Thesis-2008-Baxter.pdf (3.99 MB)
Innovation in the design of continuous flight auger and bored displacement piles
thesis
posted on 2009-08-05, 09:02 authored by David BaxterThe field of pile design and construction in the United Kingdom is currently in a period of
change. Not only are new processes and techniques being developed but also the legislative
landscape is changing with the introduction of new Europe wide normative standards (BSI,
2004, 2007).
This project sought to optimise pile design through better understanding and interpretation of
ground conditions and of the pile-soil interaction for two pile types, continuous flight auger
and bored displacement piles.
Quantitative methods for interpreting and summarising previous knowledge and experience
have been developed; the strata are divided into discrete bands and properties are represented
with summary statistics. Experience and previous knowledge relating to the shear strength of
London Clay have been quantified and presented using this approach. Furthermore, a
straightforward tool has been provided for the implementation of such data into design; the
previous knowledge and new site specific data are combined using Bayesian updating.
Through use of this technique, the uncertainty associated with interpreting ground conditions
from site data has been demonstrated to be reduced. The techniques described have been
adopted into design practice within the sponsoring company.
Bored displacement piles are a relatively new pile type. There is little published data or
scientific understanding of the processes undergone by the soils during and after construction
and the effect that these have on pile performance. This research identified the need for, and
developed, a unified framework of descriptors for the various types of bored displacement
pile and investigated the installation energy and performance of bored displacement piles in
London Clay. The energy to construct the pile was observed to be highly variable and not
directly related to capacity. Performance of bored displacement piles was observed to be
similar to continuous flight auger piles of similar dimensions; typical values for the adhesion
between bored displacement piles and the surrounding soil were established and these were
comparable to those achieved by continuous flight auger piles.In addition, to enable the analysis of the probability of failure of a pile, the sources of
variation have been investigated and the variability quantified. Besides the soil conditions, the
dimensions of the pile, notably pile diameter, were found to be a significant source of
variation.
History
School
- Architecture, Building and Civil Engineering
Research Unit
- Centre for Innovative and Collaborative Engineering (CICE)
Publisher
© David James BaxterPublication date
2009Notes
A dissertation thesis submitted in partial fulfilment of the requirements for the award of the degree Doctor of Engineering (EngD), at Loughborough University.ISBN
9780947974879Language
- en
Qualification name
- EngD
Qualification level
- Doctoral
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