EXPERIMENTS AND NUMERICAL MODELLING OF AIR-WATER FLOW IN UNSATURATED SOILS WITH HYSTERESIS AND AIR ENTRAPMENT

Air entrapment in soil-pores during cyclically hydraulic loading requires a physical insight by means of both modelling and experimental works. In the present study, transient drying and wetting tests are performed in a sand column device. The device enables to perform measurements of transient water content and pore water pressure in unsaturated soils. The measurements of water content as well as the pore pressure are directly linked to soil-water retention curve. The experimental results show that it exists an entrapped air together with hysteresis in soil water retention. Based on the experimental results, a new computer model of soil water retention is proposed. Finally, numerical simulation of air -water transport in unsaturated media is implemented using this model. The comparison between measured data and numerical simulation results shows that the proposed model can improve an accuracy in simulation of the water transport in unsaturated media.