Numerical Study of the Variation of the Voids Ratio of Soil Improved Stone Column

This research work is part of the trend of soil reinforcement procedures aimed at improving poor quality soils. Among these techniques, those that use stone columns. Although the aspects concerning the construction processes are now well mastered, the design methods of these reinforced soils remain to be developed. A numerical simulation presented to study two unit cell models. The 3D proposed simulation model is subjected to gravity and a static load. The first model presents a unit cell composed of stone column in the center and a surrounding clay soil volume. The second is converted into an equivalent unit cell (the volume averaging) in terms of physical and mechanical parameters of a composite material (equivalent parameters). Under the effect of incrementally loading-unloading applied to these unit cell models, voids ratio variations and stress path evolution are analyzed. The results indicate that applying a load to an equivalent unit cell can affect the void ratio-volumetric deformation curves and increase settlement. The void ratio and the corresponding volumetric deformation decreased by comparing the equivalent homogenized model with the non-homogenized model. The results show that the void ratio decreases by about 10% on average, but the volumetric strain decreases by 80%. Therefore, the stress path corresponding to the decrease of the average effective stress by 1% increases the deviatoric stress on average by 10%. Diagrams obtained by numerical results are in accordance with the results derived from experimental observations. The adopted technique can substantially can describe sufficiently the influence of the equivalents physical and mechanical parameters on the improvement in the soil of unit cell.