基于室内单井注抽试验的潜水含水层弥散度反演机理探究  

Research on inversion mechanism of unconfined aquifer dispersivity based on indoor single-well push-pull test

作　　者：彭宇辉 文章 朱棋 姜磊玉 PENG Yuhui;WEN Zhang;ZHU Qi;JIANG Leiyu(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China)

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430078

出　　处：《安全与环境工程》2025年第2期255-263,共9页Safety and Environmental Engineering

基　　金：国家自然科学基金项目(42022082);湖北省重点研发计划项目(2022BCA073)。

摘　　要：单井注抽(single-well push-pull,SWPP)试验因其成本低、周期短以及操作简单的优点,被广泛用于求取含水层弥散度等水文地质参数。本文开展了潜水含水层SWPP室内试验研究,分析了抽出速率和潜水含水层初始厚度对穿透曲线(breakthrough curve,BTC)的影响,采用COMSOL Multiphysics有限元软件建立了潜水含水层SWPP试验数值模型,引入动网格模块进行求解,并利用数值模拟结果拟合室内试验示踪剂穿透曲线以验证模型的可靠性。此外,基于近似潜水井流动力学理论提出了新的解析解,求取了潜水含水层弥散度并进行了误差分析。结果表明:①随着抽出速率的增大,BTC下降速率更快,井筒内溶质浓度达到井筒内初始值的时间提前;②随着含水层初始厚度的增大,BTC下降速率变慢;③潜水含水层SWPP试验数值模型的解与室内SWPP试验结果拟合的纳什效率系数均大于0.98,验证了数值模型的可靠性;④随着井筒内水位降深与含水层初始厚度比值的增加,计算得到的相对误差系数增大,说明本研究提出的SWPP试验解析解求解潜水含水层弥散度的误差增大。The single-well push-pull(SWPP)test has been widely used to obtain hydrogeological parameters such as dispersivity due to its advantages of low cost,short cycle and simple operation.In this study,we conducted a laboratory-based experimental study on SWPP test for unconfined aquifer.We analyzed the impact of extraction rates and aquifer initial thicknesses on the breakthrough curve.We also developed a numerical model for the unconfined aquifer SWPP test using the finite element software COMSOL Multiphysics and incorporated the dynamic grid module for solution.We utilized he numerical simulation to fit the laboratory tracer breakthrough curve(BTC),validating the reliability of the model.In addition,we proposed a new analytical solution based on the theory of approximate phreatic water well flow mechanics.The study determined the aquifer dispersion and conducted an error analysis.The findings are as follows:①As the extraction rate increases,the decline rate of the breakthrough curve accelerates,resulting in an earlier arrival of the solute concentration in the well at its initial value.②With the increase of aquifer initial thicknesses,the decline rate of BTC curve slows down.③The Nash-Sutcliffe efficiency coefficients fitted by the numerical model of the SWPP test for the unconfined aquifer and the indoor SWPP test results are both greater than 0.98,verifying the reliability of the numerical model.④With the increase of the ratio between the drawdown in the well and the aquifer initial thicknesses,the calculated relative error coefficient increases,indicating that the error of the SWPP analytical solution proposed in this study to solve the dispersion of the unconfined aquifer increases.

关 键 词：单井注抽(SWPP)试验 潜水含水层 弥散度 误差分析 

分 类 号：X14[环境科学与工程—环境科学]