Three-dimensional finite-element analysis of arching in a piled embankment

Abstract

Piled embankments rely upon arching of the embankment material onto underlying piles, thus potentially significantly reducing load on the soft subsoil that more generally prevails beneath the embankment. Finite-element modelling of a piled embankment in plane strain has previously been reported; the ‘subsoil' was not explicitly modelled, but was represented by a vertical stress acting on the underside of the embankment. This technical note considers extension of this work to three dimensions. The results make particular reference to prediction of the stress on the subsoil at the point of ‘maximum arching' and the height of influence of arching within the embankment.

Multilayered low-strength geogrid-reinforced piled embankment

“…The 's G ' line (dotted line) in Figures 6(a) and 6(b) shows the uniform value of embankment arching stress of 18 kPa, obtained in the same way as Zhuang et al (2012). In order to obtain the s G , an FE model presented by Zhuang et al (2012) is developed, which is again the 3D column model without the pile and subsoil.…”

“…Figure 2 shows the finite-element (FE) mesh used in the analysis, together with the location of the geogrids for both three-layer and single-layer geogrid models. Due to symmetry, only one-quarter of the pile and its tributary area is modelled Ellis, 2014, 2016;Zhuang et al, 2012). Thus, a 'unit cell' with square dimensions of half the pile spacing is used in the analyses, which are carried out using the FE package Abaqus (version 6.12).…”

“…s G can be based on the 'ground reaction curve' (GRC) concept proposed by Iglesia et al (1999) for arching over underground structures. Based on the 3D FEM of the embankment arching for uniform subsoil support, Zhuang et al (2012) reported that the minimum stress (s G,min ) is reached when d was less than 4% of the clear spacing between pile caps (s − a), and prior to the minimum, s G initially reduces very rapidly with d. It is assumed that s G = s G,min , where the value can potentially be derived Multilayered low-strength geogrid-reinforced piled embankment Wang, Zhuang, Liu and Xiao from a wide range of methods (e.g. as compared by Ellis and Aslam (2009)), assuming that the embankment is sufficiently high for arching to occur (e.g.…”

“…as compared by Ellis and Aslam (2009)), assuming that the embankment is sufficiently high for arching to occur (e.g. Zhuang et al, 2012). s G will be determined based on the FEM for the embankment supported by a uniform subsoil stress, as reported by Zhuang et al (2012).…”

“…Zhuang et al, 2012). s G will be determined based on the FEM for the embankment supported by a uniform subsoil stress, as reported by Zhuang et al (2012). Figure 6 shows the results of vertical stress carried by the subsoil (s s ) and the geogrid (s r ) along the horizontal line BC (Figure 2) at the edge of the FE mesh and the diagonal BA.…”