Research on the Influence of Soil Density on the Permeability Coefficient of Unsaturated Soils

The permeability coefficient of unsaturated soils is a particularly important parameter in unsaturated soil mechanics, and its value is mainly determined by the mineral composition of soil particles, pore size distribution, and water content. Existing models for predicting the coefficient generally hypothesize that the soil structure is incompressible, and only the influence of water content on the coefficient has been taken into account. However, it is found that the density of a soil mass is easy to change with the variation of external loads or buried depth in practice, and ignoring the influence created by the density variation will lead to a decrease of construction safety. To take soil density into consideration when predicting the coefficient permeability of unsaturated soils, this paper presents a calculation method by modifying the model proposed by Van-Genuchten (1980) through the relationship between the soil water characteristic curve and soil density. The comparison between the calculation and experimental results illustrates its good applicability in predicting the permeability function of deformable unsaturated soils.