The composite foundation of prefabricated vertical drains (PVDs) and soil-cement (SC) columns has shown considerable advantages by effectively combining drainage facilitation with the high bearing capacity. Past studies employed the finite element method (FEM) to simulate the coupled effect of PVD-SC columns foundation, but they often ignore the variation in column and soil stiffness over time. This study reassesses the interaction between vertical drains and soil-cement column and the corresponding consolidation process while considering the development in stiffness of SC columns. A 3D FEM modelling is implemented with reference to a past case study where PVD-SC columns composite solution was applied to improve soft soil. The stiffness modulus of cement-treated soil is increased over time (first 120 days), and the results of settlement, excess pore water pressure and stress distribution are investigated. The simulation is validated against field data and past numerical studies. The results show that increasing stiffness of SC columns over time can significantly affect the stress distribution and arching effect, however, it does not clearly influence consolidation progress. This suggests that using constant stiffness for SC columns might be acceptable to simplify practical consolidation modelling.