Numerical modelling of stone columns in soft clay under an embankment

A series of numerical calculations have been performed to investigate the behaviour of floating stone columns in soft clay under an embankment at working load level. Three different approaches are studied using finite element calculations with 2D and 3D idealisations. Challenges in numerical modelling of stone columns include estimation of the effect of smear around stone columns, and consideration of construction effects due to stone column installation. Conversion of the 2D numerical model from a stone column grid into a 2D stone trench structure, demands that an adjustment is made to the soil parameters within the column grid. One objective is to establish whether the response of an embankment on stone columns can be modelled in 2D with less computational effort compared to a full 3D analysis. The results from geotechnical centrifuge tests of an embankment on soft clay improved with floating stone columns provide the basis for this numerical comparison. The main characteristics of the embankment deformation and the development of pore water pressures within the column grid give an indication about the quality of the numerical models investigated.