Numerical Analysis of Geosynthetic-Rammed Aggregate Pier Supported Embankments

This paper presents results from numerical study to investigate the interactions between rammed aggregate piers and geosynthetic reinforcement in pier-supported embankments. The investigation was conducted using a two-dimensional, plane-strain, finite element model. Linear elastic, perfectly plastic constitutive model parameters were assumed for the rammed aggregate piers, the matrix soil, the embankment fill, and the aggregate blanket. In addition to several pier-soil stiffness ratios considered in the analyses, a range of center-to-center spacings between piers was included. The geosynthetic reinforcement was modeled as a tensile element with various tensile stiffness values. Results obtained from this study provide insight into: (1) the interaction between the pier elements and the geosynthetic reinforcement to reduce differential settlement; (2) range of stress concentration ratio; and (3) tensile force developed in the geosynthetic reinforcement. It is concluded that the efficiency of using geosynthetic reinforcement is improved as both the geosynthetic modulus and the pier-soil stiffness ratio increase.