基于参数敏感性分析的轻质非水相液体在非均质包气带中迁移模拟研究  

A simulation study of the migration of light non-aqueous phase liquid in heterogeneous vadose zone based on parameter sensitivity analysis

作　　者：徐云翔 左锐[1,2] 潘明浩 武子一 王金生[1,2] 黄晨曦 XU Yunxiang;ZUO Rui;PAN Minghao;WU Ziyi;WANG Jinsheng;HUANG Chenxi(College of Water Sciences,Beijing Normal University,Beijing 100875;Engineering Research Center of Groundwater Pollution Control and Remediation,Ministry of Education,Beijing 100875)

机构地区：[1]北京师范大学水科学研究院,北京100875 [2]地下水污染控制与修复教育部工程研究中心,北京100875

出　　处：《环境污染与防治》2023年第4期450-457,463,共9页Environmental Pollution & Control

基　　金：国家重点研发计划项目(No.2020YFC1806600);国家自然科学基金资助项目(No.41877181、No.41831283)。

摘　　要：利用TOUGH2程序构建室内实验尺度多相流数值模型,基于扰动分析法,对模型中的介质孔隙度、绝对渗透率、残余水饱和度(S wr)、残余非水相(NAPL)饱和度(S nr)、进气值参数(α)进行敏感性分析,在此基础上设计中砂夹粗砂层和夹细砂层两种非均质条件情景,探究轻质非水相液体(LNAPL)以不同速率泄漏以及地下水位波动时的迁移过程。结果表明:(1)模型参数敏感度呈绝对渗透率>S nr>α>S wr>孔隙度的规律,S nr、α、S wr与LNAPL稳定饱和度呈正线性相关,绝对渗透率与其呈负线性相关。(2)主要由于介质间绝对渗透率的差异,中砂介质中的细砂夹层阻滞、粗砂夹层促进LNAPL迁移,泄漏速率的增大致使细砂夹层阻滞作用更为显著。(3)地下水位波动扩大LNAPL横、纵向污染范围,降低夹层内LNAPL饱和度,水位上升,细砂夹层下界面、粗砂夹层上界面阻滞LNAPL抬升,主要由于介质绝对渗透率的差异,两种非均质情景对地下水位波动的响应特征不同。A numerical model of multiphase flow on the laboratory scale was established based on TOUGH2.Sensitivity analysis of five parameters in the model,containing porosity,absolute permeability,residual water saturation(S wr),residual non-aqueous phase liquid(NAPL)phase saturation(S nr),and air-entry value parameter(α),was carried out based on the perturbation analysis method.On this basis,two scenarios of heterogeneous conditions,including the layer of medium sand with coarse sand and the layer of medium sand with fine sand,were designed to explore the migration process of light non-aqueous phase liquid(LNAPL)when leaking at different rates and during groundwater fluctuations.The results showed that:(1)the sensitivity of model parameters was ranked as absolute permeability>S nr>α>S wr>porosity.LNAPL stable saturation had a positive linear correlation with S nr,α,and S wr,and a negative linear correlation with absolute permeability.(2)Mainly due to the difference in absolute permeability between medium,the fine sand interlayer retarded the migration of LNAPL while the coarse sand interlayer promoted it.The increase of the leakage rate enhanced the retarding effect of fine sand.(3)The fluctuations of groundwater expanded the horizontal and vertical pollution range of LNAPL and reduced the saturation of LNAPL in the interface.As the water table rised,the uplift of LNAPL was retarded by the lower interface of the fine sand interlayer and the upper interface of the coarse sand interlayer.The response characteristics of the two scenarios of heterogeneous conditions were different mainly due to the difference of the absolute permeability between media.

关 键 词：LNAPL 非均质介质 包气带 扰动分析法 

分 类 号：X50[环境科学与工程—环境工程]