Pore network modeling of capillary barrier effects: impact of pore sizes

Although the working principles of capillary barrier effects (CBEs) have been well explained based on unsaturated soil mechanics, the selection of materials for engineering structures with CBEs mostly relies on designers' experience or previously reported data, largely due to the lack of understanding of the microscale behavior of CBEs. This study explores the impact of pore sizes on CBEs based on pore network modeling. The results indicate that the pore size variability in either the fine or coarse layer has a remarkable influence on CBEs, with the latter having a dominating influence. A larger coarse-to-fine mean pore size ratio results in more effective CBEs. In addition to selecting materials with more uniform pore sizes, the coarse-to-fine mean pore size ratio is recommended to be >6 (median particle size ratio of 30) to ensure the performance of CBEs.