Hydro-mechanical response with respect to the air ventilation for water filtration in homogeneous soil

When water penetrates into soil, interstitial air can become trapped by the infiltrating water. Neglecting the effect of air ventilation could cause deviations in the predicted pore water pressure and the associated effective stress. This study aims at the effect of air ventilation on the coupled hydromechanical responses in homogeneous soil during infiltration. A schematic concept of infiltration conditions (open- and closed-valve) in homogeneous soil is proposed for investigating their impacts on the pore water pressure and effective stress. Experiments of vertical soil column filled with Ottawa sand (ASTM C778 20/30) were designed for two types of air ventilation (namely, open and closed infiltration). The evolution of pore water pressure at the cylinder bottom was recorded, and served as a benchmark problem for evaluating the coupled hydro-mechanical response. Coding with the commercial software, GeoStudio, was employed for the dynamic behaviors of pore-water and -air pressures as well as the evolving effective stress. It was found in both the experiments and numerical investigations that the infiltration condition plays a crucial role for the ascending rate of pore water pressure as well as the associated effective stress. These results illustrate the inevitable impacts of the air ventilation conditions on the mechanical properties of the soil during infiltration.