Hydraulic conductivity function for unsaturated cracked soil

This paper presents a method to predict the hydraulic conductivity function for cracked soil considering crack volume changes during drying-wetting processes. The cracked soil is viewed as an overlapping continuum of a crack network system and a soil matrix system. The hydraulic conductivity functions for the two pore systems can be determined based on their pore size distributions and combined to give the hydraulic conductivity function for the cracked soil at a particular state. The hydraulic conductivity function for the cracked soil at different states along a crack development path can be obtained and combined to give the hydraulic conductivity function for the cracked soil considering crack volume changes. An example is presented to illustrate the prediction of the hydraulic conductivity functions for a cracked soil. The hydraulic conductivity is significantly affected by the presence of cracks. When the cracks are still open under saturated conditions, the hydraulic conductivity function is bi-modal. When the cracks close completely under saturated conditions and open at low suctions, the saturated permeability is dominated by the soil matrix initially. The hydraulic conductivity at low suctions may be dominated by that of the crack network, whereas the hydraulic conductivity at high suctions is controlled by the soil matrix because water cannot pass through the cracks with large apertures.