【摘要】 考虑到填埋场渗滤液中较高Na⁺和Ca²⁺浓度会让土-膨润土的渗透系数显著增大，从而加速高危害性污染物击穿土-膨润土阻隔墙，建立了Na⁺和Ca²⁺作用下土-膨润土阻隔墙-含水层系统中有机物污染物运移数值模型。该模型可以考虑渗透系数和水动力弥散系数等参数随Na⁺和Ca²⁺浓度的变化。利用有限差分法，获得了该模型的数值解。通过将所建模型的计算结果分别与已有解析解计算结果和COMSOL软件计算结果进行对比分析，验证了模型的正确性。最后基于所建数值模型，以甲苯作为代表性有机污染物分析和讨论了考虑和未考虑土-膨润土化学相容性、水头差和膨润土掺量对阻隔墙长期服役性能的影响。结果表明：考虑土-膨润土化学相容性之后，阻隔墙从不会被击穿变成了服役75 a后被击穿，服役寿命大幅缩短；降低阻隔墙两侧水头差，能够有效延缓污染物的击穿时间；阻隔墙膨润土掺量的下限值应在原先防渗要求的基础上适当提高，以应对污染物作用下墙体防污阻隔性能的削弱。更多还原

【Abstract】 Considering the high concentrations of Na⁺ and Ca²⁺ in the leachate of landfills, the hydraulic conductivity of soil-bentonite will increase significantly, thereby accelerating the high-risk pollutants to break through the soil-bentonite cutoff wall. A numerical model for the transport of organic contaminants in the soil-bentonite cutoff wall-aquifer system under the action of Na⁺ and Ca²⁺ is established. This model can consider the changes in parameters such as hydraulic conductivity and hydrodynamic dispersion coefficient with the concentrations of Na⁺ and Ca²⁺. The numerical solution of the model is obtained by the finite difference method. The correctness of the model is verified by comparing its calculated results with the existing analytical solutions and those of the COMSOL software. Finally, based on the established numerical model, the effects of chemical compatibility of soil-bentonite, water head difference and bentonite content on the long-term service performance of the cutoff wall are analyzed and discussed with toluene as a representative organic pollutant. The results show that after considering the chemical compatibility of soil-bentonite, the cutoff wall changes from never breaking down to breaking down after 75 years of service, and the service life is significantly reduced. Reducing the water head difference at both sides of the cutoff wall can effectively delay the breakthrough time of contaminant. The lower limit of the bentonite content of the cutoff wall should be appropriately increased on the basis of the original anti-seepage requirements to deal with the decrease of anti-fouling barrier performance of the cutoff wall under the action of contaminants.更多还原