Effective stress regime around a jacked steel pile during installation, ageing and load testing in chalk

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Title: Effective stress regime around a jacked steel pile during installation, ageing and load testing in chalk
Author(s): Buckley, R
Jardine, R
Kontoe, S
Lehane, B
Item Type: Journal Article
Abstract: This paper reports experiments with 102 mm diameter closed-ended instrumented Imperial College piles (ICPs) jacked into low- to medium-density chalk at a well-characterized UK test site. The “ICP” instruments allowed the effective stress regime surrounding the pile shaft to be tracked during pile installation, equalization periods of up to 2.5 months, and load testing under static tension and one-way axial cyclic loading. Installation resistances are shown to be dominated by the pile tip loads. Low installation shaft stresses and radial effective stresses were measured that correlated with local cone penetration test (CPT) tip resistances. Marked shaft total stress reductions and steep stress gradients are demonstrated in the vicinity of the pile tip. The local interface shaft effective stress paths developed during static and cyclic loading displayed trends that resemble those seen in comparable tests in sands. Shaft failure followed the Coulomb law and constrained interface dilation was apparent as the pile experienced drained loading to failure, although with a lesser degree of radial expansion than with sands. Radial effective stresses were also found to fall with time after installation, leading to reductions in shaft capacity as proven by subsequent static tension testing. The jacked, closed-ended, piles’ ageing trends contrast sharply with those found with open piles driven at the same site, indicating that ageing is affected by pile tip geometry and (or) installation method.
Publication Date: 27-Sep-2018
Date of Acceptance: 5-Dec-2017
URI: http://hdl.handle.net/10044/1/55586
DOI: https://dx.doi.org/10.1139/cgj-2017-0145
ISSN: 0008-3674
Publisher: NRC Research Press
Start Page: 1577
End Page: 1591
Journal / Book Title: Canadian Geotechnical Journal
Volume: 55
Issue: 11
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Technology Strategy Board
Institution of Civil Engineers
Funder's Grant Number: EP/C528484/1
101968
1603
Copyright Statement: © Copyright 2018 – Canadian Science Publishing
Keywords: 0905 Civil Engineering
0907 Environmental Engineering
Geological & Geomatics Engineering
Publication Status: Published
Online Publication Date: 2018-09-27
Appears in Collections:Faculty of Engineering
Civil and Environmental Engineering
Geotechnics



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