Based on qualitative understanding of the so-called pot-cover effect on moisture transport in the road subgrade soil

a mathematical model is proposed to analyze multi-phase transportation

heat conduction

and water-vapor transition.A one-dimensional finite element model for subgrade soil column is developed to investigate moisture transport and phase change under temperature gradient

as well as the mechanism and influencing factors of pot-cover effect.The numerical results indicate that the temperature profile and soil texture may have significant influence on pot-cover effect.Pot-cover effect is more likely observed in silt subgrade than in sand or clay subgrade.The temperature profile of lower temperature at the top subgrade more easily leads to the pot-cover effect.These results provide reference for further understanding the pot-cover effect in subgrade soil.