摘要
构建了填埋场渗漏条件下,含水层-监测井系统水流和污染物运移的代表性概念模型.利用等效渗透系数法描述双重介质系统中的水流运动和水头分布,而多孔介质溶质运移的ADE方程和管流的一维溶质运移方程被分别用来模拟污染物在含水层和井孔中的迁移和分布,最终形成了描述渗滤液渗漏条件下监测井-含水层系统中污染物迁移分布的控制方程.基于Fortan平台,编制了该方程的有限差分求解程序,应用该程序模拟分析了填埋场渗漏条件下,地下水监测井内部及周边水流和溶质的运动、井筒存在对水流和溶质运移的影响.结果表明:井筒效应影响井孔周边的局部地下水流场和浓度场,导致井孔内下部区域污染物浓度增大,井筒外一定区域浓度减小;井筒效应的影响随着径距增加而减小,当径距大于2倍含水层厚度时,井筒效应导致的监测误差最大不超过20%.井径对井筒效应的影响较为复杂,并非单调增加.在本案例中,井径小于0.1m时,井筒效应随着井径增大而增大;反之,当井径大于0.1m后,井筒效应导致的监测误差随着井径增大而减小.含水层渗透系数和比单位弹性贮水系数越大,井筒效应的影响越小.因此具有强渗透性且孔隙度更大的卵、砾石含水层中,井筒效应的影响更小;而对于弱渗透性或中等渗透性的砂土、砂黏土含水层,井筒效应对监测效果的影响更大.
A representative conceptual model for water flow and contaminant transport in the aquifer-monitoring well system under the condition of leachate leakage was constructed. The Equivalent Hydraulic Conductivity（EHC） method was used to describe the water flow and head distribution in the dual-medium system, while the ADE equation and the 1-D solute transport equation for pipe flow were, respectively, used to simulate pollutants migration and distribution in the aquifer and in the wellbore, and eventually a governing equation describing the distribution of pollutants in the monitoring well-aquifer system under leachate emission conditions was constructed. A finite-difference method for this equation was developed based on the Fortan platform. This program was then used to simulate and analyze the effects of monitor well on the regional flow and solute movement in the interior and around the monitoring well, as well as its influence of the wellbore on the flow and solute transport. The results show that The wellbore effect affects the local groundwater flow field and the concentration field around the hole, which leads to the concentration increase in the inner and lower parts of the borehole, and the decrease of the concentration in the certain area outside the wellbore; the effect of the wellbore effect decreases with the increase of the distance. from well to leakage point. The monitoring error caused by the wellbore effect is not more than 20% when the distance is greater than 2 times the thickness of the aquifer. The influence of well diameter on wellbore effect is rather complex, not monotonic. In this case, wellbore effect increases with the increase of well diameter, reaches the maximum at 0.1 m, and then decreases. The greater the permeability coefficient of the aquifer and the greater the specific storativity, the smaller the influence of wellbore effect. Therefore, the effect of wellbore is less in the gravel and coarse gravel media aquifers with strong permeability and greater porosity, and the effect of wellbore effect on the monitoring effect is greater for the weakly osmosis or medium permeability sand and sand clay aquifers.
作者
徐亚
刘玉强
胡立堂
刘景财
董路
能昌信
XU Ya;LIU Yu-qiang;HU Li-tang;LIU Jing-cai;DONG Lu;NAI Chang-xin(Research Institute of Soil and soliid Waste,Chinese Research Academy of Environment Sciences,Beijing 100012,China;China State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China;Engineering Research Center of Groundwater Pollution Control and Remediation of Ministry of Education,Beijing Normal University,Beijing 100875,China)
出处
《中国环境科学》
EI
CAS
CSSCI
CSCD
北大核心
2018年第8期3113-3120,共8页
China Environmental Science
基金
国家自然科学基金资助项目(51708529
61503219)
北京市自然科学基金项目(8172048)
中央级院所基本科研业务专项重点项目(2016YSKY14)
山东省自然科学基金资助项目(ZR2014DL008)
关键词
数值模拟
井筒效应
填埋场
双重介质
numerical simulation
wellbore effect
landfill
dual medium
作者简介
徐亚（1985-）,男,湖南岳阳人,助理研究员,博士,主要从事固体废物处置技术、污染探测及风险评价研究.发表论文20余篇.;责任作者,副教授,xuya@craes.org.cn
