Saturation-density dependent permeability function for unsaturated loess

The coefficient of permeability for unsaturated soil is a key parameter in performing seepage analyses on saturated/unsaturated soil.The permeability coefficient of a saturated soil is a function of bulk density,while for unsaturated soils,it is a function of the degree of saturation provided a constant bulk density.However,the bulk density of soil is usually not constant.Both the degree of saturation and the bulk density influence the coefficient of permeability of certain unsaturated soil.Based on the above viewpoints,a series of unsaturated permeability tests are carried out under different infiltration paths and dry bulk densities.The relative permeabilities are normalized under different bulk densities to determine the normalized permeability function subject to bulk density variation.Furthermore,a new test is carried out to verify the proposed normalized permeability function.The predicted curves are in good accordance with the experimental data.