Effectiveness of Stone and Deep Mixing Lime Columns on Stability of Embankments Constructed on Soft Consolidating Soil

One of the most common, effective and innovative ways to improve soft soil is to use stone columns or lime columns. An extensive study has been conducted to find the effectiveness of lime or stone columns to improve the settlement of embankments constructed over soft consolidating soil. There are very few studies to evaluate the effects of columns on embankment safety factor during foundation soil consolidation. This study examined the effectiveness of stone and lime columns on the embankment stability, both in terms of safety factor and settlement, which are determined at different intervals of time, during the foundation soil consolidation. Further, it was also investigated the effectiveness of stone and lime column composite system. In this numerical study, two-dimensional plane strain finite element method is used. This study shows that, stone columns are more effective than lime columns in reducing post-construction settlement and to accelerate consolidation process, whereas lime columns are observed to be more effective than stone columns in improving the safety factor after the embankment construction indicating that the usage of stone or lime columns is significantly affected by the purpose for which columns are used. In addition, it is also observed that the column effectiveness on safety factor is strongly influenced by the relative shear strength of embankment and foundation soils. Further, provision of stone and lime columns as a composite system performs better than providing only stone or lime columns.