摘要
复合隔离墙常用于污染场地的防污防渗工程。针对由土工膜和土-膨润土组成的复合隔离墙,考虑了污染源区有机污染物浓度沿深度不均匀分布及缓冲层的存在,建立了缓冲层-复合隔离墙-含水层系统中有机污染物二维运移理论模型。利用有限差分法对该模型进行了求解。通过对比试验测定结果、已有解析模型和COMSOL软件的计算结果,验证了所建理论模型合理性。在此基础上,研究了复合隔离墙中有机污染物的运移特性。结果显示,相比于一维运移理论模型,二维运移理论模型下复合隔离墙中有机污染物的浓度较低,这是由于有机污染物会通过竖向扩散减慢水平向运移速度。缓冲层存在有助于减缓复合隔离墙中有机污染物运移速率,且缓冲层厚度越大,所定义击穿时间t_(b)越长,墙体外侧总运移通量越小。当土工膜渗透系数从0.5×10^(-12)m/s增大到5.0×10^(-12)m/s时,对应的t_(b)将从172.8 a降低至28.2 a。鉴于隔离墙厚度及其线性吸附系数增大均可显著增强复合隔离墙的防渗效果,可结合隔离墙的吸附性能选定墙体厚度。
Composite cutoff walls are commonly used in projects aimed at preventing pollution and permeation in contaminated areas.For a composite cutoff wall made of geomembrane and soil-bentonite,a theoretical model is developed to analyze the two-dimensional transport of organic contaminants in a buffer layer-composite cutoff wall-aquifer system.This model takes into account the presence of a buffer layer and the non-uniform distribution of organic contaminant concentrations at different depths in the source zone.The model is solved using the finite difference method.Subsequently,the rationality of the proposed theoretical model is confirmed through comparison with experimental data,calculations from an existing analytical model,and simulations using COMSOL software.The study investigates the transport characteristics of an organic contaminant in a composite cutoff wall.Results show that the organic contaminant concentration in the wall is lower under the two-dimensional transport model compared to the one-dimensional model,attributed to horizontal transport slowing due to vertical diffusion.The presence of a buffer layer slows down transport in the wall,with a thicker buffer layer leading to a longer breakthrough time to and lower total transport flux at the wall exit.Increasing the geomembrane permeability coefficient from 0.5×10^(-12)m/s to 5.0×10^(-12)m/s reduces t_(b)from 172.8 years to 28.2 years.Greater cutoff wall thickness and linear adsorption coefficient enhance barrier effectiveness,allowing selection of wall thickness based on adsorption performance.
作者
江文豪
冯晨
黄啸
李江山
JIANG Wen-hao;FENG Chen;HUANG Xiao;LI Jiang-shan(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Science,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)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第S01期731-741,共11页
Rock and Soil Mechanics
基金
国家重点研发计划课题(No.2019YFC1804003)
国家自然科学基金青年科学基金项目(No.42007260)
关键词
有机污染物
复合隔离墙
二维运移
理论模型
缓冲层
击穿时间
organic contaminant
composite cutoff wall
two-dimensional transport
theoretical model
buffer layer
breakthrough time
作者简介
第一作者:江文豪,男,1996年生,博士研究生,主要从事土体固结和污染物运移耦合方面的研究。E-mail:Geo_Jiang2020@163.com;通讯作者:李江山,男,1987年生,博士,研究员,主要从事污染场地工程修复和固废资源化方面的研究。E-mail:jsli@whrsm.ac.cn
