Mathematical Modeling and Experimental Validation for the Performance of Soil–Bentonite Cutoff Walls Considering Chemical Compatibility

Abstract

The soil–bentonite cutoff wall (SB wall) is commonly employed as a barrier at contaminated sites. However, recent research has revealed that the performance of the SB wall material can significantly deteriorate due to the influence of contaminants, affecting its service life. This study established a theoretical framework to describe the relationships between the transport parameters of SB walls and contaminant concentration. This framework was applied in a numerical model for pollutant transport in a transition layer–SB wall–aquifer system to study the performance of SB walls considering chemical compatibility. The accuracy of this numerical model was validated through comparisons with results from experiments. Moreover, the key pollutants affecting the chemical compatibility of SB materials were identified through the analysis and discussion of the leachate composition in multiple landfills. The calculated results suggest that the chemical compatibility of SB materials is likely critical to the performance of SB walls. The breakthrough time of SB walls can be overestimated by 111.67% with constant transport parameters. Finally, the performance of SB walls under various conditions was calculated and analyzed, offering theoretical guidance for the design and construction of SB walls considering chemical compatibility.