Abstract:

By incorporating the logarithm models of e-lgσ and e-lgk of soil, the characteristics of the nonlinear increase in the soil’s compressive modulus and the nonlinear decrease in the soil’s permeability during consolidation were considered. Based on the above characteristics, an analytical solution was developed for the consolidation of stone column reinforced composite ground. The nonlinear consolidation behavior of composite ground was analyzed and the results show: the average degree of consolidation (ADC) in terms of stress is not equal to that in terms of deformation; in addition, the ADC in terms of stress is greater than that in terms of deformation. When the soil’s compressive indices are lower than the permeability indices, ignoring the soil’s nonlinearity will under-estimate the consolidation rate of the composite ground; however, when the soil’s compressive indices is greater than the permeability indices, the reverse is true, i.e. ignoring the nonlinearity will over-estimate the consolidation rate. For the ADC based on stress, when the soil’s compressive indices are lower than the permeability indices, the increase in the stress increment within the ground due to the external loads leads to an acceleration of the consolidation rate; however, when the compressive indices is larger than the permeability indices, the increase in the stress increment causes a reduction in the consolidation rate. For the ADC in terms of deformation, whether the compressive indices are lower or larger than the permeability indices, an increase in the stress increment within the ground always accelerates the consolidation rate of the composite ground.

Key words: consolidation, composite ground, stone column, nonlinearity, logarithm model, compressive indices, permeability indices