Encased stone columns: coupled continuum – discrete modelling and observations

The present research focuses on the simulation of encased stone columns in a 2D state by utilising the coupled finite difference method (FDM) and discrete element method (DEM). The stone column material was modelled by DEM using irregularly shaped particles, and the geotextile used as the encasement of the stone column was simulated using parallel-bonded particles. The surrounding clayey soil was modelled by FDM. Two models were combined by employing a direct coupling method. After validating the coupled DEM-FDM model through comparisons with experimental results, the encased stone column was investigated at the micro and macro scale. The results indicated that the coupled model can imitate the behaviour of the encased stone column to a reasonable degree. Furthermore, the encased stone column exhibited different deformation behaviour than the ordinary stone column. The use of the encasement decreased the stress deviation at the top and bottom of the column. Also, the soil surrounding the encased stone column displayed different displacement behaviour than the soil surrounding the ordinary stone column. In addition, the effect of encasement length on stone column responses was examined.