Modeling the effect of suction change on a tropical black clay aquitard during consolidation

Consolidation of clayey contaminant barriers such as aquitards (natural aquifer barriers) and landfill liners can be a cause for early breakthrough of contaminants. The general objective of this research was to numerically model the rate of dissipation of pore pressures (soil suction) and change in the void ratio/soil permeability characteristics for a loaded black cotton soil (BCS) aquitard layer and thus evaluate the level of groundwater protection in semi-arid regions with BCS cover. Soil suction change was simulated by varying the degree of saturation of the expansive black clay and applying consolidation pressure. A modified Terzaghi's 1-D consolidation equation was modeled using experimental data from the compressibility characteristics of Black cotton soils for various degrees of saturation. Proposed models for predicting the rate of dissipation of pore pressures and change in void ratio were established for the loaded BCS aquitard layer. The modeling results demonstrate the significance of evaluating the hydraulic properties of soils in relationship to their environments under simulated groundwater table and degree of saturation conditions.