Multilayered low-strength geogrid-reinforced piled embankment

Kangyu Wang,Henglin Xiao,Hanlong Liu,Yan Zhuang

doi:10.1680/jgere.18.00001

Kangyu Wang, Henglin Xiao + Show 2 more

Open Access

https://doi.org/10.1680/jgere.18.00001

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Abstract

Multilayered low-stiffness geogrids have been used in constructing embankments, but without full understanding of their true behaviour – for example, the construction of apartments in Northern Ireland failed due to the excessive and continuing deformation of the load transfer platform. This paper presents a numerical simulation of multilayered geogrid-reinforced piled embankments. It shows that the inclusion of geogrids can effectively help transferring stress from subsoil to the pile cap, particularly for stiffer geogrids. Although the maximum settlement is approximately identical, an embankment with a three-layer geogrid provides more uniform stress distribution on the surface of subsoil and results in less differential settlement through the embankment. The maximum settlement and the total tension in the geogrid are found to be dependent only on the total stiffness provided and not on the number of geogrid layers. The parametric study shows that the combination of very soft subsoil and a geogrid with low stiffness results in relatively large settlement and may cause intolerable geogrid strain. The pile spacing is also found to be the most sensitive factor influencing the maximum settlement of the subsoil. Finally, an analytical method is assessed and shows reasonable agreement with the numerical results.

Highlights

Significantly increased traffic volumes have led to increased construction of highways and railways all over the world
Due to the complexity of the reinforced piled embankments, some of these methods are based on a wide range of conservative assumptions that give rise to conflicting results, with respect to the degree of the load transfer and stress–strain developed in the geogrid (Abdullah and Edil 2007; Chen et al, 2010; Russell and Pierpoint, 1997; Stewart and Filz, 2005; Zhuang and Wang, 2015)
This paper presents a comprehensive investigation on the multiple layers of low-strength geogrid-reinforced piled embankment; the results are compared with those for an embankment with a single-layer geogrid and one with no geogrid reinforcement

Summary

Introduction

Significantly increased traffic volumes have led to increased construction of highways and railways all over the world. The majority of the vertical stress is transferred from the subsoil to the pile cap and increases the soil arching effect with the increase in the geogrid stiffness, particulary when the geogrid stiffness is relatively low. Assuming that the tensile reinforcement corresponds to a uniform vertical load and deforms as a parabola, the vertical stress carried by the geogrid (sr) and the maximum settlement of geogrid (dr) can be obtained based on following equation (Zhuang et al, 2014). It can be concluded that the maximum settlement of the geogrid is more sensitive to the pile spacing compared to the geogrid stiffness

Conclusions

Findings

90 Single layer