Multilayered low-strength geogrid-reinforced piled embankment

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.