Three-Dimensional Numerical Analysis of Embankment Overlying Geotextile-Encased Columns with Granular Platform

A set of three dimensional-3D-finite element analyses was conducted to investigate the influence of the geogrid-reinforced granular platform on the behavior of embankment resting on geotextile-encased columns. The numerical analyses were performed using unit cell and strip configurations owing to verify the applicability and limitations of each model. The predicted results were initially validated with the data provided by field instrumentation and parametric analyses were then carried out by varying thickness of granular platform, stiffness of both basal geogrid and geotextile encasement. Results showed that the compacted granular platform may considerably affect the settlement and vertical stress distribution under the embankment. Both the vertical and horizontal deformations significantly reduced as thickness of the granular working platform increased. A shallow granular platform layer caused the tensile forces mobilized in the basal geogrid to increase as well as the stress concentration on the top of the encased columns. It was also found that the influence of the basal geogrid on soil horizontal deformation was highly associated to the thickness of the granular platform placed over soft clay layer.