Finite-Element Analysis on the Effect of Subsoil in Reinforced Piled Embankments and Comparison with Theoretical Method Predictions

Abstract

This paper presents a finite-element (FE) analysis of the effect of subsoil in a reinforced piled embankment and compares the findings with predictions from a theoretical method. It shows that the subsoil can carry as much as 75% arching embankment load for the present standard model (pile spacing of 2.5 m, geogrid stiffness of 6 MN/m, embankment height of 6 m, and subsoil compression index of 0.7). Also, the proportion is much larger for the lower value of pile spacing, geogrid stiffness, embankment height, and subsoil compression index. The maximum settlement of subsoil is found to be more sensitive to the pile spacing than to the geogrid stiffness. The theoretical method shows reasonable agreement with the FE results and can therefore be used to predict the effect of subsoil in reinforced piled embankments. The geogrid has a significant role in carrying the entire embankment load without the subsoil support. However, this effect may lead to intolerable geogrid strain due to relatively large settlement. Two case studies are assessed by the theoretical method. They show that stiff subsoil can carry a significant portion of the embankment load, whereas very soft subsoil support may result in intolerable strain on the geogrid. The effect of the subsoil, therefore, should be considered in the design.