非等温分布条件下三层复合衬垫中有机污染物一维瞬态运移规律研究  

One-dimensional transient transport laws of organic contaminants in atriple-layer composite liner under a non-isothermal distribution condition

作　　者：李江山[1,2,3] 江文豪 冯晨 LI Jiang-shan;JIANG Wen-hao;FENG Chen(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》2023年第9期2717-2731,共15页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51827814)。

摘　　要：针对非等温分布条件下由土工膜(geomembrane,简称GMB)+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层复合衬垫中有机污染物一维瞬态运移问题,考虑了对流、扩散、机械弥散、吸附、降解和热扩散等因素,建立了相应的数学模型。该模型可考虑扩散系数和渗透系数等参数随温度变化。利用有限差分法,获得了该模型的数值解。通过将所建模型计算结果分别与试验结果、已有解析模型计算结果和COMSOL软件计算结果进行对比,验证了所建模型的正确性。基于所定义的击穿时间tb,以甲苯作为代表性有机污染物分析和讨论了不同因素对运移行为的影响。结果表明:(1)非等温分布条件会使渗透系数、扩散系数和线性吸附系数等参数发生变化,其中渗透系数和扩散系数的变化会加快运移过程,尤其是扩散系数,而线性吸附系数的变化会减慢运移速率;(2)复合衬垫上部和底部温度差ΔT的增大会使击穿时间tb减小,底部运移通量Jb增大;当ΔT为0、10、20、30、40 K时,对应的tb依次为65.7,58.5,54.3,52.0,51.2 a;(3)当GMB扩散系数Dm,R在3.0×10^(-14)~3.0×10^(-13)m^(2)/s之间变化时,Dm,R对tb的影响较为显著;通过对比两种情况下的tb可发现,GCL存在对运移行为的影响较小。In order to understand the one-dimensional transient transport process of organic contaminants in a triple-layer composite liner composed of geomembrane(GMB),geosynthetic clay liner(GCL)and compacted clay liner(CCL)under the non-isothermal distribution condition,the factors such as advection,diffusion,mechanical dispersion,adsorption,degradation and thermal diffusion are considered,and the corresponding mathematical model is established,in which the variations of parameters such as diffusion coefficient and permeability coefficient with temperature are incorporated.The numerical solution for the proposed model is obtained by using the finite difference method.The correctness of the established model is verified by comparing the calculation results of the model with the experimental data,the calculation results of the existing analytical model and the numerical results of COMSOL software.Based on the defined breakthrough time tb,toluene is adopted as a representative organic contaminant to analyze and discuss the influences of different factors on the transport behaviors.The results show that:(1)The non-isothermal distribution condition changes the parameters such as the permeability coefficient,the diffusion coefficient and the linear adsorption coefficient.The variations of the permeability coefficient and the diffusion coefficient accelerate the transport process,especially for the diffusion coefficient,while the variation of the linear adsorption coefficient slows down the transport rate.(2)The increase of the temperature differenceΔT between the upper and bottom of the composite liner reduces the breakthrough time tb and increases the bottom transport flux Jb. When ΔT values are 0, 10, 20, 30 and 40 K, the corresponding tb values are 65.7, 58.5, 54.3, 52.0 and 51.2 years,respectively. (3) When the diffusion coefficient Dm,R of GMB changes from 3.0×10−14 m2/s to 3.0×10−13 m2/s, the effect of Dm,R on tbis obvious. It is found that the existence of GCL has a little effect on the transport behaviors by co

关 键 词：非等温分布条件 3层复合衬垫 有机污染物 瞬态运移 击穿时间 

分 类 号：X53[环境科学与工程—环境工程]