An isotach approach for considering the rate-dependent axial loading behaviour of open steel piles driven in chalk
File(s)
Accepted version
Author(s)
Wen, Kai
Jardine, Richard
Kontoe, Stavroula
Liu, Tingfa
Type
Journal Article
Abstract
This paper analyses the effects of loading rate on the axial shaft capacity and stiffness for piles driven in the low-to-medium density chalk, taking advantage of a series of field Maintained Load (ML) tests. As with sands and clays, piles’ axial loading behaviour in chalk is significantly time and rate dependent once a ‘creep-yield’ load is exceeded, which typically corresponds to approximately 1/3rd of the piles’ shaft capacity. An isotach approach was employed to derive families of load-displacement curves for a range of constant displacement rates from the loading and creep stages of ML axial pile tests, while recognising a long-term load-displacement relationship that acts as a lower bound to the field behaviour. A framework was developed for adjusting the load-displacement behaviour to account for rate effects, in which empirical load modifiers are applied that depend on loading levels and pile head displacement rates. Overall, the impact of loading rate amounts to an increase of load of around 7.0% axial shaft resistance per log cycle of displacement rate over the ranges applied in typical tests. These findings aid the assessment of rate effects when analysing site tests on piles driven in chalk and designing the foundations to cope with a wide range of both extreme short-term events and longer-term maintained loading cases.
Date Issued
2025-10-01
Date Acceptance
2025-03-18
Citation
International Journal of Geomechanics, 2025, 25 (10)
ISSN
1532-3641
Publisher
American Society of Civil Engineers
Journal / Book Title
International Journal of Geomechanics
Volume
25
Issue
10
Copyright Statement
Copyright © © 2025 American Society of Civil Engineers. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Publication Status
Published
Date Publish Online
2025-07-24