Consolidation of Ground with Partially Penetrated PVDs Combined with Vacuum Preloading

Partially penetrating prefabricated vertical drain (PVDs) with a combined surcharge and vacuum preloading are considered in this paper. The analysis results can be used in cases where the soft soil clay is too deep and not economical to be penetrated to full depth, or the surcharge preloading is too small to justify full penetration of soft clay layer or the vacuum pressure can be lost, which is caused by the permeability of the bottom of the clay for the fully penetrated drain etc. In this model, a virtual vertical drain is assumed to reflect the real three-dimensional seepage in the soil beneath the tip of PVD instead of using the traditional one-dimensional consolidation theory, and at the same time, the well-resistance and the smear zone can be also considered. The vacuum pressure distribution is assumed to be no loss along the drain, whereas a zero pore pressure boundary condition is assumed at the interface between the bottom clay layer and the lower drainage layer. The proposed solutions are then employed to analyze a case history.