Geogrid-Reinforced Pile-Supported Railway Embankments: A Three-Dimensional Numerical Analysis (05-0216)
Jie Han, University of Kansas
Jie Huang, The University of Kansas
James G. Collin, Collin Group, Ltd.

Piles or columns have been successfully used in combination with geosynthetics to support embankments over soft soil. The inclusion of geosynthetic reinforcement over piles is to enhance load transfer from soil to piles, reduce total and differential settlements, and increase slope stability. As a result, it creates a more economical alternative than that without the geosynthetic. A constructed geosynthetic-reinforced pile-supported embankment in Berlin, Germany was selected for numerical modeling and analysis. This embankment was constructed to support railways over deep deposits of peat and soft organic soils. Precast piles and caps were installed with a load transfer platform formed by three layers of geogrid and granular materials installed between the piles and the embankment fill. Instrumentation was installed to monitor the settlements of the embankment and the strains in the geogrid layers over time. A finite difference method, incorporated in the FLAC (Fast Lagrangian Analysis of Continua) 3D software, was employed to model this embankment. In the numerical analysis, piles were modeled using pile elements and caps were model as an elastic material. Geogrid elements built in the software were used for representing the geogrid reinforcement. Embankment fill, soft soil, firm soil, and platform fill material were modeled as linearly elastic perfectly plastic materials with Mohr-Coulomb failure criteria. The embankment was built by a number of lifts to simulate its construction. This paper presents numerical results and comparisons with field measurements on the vertical and lateral displacements, the tension along the reinforcement, and the axial forces and moments on piles.