Numerical Analysis of an Unsaturated Capillary Barrier Cover System

Inclined multi-layered barriers can be used to protect underlying waste storage facilities. The intended barriers can be used to confine the infiltration through implementation of the capillary barrier effect. In this study, the effect of rainfall, evaporation, and transpiration on the hydraulic properties of inclined covers was assessed by performing a series of simulations using HYDRUS-2D numerical models. The material of the intended layers included clay loam soil as a seepage control layer, sandy soil as a moisture retention layer, and gravel as a capillary break layer. Based on the key results of numerical analyses, Lateral diversion in the interface between the seepage control layer and moisture retention layer occurred as a result of the significant slope of said layers and the low permeability of the moisture retention layer. At the reduced degree of saturation, water did not move easily from the seepage control layer to the moisture retention layer as well as from the moisture retention layer to the capillary break layer due to the low hydraulic conductivity. The negative pressure head in the seepage control layer had minimal effect on the water content in the moisture retention layer. Hence, the performance of this protective earthen cover can, then, be guaranteed due to the current climatological conditions.