Numerical Analysis of the Settlement Behavior of Soft Soil Improved with Stone Columns

The use of column-like elements for improving both the settlement performance and bearing capacity of foundations constructed over soft soils is well understood for large groups of columns supporting an infinitely wide load, such as embankments and slabs. However, little is still understood for lightly loaded, low-rise structures supported by pad foundations constructed on a finite number of stone columns, particularly when a crust layer is present at the top of the soft soil. In this study, a comprehensive 3D finite element analysis is used to investigate the influence of key design parameters, such as column spacing, column length, footing shape, and the presence of a crust layer, on the settlement behavior of stone columns to support shallow foundations. The results show that the modeling of a well-characterized soft soil profile predicts well the long-term settlement using both drained and undrained analyses. It was found that the presence of a stiff crust layer has a significant influence on the deformational mode of the stone columns which is not captured by laboratory modeling.