Numerical modelling of stone columns beneath a rigid footing

This paper presents a set of systematic 2D and 3D finite element analyses that study the performance of groups of stone columns beneath a rigid footing. Those numerical analyses show that the number of columns and their arrangement have a small influence on the load-settlement curves. Furthermore, a reanalysis of previous laboratory data available in the literature confirms the small influence of the column configuration. That finding provides some background for homogenisation techniques and validates the use of equivalent gravel trenches. This paper proposes a new simplified approach to study groups of stone columns, which involves converting all the columns of the group beneath the footing in just one central column with an equivalent area. This simplified model is used to conclude that, for settlement reduction, there is a column critical length in a homogeneous soil around twice the footing width, and high area replacement ratios beneath a rigid footing are less efficient.