Design curves of prefabricated vertical drains including smear and transition zones effects

Abstract The Hansbo theory considers the effect on the consolidation rate of Prefabricated Vertical Drains (PVDs) spacing, and the smear zone induced by PVDs installation process. However, it does not consider the effect of the transition zone between the smear zone and the undisturbed soil. In this paper the standard Hansbo radial consolidation theory has been modified and used as a basis for developing an improved design method for PVDs where the effect of a transition zone with hydraulic conductivity varying linearly with radius is included. The validity of the modified Hansbo theory was checked by comparing its results against those from finite element modelling; very good agreement was obtained. Based on the modified theory, a new simple PVD design chart was developed for situations where the PVD well resistance effect can be neglected (the usual case). The proposed design chart has the advantage of avoiding interpolation since the basic equations are very simple.

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