Comparison Analysis On Behavior Of Geosynthetic Reinforcement In Piled Embankments Under Plane Strain And Three-Dimensional Conditions: Numerical Study

In the system of Geosynthetic-Reinforced Pile-Supported (GRPS) embankment, geosynthetic reinforcement contributes to load transfer from surrounding soil to pile through tensioned membrane effect. Among the design methods of GRPS embankments, tension in geosynthetic reinforcement were mostly developed based on a plane strain (2-D) condition or a strip between two supports. However, piles are typically installed in a square or triangular pattern in practice. It has not been quite clear whether the calculated tension in a 2-D model can represent the real 3-D condition well or not. In this paper, plane strain and three-dimensional numerical analyses were conducted to investigate the behavior of geosynthetic reinforcement in 2-D and 3-D conditions. Pile caps were simplified as square rigid stationary parts arranged in a square or triangular pattern and the surrounding soil between the piles were modeled using modulus of subgrade reaction. Geosynthetic reinforcement was modeled using an orthotropic shell element. The results show that the maximum tension and the sag in the geosynthetic reinforcement were smaller in the models with pile cap in a triangular pattern than those in the models with pile cap in a square pattern. The maximum strains in the geosynthetic reinforcement in a 3-D condition were larger than those in a 2-D condition. A series of conversion factor were proposed to correct the maximum tension in geosynthetic reinforcement in a 2-D condition to that in a 3-D condition considering the pile cap shape and arrangement, and the surrounding soil support.