2D Numerical Modeling of a Constructed Geosynthetic-Reinforced Embankment over Deep Mixed Columns: Fid-Bau Portal

2D Numerical Modeling of a Constructed Geosynthetic-Reinforced Embankment over Deep Mixed Columns

Han, J. / Huang, J. / Porbaha, A.

Deep mixed (DM) columns have been commonly used to support embankments over soft soil. The inclusion of geosynthetic reinforcement over DM columns is intended to enhance load transfer from soil to columns, reduce total and differential settlements, and increase slope stability. As a result, it creates a more economical alternative. A constructed geosynthetic-reinforced embankment over DM columns at Hertsby, Finland was selected for the numerical modeling and analysis. This embankment was constructed to support roadways over very soft soil to approach a bridge. The DM columns were installed in a combination of wall and column types. A high strength woven geotextile was used above the DM columns to bridge over the soft soil between columns. Instrumentation was installed to monitor the settlements of the embankment and the strains in the geotextile over time. A finite difference method, incorporated in the FLAG (Fast Lagrangian Analysis of Continua) 2D software, was employed to model this embankment. In the numerical analysis, deep mixed columns were modeled as 2-D continuous walls. Cable elements with an allowable tensile strength and zero compression strength were used for representing the geotextile reinforcement. Embankment fill, soft soil, firm soil, and deep mixed walls were modeled as linearly elastic perfectly plastic materials with Mohr-Coulomb failure criteria. The embankment construction was simulated by six lifts. The computed settlements of the embankment and the strains in geotextile reinforcement compared reasonably well with the measured results. In addition, this paper presented the numerical results on stress distribution on the DM columns and the soft soil, the vertical displacement contours, and the distribution of tension along the reinforcement.