Effects of Consolidation Stress and Chemical Compatibility on Contaminant Transport Through Soil‐Bentonite Cutoff Walls

Abstract

The soil‐bentonite (SB) cutoff wall is commonly utilized at contaminated sites to delay the contaminant transport. Current research typically assumes that their transport parameters are constant, ignoring the non‐uniform distribution of these parameters with depth caused by consolidation stress, and performance degradation due to contaminants (i.e., chemical compatibility). A two‐dimensional contaminant transport model was developed in an SB wall system, for the first time, simultaneously considering consolidation stress and chemical compatibility. A computational framework was established to obtain the numerical solution, which was then compared with analytical solutions and centrifuge tests to verify its effectiveness. Subsequently, existing models were compared, and the impact of relevant parameters on SB wall performance was analyzed. The results indicate that neglecting consolidation stress and chemical compatibility can overestimate SB wall performance, with a maximum overestimation of 139.76% for breakthrough time and a maximum underestimation of 96.25% for total flux. The spatial distribution of contaminant source and concentrations of Na+ and Ca2+ significantly impact the breakthrough time. Additionally, the bentonite content should be increased on the original standard to compensate for performance declines caused by contaminants. The thickness and position design should consider contaminant source in the shallow part, and choose a more economical combination. The proposed model can provide more comprehensive and accurate guidance for SB wall construction.