Numerical Simulation of Embankment Construction on Soft Soil: A Case

Constructing on soft soil deposits is a geotechnical challenge, both in estimating soil settlements and in predicting shear strength. This study consists of a numerical simulation of the execution of a large and asymmetric embankment on soft soil constructed in stages, with prefabricated vertical drains (PVD) and wait phases, as well as a comparison of the prediction results with field measurements. The purpose is to adopt an equivalent two-dimensional model of an embankment to evaluate the stress–strain response in relation to the field measurements as an alternative way to the complex, three dimensional and heterogeneous real embankment problem. Thus, an in-house finite element (FE) program was used considering the hydromechanical coupling and the Modified Cam-Clay constitutive model, for the soft layers. For the numerical modeling, the embankment construction was performed in stages, following the executive design, and the plane strain analysis was performed with induced drainage in the soft soil layers. Due to the large number of PVD installed, a different approach was considered performing the numerical calculation of the equivalent permeabilities of these layers using an embedded discontinuity in regular FE mesh to represent each drain element. The estimated results of the numerical modeling and monitoring data showed that the lowest relative error found for settling was 2.57% and that the lateral movement, near the embankment, remained within in the range of measured values at a given assessed depth. The simulation data were consistent, however, that there was a need for more penetration testing to produce more adequate data and numerical model which can lead to realistic predictions.