This paper proposes an analytical solution of two-dimensional mobile-immobile model (MIM) for contaminant transport through a composite liner including a geosynthetic clay liner (GCL) and a soil liner (SL). The effects of the soil heterogeneity and non-uniform contaminant distribution in the leachate on contaminant transport are taken into consideration. A cylindrical tank experiment and a numerical approach are conducted to verify the accuracy of the solution. The effects of the contaminant source distribution, flow conditions, composite liner properties and mass exchange on contaminant transport are illustrated. The results show that the mass exchange between the mobile and immobile regions and the contaminant distribution can significantly influence the contaminant transport in the composite liner. Additionally, the performance of the composite liner can be improved with the decrease of the volumetric water content of mobile region (θm) when θm ≤ 0.3. This is mainly because the contaminant transport will be slowed down as the hydraulic conductivity of the SL decreases with the decrease of the θm. Moreover, the variations of θm and standard deviation of contaminant distribution pose the relatively more significant effect on the contaminant transport compared with other parameters in the early time (t < 13.5 years) and later time (t > 15 years), respectively. The proposed analytical solution can provide a more accurate prediction for the performance of the composite liner and offer advice for the design of the landfill barrier system.

中文翻译：

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污染物通过异质 GCL/SL 复合材料衬垫的迁移：实验和分析研究


本文提出了一种二维移动固定模型 （MIM） 的解析解决方案，用于通过复合衬垫（包括土工合成粘土衬垫 （GCL） 和土壤衬垫 （SL））的污染物运输。考虑了土壤异质性和渗滤液中污染物分布不均匀对污染物迁移的影响。通过圆柱形水箱实验和数值方法验证了解的准确性。说明了污染物源分布、流动条件、复合材料衬里特性和质量交换对污染物传输的影响。结果表明，移动区域和固定区域之间的质量交换以及污染物分布会显著影响复合材料衬垫中的污染物传输。此外，当 θm ≤ 0.3 时，随着移动区体积含水量 （θm） 的减小，复合衬垫的性能可以提高。这主要是因为随着 θm 的减小，SL 的水力传导率会降低，因此污染物的传输会减慢。此外，与早期 （t < 13.5 年） 和后期 （t > 15 年） 的其他参数相比，污染物分布的 θm 和标准差的变化对污染物传输的影响相对较显著。所提出的分析解决方案可以更准确地预测复合材料衬垫的性能，并为垃圾填埋场屏障系统的设计提供建议。