The study of the effect of the rigid column on soil improvement

In this study, the behaviour of embankment or foundation on soft clays imroved with rigid column, such as stone, deep soil mixing and jet grout columns, were investigated by using numerical method. The effect of different design parameters (such as depth replacement ratio, area replacement ratio and column stiffness) on the composite foundation system were studied in the analyses. The numerical analyses have been performed by using PLAXIS computer software based on finite element method. The time dependent behavior of a test embankment on soft clay reinforced with deep mixing columns reported in the literature was analysed to verify the numerical results. Then, a parametric study was conducted to evaluate the influence of column rigidty and permeability on the composite foundation system. Finally, the predicted results indicate that the columns not only reduced the total settlement but also accelerated settlement time of the clay under the embankment loading, due to the much higher stiffness of the column material. The results show that more economical, faster and easier methods can be achieved when the behaviour of an embankment or a foundation on soft clays improved with rigid columns were accurately predicted in the numerical analyses. Keywords: Rigid column, Floating rigid column, Deep mixing column, Stone column, Jet grout column.