Performance of Composite PVD–SC Column Foundation under Embankment through Plane-Strain Numerical Analysis

Abstract

The combination of soil–cement (SC) columns and prefabricated vertical drains (PVDs) has indicated great success in improving ground stabilization in recent years; however, there is a lack of proper plane-strain numerical modeling to detail the role of PVDs in improving the performance of the SC column method. This study thus presents a numerical analysis of soft soil ground improved by the coupled PVD–SC column method based on a proposed equivalent plane-strain model considering the combined effects of PVDs and SC columns in the ground. The model is verified by applying it to a test embankment where long PVDs were installed in soft soil in combination with floating SC columns. To investigate the role of PVDs in the composite foundation, the numerical analysis is then conducted for two cases, with and without PVDs. The effects of discharge capacity of PVDs on the SC column behavior are also examined. The results show that the PVDs significantly improve performance of the composite foundation as they considerably reduce both postconstruction settlement and lateral displacement, while increasing the efficiency of soil arching and the bending moment capacity in SC columns. The numerical results obtained from the proposed model are in good agreement with the field data. The current study also shows that the discharge capacity of PVDs should be larger than 20 m3/year to enhance the positive influence of PVDs on the entire performance of the composite foundation.