Ageing and cyclic behaviour of axially loaded piles driven in chalk

Buckley, R.M. , Jardine, R.J., Kontoe, S., Parker, D. and Schroeder, F.C. (2018) Ageing and cyclic behaviour of axially loaded piles driven in chalk. Geotechnique, 68(2), pp. 146-161. (doi: 10.1680/jgeot.17.P.012)

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This paper reports a programme of static and cyclic loading tests on seven open steel tubes driven in low- to medium-density chalk at a well-characterised test site, describing their response to driving, ageing in situ and loading under both static and cyclic conditions. Back analysis of dynamic monitoring identifies the distributions of notably low shaft resistances that develop during installation, showing that these depend strongly on the relative pile tip depth (h/R). The shaft capacities available to ‘virgin’ piles are shown to increase markedly after driving, following a hyperbolic trend that led to a fivefold gain after 250 days. Pre-failed piles do not follow the same trend when re-tested. Pile exhumation confirmed that driving remoulded the chalk, creating a puttified zone around the shaft. Excess pore water pressure dissipation, which is likely to have been rapid during and after driving, led to markedly lower water contents close to the shaft. Axial cyclic testing conducted around 250 days after driving led to a range of responses, from manifesting stable behaviour over 1000 cycles to failing after low numbers of cycles after developing sharp losses of static capacity. The dependence of permanent displacement on the cyclic loading parameters is explored and characterised. The experiments provide the first systematic study of which the authors are aware into the effects of undisturbed ageing and cyclic loading on previously unfailed piles driven in chalk. Potential predictive tools may now be tested against the reported field measurements.

Item Type:Articles
Additional Information:This study is part of a joint industry project led by Pedro Barbosa that is funded by Innovate UK (formerly the Technology Strategy Board), Iberdrola/Scottish Power Renewables and supported by the Geotechnical Consulting Group, London.
Glasgow Author(s) Enlighten ID:Buckley, Dr Roisin
Authors: Buckley, R.M., Jardine, R.J., Kontoe, S., Parker, D., and Schroeder, F.C.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Geotechnique
Publisher:ICE Publishing
ISSN (Online):1751-7656
Published Online:07 July 2017
Copyright Holders:Copyright © 2017 ICE Publishing
First Published:First published in Geotechnique 68(2): 146-161
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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