Finite Element Modeling of Embankment Resting on Soft Ground Stabilized with Prefabricated Vertical Drains

Abstract

This paper presents the numerical modelling of embankment resting on soft soil improved by the use of prefabricated vertical drains (PVDs). The study has been validated with the field measurements of settlements and excess pore pressures for a trial embankment at the Krishnapatnam Ultra Mega Power Project (KUMPP) in Nellore, Andhra Pradesh, India. The paper elaborately highlights the intricate effect of various parameters such as the drain spacing, reduction of permeability due to smear, and the efficiency of floating drains. Two-dimensional finite element modelling was carried out using PLAXIS 2D. In the analysis, classical axisymmetric solution for consolidation by vertical drains has been converted into an equivalent two-dimensional plane strain analysis. The comparatives reflect the agreements and differences between the field measurements and the results obtained from the numerical model. Based on the results, the state of smear prevailing in the field has been identified. The numerical study suggests that the optimal length of the partially penetrating drains (75-80% of the full penetration) would be efficient in aiding sufficient vertical consolidation of the soft soil site, thus making its usage more economical.