Vacuum preloading and PVDs in soft soils beneath embankments: 3D coupled analysis incorporating overall stability study

Abstract

Although embankments on soft soils with prefabricated vertical drains (PVDs) under vacuum preloading have been widely studied, there is a lack of studies in the literature in which overall stability is analysed through three-dimensional (3D) mechanical-hydraulic coupled modelling. In order to contribute to overcome such deficiency, this paper presents 3D numerical analyses of an embankment on soft soils incorporating PVDs and vacuum preloading. A finite element code, which includes 3D fully coupled analysis, is used and a method for overall stability study – which uses the 3D numerical results obtained with the finite element code – is presented and applied. A parametric study is performed in order to analyse the influence of the magnitude of the vacuum preload and the staged construction of the embankment (time of vacuum application before completion of the embankment). Overall stability, excess pore pressures, settlements, horizontal displacements and stress levels are analysed.