An infiltration model for inclined covers with consideration of capillary barrier effect

Covers with capillary barrier effect (CCBEs) are widely used as surface cover systems in landfills, mine tailings and water-sensitive soil slopes to prevent rainwater from infiltrating into the protected materials below. In the engineering design, the water-prevention performance of the CCBEs must be quantificationally evaluated according to the local meteorological conditions. In this study, according to the moisture distribution during infiltration, the fine-grained soil layer was divided into saturated, transition and initial zones. Capillary barrier effects were analyzed by considering water migration and redistribution at the interface between fine and coarse-grained layers. Then, the total time, including the time to reach the interface (t_Hf), the time for overcoming the capillary barrier effect (t_c) and the time for passing through the coarse-grained layer (t_g), was determined to quantificationally evaluate the water-prevention capacity of the inclined CCBEs under different rainfall conditions. For the case studies selected from literature, the calculated results by the proposed model agree well with the measured data. Finally, some parameters and the factors influencing the capillary barrier effect were further analyzed.