Abstract. Design and construction of earth embankments on soft formations encounters the problem of excessive total and differential settlements, large lateral displacement and inadequate bearing capacity of such formations. Preloading fills coupled with prefabricated vertical drains (PVD) is one of the soil improvement techniques exhibiting successful use in stabilizing soft clay formations. This study investigates, numerically, the performance of a monitored earth embankment that was constructed on a very soft to soft clay formation improved by PVD. Numerical analysis was carried out using the two-dimensional finite element program PLAXIS, considering the smear effect. A good comparison was revealed between the monitored and the predicted responses. In addition, a sensitivity study was carried out to highlight the influence of some modeling parameters and design considerations that may be of a major concern on designing such embankments. The considered parameters were the PVD length, the PVD spacing, the smear zone permeability and the soft clay characteristics.