Nonlinear Consolidation Analysis of Stone Column Composite Foundations Considering Radial and Vertical Flows within the Stone Column and the Variation of Well Resistances

The clogging effect caused by installing stone columns is depth dependent. The movement of soil particles into the stone column, which is induced by the consolidation of soils, further resulting in a clogging effect on the stone column, causes the permeability of stone columns to decay temporally. Considering that the water inflows into the stone column from the soils around the column are not equal to the outflows from the stone column, a nonlinear consolidation model of stone column composite foundation with variable well resistance is established. The finite-difference method is adopted to obtain the solution for the proposed consolidation model, and the result is compared with the existing solutions under specific conditions to verify its reliability. Extensive computations are analyzed to investigate the effect of variable well resistance, stone column deformation, and radial flows within the stone column on the average degree of consolidation of stone column composite foundations, and the results show that the consolidation rate of the composite foundation under variable well resistance is significantly slower than that under constant well resistance. The effect of stone column deformation on the consolidation of composite foundations increases with an increase in the replacement ratio. Finally, the proposed consolidation model of stone column composite foundation is applied to the settlement calculation of an embankment in the Muar Plains, Malaysia. The theoretical result by the proposed model shows better agreement with the measured data than those by the existing solution, which indicates that the proposed consolidation model possesses a certain engineering practicability.