Numerical modelling of arching in piled embankments including the effects of reinforcement and subsoil

Zhuang, Yan (2009) Numerical modelling of arching in piled embankments including the effects of reinforcement and subsoil. PhD thesis, University of Nottingham.

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Abstract

Piled embankments provide an economic and effective solution to the problem of constructing embankments over soft soils. This method can reduce settlements, construction time and cost.

The performance of piled embankments relies upon the ability of the granular embankment material to arch over the ‘gaps’ between the pile caps. Geogrid or geotextile reinforcement at the base of the embankment is often used to promote this action, although its role in this respect is not completely understood.

Design methods which are routinely used in the UK (e.g. BS8006, 1995; Hewlett & Randolph, 1988; the ‘Guido’ method, 1987) estimate the stress which acts on the underlying soft ground completely independently of the properties of the soft ground. This stress is then generally used to design the amount of geogrid or geotextile reinforcement required. However, estimation of this load can vary quite considerably for the various methods.

Using finite element modelling the 2D and 3D arching mechanisms in the embankment granular fill has been studied. The results show that the ratio of the embankment height to the centre-to-centre pile spacing is a key parameter, and generic understanding of variation of the behaviour with embankment height has been improved.

These analyses are then extended to include single and multiple layers of reinforcement to establish the amount of vertical load which is carried and the resulting tension, both in 2D and 3D. The contribution to equilibrium of the subsoil beneath the embankment is also considered.

Finally the concept of an interaction diagram (and corresponding equation) for use in design is advanced based on the findings.

Item Type:Thesis (PhD)
Supervisors:Yu, H.-S.
Ellis, E.A.
Faculties/Schools:UK Campuses > Faculty of Engineering > Department of Civil Engineering
ID Code:891
Deposited By:Ms Yan Zhuang
Deposited On:26 Mar 2010 11:44
Last Modified:26 Mar 2010 11:44

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