Numerical modeling of embankment on soft ground improved by prefabricated vertical drains and deep cement mixing columns

Recently, prefabricated vertical drains (PVDs) and deep cement mixing (DCM) columns have been combined to improve the soft soil ground under embankment. This not only significantly improves the shear strength in soft soil ground but also increases the rate of consolidation. The present study develops a simple two-dimensional (2-D) plane-strain numerical model of the DCM columns and PVDs improved soft ground under embankment. The geometry of the PVD and DCM column in equivalent 2-D model were obtained from the concept of same area replacement ratio, while the equivalent horizontal permeability of soft soil and DCM columns surrounding PVD was deduced from the matching of the total volume of water to be discharged in an axisymmetric model and the total changes in flow in a plane strain. Subsequently, the proposed method was applied to the Huai-Yan embankment in China, in which was used the combined method for ground improvement. The results of settlement and lateral displacement obtained from the proposed model were in good agreement with the observed data and results obtained from previous solution.