Two-dimensional transport study for heavy metal pollutants in a cutoff wall-aquifer system considering both consolidation behavior and Langmuir adsorption features

Consolidation behavior of the cutoff walls will alters their porosity, thereby influencing their long-term service performance. In this paper, a two-dimensional transport model for heavy metal pollutants (HMPs) in the cutoff wall-aquifer system is built, incorporating both consolidation behavior and Langmuir adsorption features for the first time. The model's numerical solutions are acquired via the method of finite difference, and its validity is exhibited upon three comparisons. Thereafter, the analyses suggest that the cutoff wall's anti-fouling performance is improved when the consolidation behavior is considered relative to when it is ignored, which is attributed to porosity reduction induced by effective stress. The relative concentrations of HMPs obtained from the Langmuir adsorption model are consistently higher than those of a linear adsorption model, and such difference shows a growing tendency with concentration. Furthermore, a case study reveals that as the reduction factor of shear strength influencing the effective stress distribution increases from 0.1 to 0.7, the defined breakthrough time [Formula: see text] declines from 88.6 to 71.4 years. This study provides a more realistic basis for evaluating the blocking performance of cutoff walls against HMPs and offers a simplified method for determining their design thickness.