Physical and Numerical Evaluation of Capillary Barrier Formation and Failure

Abstract

This paper presents a study of the phenomenon of capillary barrier based on physical and numerical modeling. A one-dimensional physical model was developed comprised of two layers of sandy soils subjected to infiltration. The numerical simulation used the finite volume method to solve Richards’ equation. The results show the capillary barrier effect and failure, along with its relationship with the soil properties and state variables. The proposed numerical model was able to adequately reproduce the phenomena observed in the physical model. It has been demonstrated how the capillary barrier depends on the difference of unsaturated hydraulic conductivity and piezometric head between the soil layers next to their interface. Variations in interfacial conditions were presented during the process of capillary barrier formation and failure and its recovery hability after the interruption of infiltration has been demonstrated.