• 关键词：地下水循环井（GCWs）  二级污染源  低渗透性含水层  评估方法

• 基金项目：国家重点研发计划（No.2020YFC1808304）；国家自然科学基金（No.41602237）；长安大学中央高校基本科研业务费资助项目 （No.300102290106）；国家留学基金管理委员会资助项目（No.201906565031）

• 程大伟
• 长安大学水利与环境学院，西安 710064;长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064

• 冯申
• 长安大学水利与环境学院，西安 710064;长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064

• 杨胜科
• 长安大学水利与环境学院，西安 710064;长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064

• 张琳
• 长安大学水利与环境学院，西安 710064;长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064

• 晋浩颖
• 长安大学水利与环境学院，西安 710064;长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064

• 摘要：以地下水循环井技术（GCWs）修复含水层低渗透性透镜体内污染物为研究对象，通过解析含水层内污染物浓度的空间分布规律和时间演化过程，构建了评估循环井修复低渗透性透镜体二级污染源修复效率的评价方法.主要评价指标包括污染物平均浓度、污染物修复的时间累积效率系数和界限流线的几何特征及其上渗流入渗角度，分别用以评价瞬时修复效率、时间累积修复效率和渗流模式对污染物修复效果的影响.同时，利用COMSOL数值模拟软件，模拟了不同工况下循环井驱动的低渗透性污染源的反向扩散过程，并利用所构建的评估方法进行 评估.结果表明：①随注水口高程降低或抽水口高程升高，循环井的修复效率总体呈递减趋势，其中，注水口略高于或抽水口略低于透镜体时修复效率较高；②循环井注水/抽水的质量通量越大、透镜体的长宽比系数越大、透镜体距离循环井越近，其修复效率越高；③界限流线位于以透镜体中心为原点的二、三象限时，循环井的修复效率较好；其上渗流入渗方向垂直于透镜体的上水平界面时，修复效率较高；随界限流线与透镜体的上界面法线夹角增大，修复效率降低.

• Abstract：In this paper， the Groundwater Circulation Wells （GCWs） was used to remediate the contaminant in the low-permeability lens of the aquifer， and an evaluation method was proposed to assess the remediation efficiency of GCWs for the secondary contaminant sources in the low-permeability lens by analyzing the spatial distribution and temporal evolution of the contaminant concentration in the aquifer. The main evaluation indexes include the average concentration of contaminant， the time cumulative efficiency coefficient of contaminant remediation and the geometric characteristics of boundary streamline and its infiltration angle. They are used to evaluate the instantaneous remediation efficiency， the time cumulative remediation efficiency and the seepage mode on the remediation efficiency of contaminants， respectively. We employed the COMSOL numerical simulation software to simulate the back-diffusion process of low-permeability contaminant sources driven by GCWs under different working conditions， which was further evaluated using the developed evaluation method. Results indicated that ①the remediation efficiency of GCWs decreases with the decrease of the injection port elevation or the increase of the pumping port elevation， among which， the remediation efficiency is higher when the injection port elevation is slightly higher or the pumping port elevation is slightly lower than the lens； ②when the injection/pumping mass flux of GCWs is larger， the length-width ratio coefficient of the lens is larger and the lens is closer to GCWs， the remediation efficiency is higher； and ③the remediation efficiency is better when the boundary streamline is located in the second and third quadrants with the center of the lens as the origin. When the infiltration direction is perpendicular to the upper horizontal interface of the lens， the remediation efficiency is higher and the remediation efficiency decreases with the increase of the angle between the boundary streamline and the normal of the upper surface of the lens.

• Key words：groundwater circulation wells （GCWs）  secondary contaminant sources  low-permeability aquifer  evaluation method

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