Piled embankments provide a useful method for constructing
embankments on soft foundations where the full control of surface
movements is crucial. The optimisation of the solution requires
a
detailed understanding of the arching mechanisms in the fill as
well
as the behaviour of the foundation and reinforcing materials.
Our foundations and geotechnics team have considerable expertise in
the analysis and design of piled embankments. We have particularly
gained experience from applied research and design for
construction.
Applied research
Mott MacDonald undertook a series of research projects for the
company Terram from 1994 to 1999. We investigated the fundamental
behaviour of piled embankments. The interaction of the fill
material, the geosynthetic reinforcement and the foundation
material were assessed using three-dimensional numerical
analysis.
Our research allowed for a design method to be developed accounting
for all relevant aspects. The design method can be used to produce
a piled embankment design which is compatible with the BS8006
philosophy but provides a more economic and accurate solution.
Designs using this method ensure that the reinforcement is
optimally positioned.
The design method has been validated against both numerical
analyses, a published case history and a trial piled embankment. If
required, designs produced using the method can be quickly
confirmed using numerical methods.
Design and construction
We have carried out a number of piled embankment designs over the
past three years. During the research period we acted as designers
for a range of embankments for companies such as Maccaferri and
Terram.
Mott MacDonald's designs have also been carried out for the
Doncaster North Relief Road and the new Guinness Development in
London. In both cases the design was optimised to ensure that total
service requirements were met. We also provide construction
specifications and support during the construction process.
The design method has been extended for the A63
Selby bypass in the UK, to combine staged construction with the
piled embankment solution for a more optimised design.
Further information is available in the following
publications:
- “A numerical investigation of the behaviour of piled
embankments”. Ground Engineering, November 1997, Russell, D and
Pierpoint, ND
- “Two-and three-dimensional numerical analysis of the
performance of piled embankments”. Sixth International
Conference on Geosynthetics,Georgia, USA, March 1998. Kempton, G,
Russell, D, Pierpoint, N D and Jones, CJFP
