Theoretical and numerical perspectives on performance of stone-column-improved soft ground with reference to transport infrastructure

In this chapter, an axisymmetric solution is presented to study the performance of soft ground reinforced with stone columns with special emphasis on transport infrastructure. For typical surcharge (embankment) loading, significant column-to-soil stiffness ratio and the flexible nature of the embankment initiate the fill weight to "arch over" the stone columns, imposing uneven load distribution on the surface. In addition to the arching effect, the numerical model captured the influence of smear and clogging on the consolidation characteristics of soft clay. To simulate the field condition relevant to transport corridors, a free strain hypothesis was adopted. The entire numerical analysis was performed by means of finite difference technique with composite central and forward difference methods applied on axisymmetric soft soil elements under K0-condition. The model was validated by comparing with existing solutions and available field test results. Using the solutions developed, a design recommendation with relevant curves was proposed. The model and the design curves are successfully applied to selected case studies with several important conclusions.