RELATION BETWEEN THE PLASTICITY INDEX AND KEY CONSOLIDATION PARAMETERS OF SOFT GROUND STABILIZED BY VACUUM PRELOADING TOGETHER WITH VERTICAL DRAINS

This study addressed the relationship between the plasticity index (PI) and the key parameters of the vacuum consolidation process including the consolidation time (t), the degree of consolidation (U), and the thickness of the treated soft soil layer (H) when improving soft ground by vacuum preloading together with vertical drains. For this purpose, the coupled analysis technique which combines SEEP/W and SIGMA/W modules in Geostudio commercial software is applied for the simulation. Three different foundations corresponding to different soft soils in Dinh VuHai Phong, Duyen Hai – Tra Vinh, Nhon Trach – Dong Nai were considered. The suitability of the predicted numerical models was calibrated using experimental results of laboratory and field tests. The results show that it is possible to link the consolidation time of the foundation and PI by a linear relationship. Higher values of PI results in a longer consolidation time. This relationship is clearer when it comes to the foundation with a higher thickness of the treated soft ground. The results of this study, therefore, help technical workers to quickly give suitable predictions about the process of consolidation when applying the vacuum preloading method in soft soil treatment.