Permeability coefficient of unsaturated soils

The fractal theory is applied to study the properties of unsaturated soils. The fractal model for the distribution of pore size in soil is established in which the distribution of pore size is expressed by fractal dimension and maximum pore size. The fractal dimension of pore size distribution is determined according to the slope of the correlative line between pore volume and pore diameter in logarithmic graphics. By using this model the soil-water characteristics and permeability coefficient of unsaturated soil are deduced and expressed in fractal dimension and air-entry value. The validity of the model is verified by experimental data.