Effective stress regime around a jacked steel pile during installation, ageing and load testing in chalk
File(s)Buckley et al (2018) accepted version.pdf (1.03 MB)
Accepted version
Author(s)
Buckley, Roisin
Jardine, Richard
Kontoe, Stravroula
Lehane, Barry
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.
Date Issued
2018-09-27
Date Acceptance
2017-12-05
Citation
Canadian Geotechnical Journal, 2018, 55 (11), pp.1577-1591
ISSN
0008-3674
Publisher
NRC Research Press
Start Page
1577
End Page
1591
Journal / Book Title
Canadian Geotechnical Journal
Volume
55
Issue
11
Copyright Statement
© Copyright 2018 – Canadian Science Publishing
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Technology Strategy Board
Institution of Civil Engineers
Identifier
https://www.nrcresearchpress.com/doi/10.1139/cgj-2017-0145
Grant Number
EP/C528484/1
101968
1603
Subjects
Science & Technology
Technology
Physical Sciences
Engineering, Geological
Geosciences, Multidisciplinary
Engineering
Geology
chalk
piles
shaft capacity
time effects
effective stresses
DISPLACEMENT PILES
SHEAR APPARATUS
SHAFT FRICTION
SAND
PENETRATION
DRIVEN
INTERFACE
STRENGTH
FOUNDATIONS
CLAY
Geological & Geomatics Engineering
0905 Civil Engineering
0907 Environmental Engineering
Publication Status
Published
Date Publish Online
2018-09-27