
Small-displacement pile driving in chalk produces an annulus of crushed and remoulded putty-like material through which shaft friction is believed to be mobilised. Ultimate shaft friction is assumed to be a function of the effective angle of friction of the putty chalk interface and the radial effective stress acting on the pile shaft. The mechanisms that affect the magnitude of the latter are not well understood. It is hypothesised that the stress levels attained during shaft friction mobilisation are related to the change in void ratio that takes place as structured chalk becomes crushed during pile installation. Therefore, a general notion exists that piles installed in dense chalks will mobilise larger shaft capacities than piles driven in more porous materials, and that this is related to the void ratio of the remoulded annulus. In this context, this paper presents the results of a series of monotonic constant volume simple shear tests conducted to assess the role of the void ratio in the mobilisation of shaft friction. Results suggest that void ratio is a controlling factor and that a state-based approach for the characterisation of void ratio-shaft friction relationships may be possible.
475-480
Institution of Civil Engineers
Alvarez Borges, F.J.
9d9257b8-7421-4fd2-b4e8-adef24abeeee
Clayton, C.R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Richards, D.J.
a58ea81e-443d-4dab-8d97-55d76a43d57e
Madhusudhan, B.N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Lawrence, James
Preene, Martin
Lawrence, Ursula
Buckley, Roisin
Alvarez Borges, F.J.
9d9257b8-7421-4fd2-b4e8-adef24abeeee
Clayton, C.R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Richards, D.J.
a58ea81e-443d-4dab-8d97-55d76a43d57e
Madhusudhan, B.N.
e139e3d3-2992-4579-b3f0-4eec3ddae98c
Lawrence, James
Preene, Martin
Lawrence, Ursula
Buckley, Roisin

Alvarez Borges, F.J., Clayton, C.R.I., Richards, D.J. and Madhusudhan, B.N. (2018) The effect of the remoulded void ratio on unit shaft friction in small-displacement piles 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. 475-480 . (doi:10.1680/eiccf.64072.475).

Record type: Conference or Workshop Item (Paper)

Abstract

Small-displacement pile driving in chalk produces an annulus of crushed and remoulded putty-like material through which shaft friction is believed to be mobilised. Ultimate shaft friction is assumed to be a function of the effective angle of friction of the putty chalk interface and the radial effective stress acting on the pile shaft. The mechanisms that affect the magnitude of the latter are not well understood. It is hypothesised that the stress levels attained during shaft friction mobilisation are related to the change in void ratio that takes place as structured chalk becomes crushed during pile installation. Therefore, a general notion exists that piles installed in dense chalks will mobilise larger shaft capacities than piles driven in more porous materials, and that this is related to the void ratio of the remoulded annulus. In this context, this paper presents the results of a series of monotonic constant volume simple shear tests conducted to assess the role of the void ratio in the mobilisation of shaft friction. Results suggest that void ratio is a controlling factor and that a state-based approach for the characterisation of void ratio-shaft friction relationships may be possible.

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remoulded void ratio on shat friction - Alvarez-Borges 2018
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e-pub ahead of print date: 16 August 2018
Published date: 2018

Identifiers

Local EPrints ID: 426467
URI: https://eprints.soton.ac.uk/id/eprint/426467
PURE UUID: 58acbc24-a8e3-4e2b-81a6-2068e3c45812
ORCID for F.J. Alvarez Borges: ORCID iD orcid.org/0000-0002-6940-9918
ORCID for B.N. Madhusudhan: ORCID iD orcid.org/0000-0002-2570-5934

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Date deposited: 28 Nov 2018 17:30
Last modified: 14 Mar 2019 01:33

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Contributors

Author: F.J. Alvarez Borges ORCID iD
Author: C.R.I. Clayton
Author: D.J. Richards
Editor: James Lawrence
Editor: Martin Preene
Editor: Ursula Lawrence
Editor: Roisin Buckley

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