Estimation of hydraulic conductivity of saturated sand-marine clay mixtures with a homogenization approach

A series of oedometer tests was performed on pure marine clay and sand-marine clay mixtures with various initial water contents in the clay matrix and sand fractions. The hydraulic conductivity was computed from the compressibility and the consolidation curves of the samples. The experimental data indicated that the overall hydraulic conductivity of the mixtures depends on both the initial water content and the sand fraction of the clay matrix at a given stress level. The initial water content of the clay matrix had an influence on the local void ratio, leading to differences in the overall hydraulic conductivity. The influence of the initial water content was substantially reduced for the relationship between the overall hydraulic conductivity and the overall void ratio. A homogenization approach was introduced to estimate the overall hydraulic conductivity that could be determined from the intrinsic permeability parameters of pure marine clay. The proposed model has four parameters, including two intrinsic parameters of the pure marine clay and two additional ones incorporating the evolution of the sand skeleton. The ability of the proposed model to describe the permeability behavior of the sand-marine clay mixtures (and other sand-clay mixtures described in the literature) was verified by use of test data.