Sidewalls and PVDs below embankments on soft soils - three-dimensional analysis by FEM

The sidewall technique (steel sheet pile or reinforced concrete walls, typically) - combined or not with prefabricated vertical drains (PVDs) - is a technique that minimizes the lateral deformation and upward displacement in the surrounding ground of embankments on soft soils, as well as increasing the overall stability of the structures. Although there is a large number of studies in the literature involving PVDs, there is a lack of studies regarding the sidewall solution, especially involving three-dimensional analysis. In order to overcome this deficiency, a computer code based on the finite element method (FEM) is used to analyse the three-dimensional behaviour of an embankment on soft soil incorporating sidewalls and PVDs. The same embankment, but without the vertical drains, is also modelled and compared with the case of PVDs. In addition, a parametric study is performed to evaluate the influence of the bending stiffness of the wall on the behaviour of the embankment. The computer code incorporates fully mechanical-hydraulic coupled analysis with the soil constitutive relations simulated by the p-q-theta critical state model.