Multiphase constitutive model for the design of piled-embankments: Comparison with three-dimensional numerical simulations

This contribution presents a so-called "multiphase" model for soft grounds improved by rigid vertical piles, aimed at capturing the global constitutive behavior of the reinforced ground. A special emphasis is put on the soil-inclusions interaction phenomena, which play a decisive role in the way the applied loads are transferred to the inclusions, and thus clearly affect the performance of the reinforcement scheme in terms of settlement reduction. It is shown in particular how the identification of appropriate coefficients, relating to the lateral as well as pile head interactions, performed from numerical simulations on a simple reference configuration, makes it possible to implement such a model in a linear elasticity-based finite-element simulation. The so-obtained numerical code is then applied to the settlement analysis of an embankment and the correlative reduction of this settlement which could be expected from the incorporation of rigid piles into the soft ground layer. The results derived from this simulation are favorably compared with those obtained from a direct and thus considerably more computational time consuming, three-dimensional simulation.