In recent civil engineering project, many projects have currently been carried out on soft grounds that were considered as inappropriate sites for construction purposes. However, constructions on soft soils are challenging works because of their poor properties such as low shear strength, high compressibility and unfavorable permeability.
In order to overcome these problems, a variety of ground improvement techniques have been employed. Recently, the use of prefabricated vertical drains (PVDs) with vacuum application has gained a popularity for ground improvement where the construction of high embankment for preloading is not available. The conventional vacuum consolidation system is composed of an impervious membrane and a cut-off wall to maintain a vacuum pressure during the whole treatment process. It has been reported that there exist several problems in using the impervious membrane and the cut-off wall. They can be easily damaged during construction and thereby resulting in a poor control of vacuum pressure. To overcome these shortcomings, a new vacuum consolidation system, which is called as an individual vacuum consolidation method, has been developed.
However, it is not an easy work to design the individual vacuum consolidation method due to several limitations of the consolidation theory. The numerical analysis can often be used as an alternative method to predict the consolidation behavior of soft ground to be treated with the vacuum consolidation method.
In this study, numerical simulations were performed to simulate the individual vacuum consolidation system using the finite element program, Plaxis 2D. The modelling procedures of the vacuum consolidation system are presented in detail with results of an unit-cell analysis. In addition, a case study was carried out to assess the applicability of the Plaxis 2D for simulating the consolidation behavior of soft ground subjected to the individual vacuum pressure.

Keywords : Ground improvement techniques, Individual vacuum consolidation method, Numerical analysis, Plaxis 2D