考虑温度变化下三层复合衬垫中重金属污染物一维运移理论模型  

Theoretical model for one-dimensional transport of heavy metal contaminants in a triple-layer composite liner considering temperature change

作　　者：江文豪 冯晨 李江山[1,3] JIANG Wen-hao;FENG Chen;LI Jiang-shan(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Hubei Province Key Laboratory of Contaminated Sludge and Soil Science and Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]中国科学院武汉岩土力学研究所污染泥土科学与工程湖北省重点实验室,湖北武汉430071

出　　处：《岩土力学》2024年第2期417-432,共16页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2019YFC1804002)。

摘　　要：针对考虑温度变化下由土工膜(geomembrane,简称GM)+土工复合膨润土衬垫(geosynthetic clay liner,简称GCL)+压实黏土衬垫(compacted clay liner,简称CCL)组成的3层复合衬垫中重金属污染物一维运移问题,基于相关假定发展得到了热传导与重金属污染物运移的控制方程,并建立了相应理论模型。通过有限差分,对所建理论模型进行了数值求解。随后,开展了与试验结果、解析解计算结果以及其他数值解计算结果的对比分析,验证了该模型的合理性。最后,以Cd^(2+)为例,分析和讨论了不同因素对运移规律的影响。结果表明,上部温度升高会使复合衬垫中Cd^(2+)的运移通量和底部浓度增大,但会使其上部浓度降低。热扩散效应对运移行为的影响会随Soret系数ST的增大而变显著,当ST为0.001、0.005、0.01、0.05、0.1 K^(-1)时,所定义的击穿时间tb依次为37.9、37.2、36.4、31.2、26.5 a。GCL和CCL最大吸附量的增大均会使t_(b)近似线性增加,且在一定渗沥液水头h_(b)下,t_(b)随GCL和CCL厚度的增大呈线性增大趋势。此外,当h_(b)从0.5m增大到1.0m时,t_(b)平均降低了8.33 a。在工程实践中,可结合GCL和CCL的吸附性能和厚度来设计复合衬垫,同时应考虑温度变化对阻隔效果的影响。Aiming at the problem of one-dimensional transport of heavy metal contaminants(HMCs) in a triple-layer composite liner composed of geomembrane(GM),geosynthetic clay liner(GCL) and compacted clay liner(CCL) under the consideration of temperature change,the governing equations for thermal conduction and HMCs transport are developed based on the relevant assumptions,and a corresponding theoretical model is established.The theoretical model constructed in this study is solved numerically by the finite difference.Subsequently,a comparative analysis with the experimental measurements,the analytical solution calculations and other numerical solution calculations is performed to validly verify the reasonableness of this model.Finally,the effects of different factors on the transport laws are analyzed and discussed using Cd^(2+) as an example.The results show that an increase in the upper temperature increases the transport flux and bottom concentration of Cd^(2+) in the composite liner,but decreases its upper concentration.The thermal diffusion effect on the transport behaviors becomes significant with an increasing in Soret coefficient ST,and the defined breakthrough times tb are 37.9,37.2,36.4,31.2 and 26.5 a for ST of 0.001,0.005,0.01,0.05 and 0.1 K^(–1) in this order.The increase in the maximum adsorption capacities of GCL and CCL leads to the approximately linear growth in tb,and under a certain leachate head hb,the tb almost increases linearly with the increase of GCL thickness and CCL thickness.Furthermore,as hb increases from 0.5 m to 1.0 m,the tb reduces by an average of 8.33 a.In engineering practice,the adsorption performance and thickness of both GCL and CCL can be combined to design a composite liner,where the influence of temperature variation on barrier effectiveness should be incorporated.

关 键 词：温度变化 热传导 重金属污染物运移 3层复合衬垫 理论模型 击穿时间 

分 类 号：X53[环境科学与工程—环境工程]