A hydraulic conductivity model of frozen soils with the consideration of water films

Abstract

AbstractAccurate evaluation of water migration in frozen soils requires the determination of hydraulic conductivity. Most classical predictive models of hydraulic conductivity rely on the pore bundle concept that only accounts for capillary flow and neglects the water film flow. This may underestimate the hydraulic conductivity of frozen soil. In this study, water in the capillary tube was divided into free water and water films with different dynamic viscosities. Then, a novel prediction model for hydraulic conductivity of frozen soil was proposed based on the capillary flow theory. The model parameters can be easily obtained from laboratory tests. The predicted results showed good agreement with tested hydraulic conductivity of 12 frozen soils. When the temperature decreases from 0 to −1°C, the contribution of water films to the hydraulic conductivity of frozen soil becomes large, up to 20%. To further develop the predictive power of the model, the hydraulic conductivity determined by relative change method was recommended. The use of relative hydraulic conductivity can provide a simple form to quantify the influence of unfrozen water content on the hydraulic conductivity of frozen soils.Highlights Free water and water films have different dynamic viscosities in the model. Soil freezing curve was used to predict the hydraulic conductivity of frozen soils. Water film has about 20% contribution to hydraulic conductivity of frozen clay.