Finite Element Modeling of Vacuum Consolidation

Abstract

Vacuum consolidation is a method used for preloading and consolidating soft and very soft saturated fine-grained soils. The procedure consists of installing vertical and horizontal vacuum transmission pipes under an airtight impervious membrane and evacuating the air below the membrane producing an atmospheric pressure on the soil. This article aims at presenting the set-up and the results of a finite element analysis performed for a reclamation project in Vietnam. In this context the two-dimensional behaviour of an embankment on soft soils incorporating prefabricated vertical drains is analyzed with the geotechnical finite element package PLAXIS 2D. This FE analysis is carried out in the framework of a fully coupled flow-stress analysis with unsaturated soil condition. For this purpose, a new drain element has been implemented on which negative pore pressure (vacuum induced suction) can be applied as a flow boundary condition. Advanced constitutive modelling for the nonlinear behavior of the constitutive soft soil layers is also considered.