Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments.However,whether a slope can actually seal pore air continues to be debated by researchers.In this study,a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope,and a field experiment is conducted to realistically test the sealing conditions of a slope.According to the numerical simulation,the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the“inhalation zone”and“overflow zone”,respectively.Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level,and it causes pore air pressure to reach the cm level.A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration.Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process.The monitoring results show that the pore air pressure in the slope changed,which indicates that the slope can seal air.Moreover,the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall,which agrees well with the numerical simulation results.
