中间粗夹层对沿海含水层中地下坝上游残留盐水清除的影响  

Influence of Coarse Interlayer on the Removal of Residual Saltwater upstream of Subsurface Dams in Coastal Aquifers

作　　者：岳志良 谭利华 闫磊 刘港 YUE Zhi-liang;TAN Li-hua;YAN Lei;LIU Gang(Road&Bridge Group No.1 Highway Engineering Bureau No.3 Engineering Company,Beijing 101102,China;Chongqing Three Gorges University,Chongqing 404100,China;China Construction Sixth Engineering Bureau Co.,Ltd.,Tianjin 300171,China)

机构地区：[1]中交一公局第三工程有限公司,北京101102 [2]重庆三峡学院,重庆404100 [3]中国建筑第六工程局有限公司,天津300171

出　　处：《中国农村水利水电》2024年第5期122-130,146,共10页China Rural Water and Hydropower

基　　金：中国博士后科学基金面上项目(2023MD734111);重庆市自然科学基金面上项目(CSTB2023NSCQ-MSX0853);重庆市教委项目(KIZDK202301205)。

摘　　要：海水入侵对于沿海地下淡水资源的不利影响,极大地制约了沿海地区的社会经济发展。在沿海非承压含水层中修建地下坝,是防止海水入侵并保障沿海地下水资源安全的常用措施。在实际工程中,沿海含水层往往都是异质性的,特别是分层非均质性分布广泛。为深入探究沿海含水层的分层非均质性(含水层中间存在一个高渗透性夹层)对地下坝上游残余盐水清除过程的影响,基于SEAWAT-2000程序构建野外尺度下的二维海水入侵数值模型。利用该模型分析了针对不同地下坝高度、地下坝位置及高渗透性夹层厚度等多种情景下的残余盐水运移的变化规律。模拟结果表明,地下坝的合理布置可显著降低海水入侵范围与程度,相对于均质含水层,中间高渗透性夹层的存在将增大海水入侵的距离并降低盐水楔的高度。地下坝高度大于大坝所在处的盐水楔高度时,才能有效防止海水入侵并清除坝后残余盐水。残余盐水的清除时间将随着地下坝高度的增大而增加;同时,地下坝的布置位置与海洋边界的距离越近,清除坝后残余盐水所需的时间就越长。高渗透夹层的存在极大地改变了残余盐水的脱盐时间,与均质含水层相比,含有中间粗夹层的含水层的残余盐水清除时间将延长。研究还发现,随着中间粗夹层厚度的增大,残余盐水的清除时间将先增大后减小,但其影响相对于地下坝高度与位置而言较小。The adverse impacts of seawater intrusion on coastal subsurface freshwater resources have significantly constrained the socio-economic development of coastal areas.The construction of subsurface dams in coastal unconfined aquifers is a common measure to prevent seawater intrusion and to safeguard coastal groundwater resources.In practical engineering,coastal aquifers are often heterogeneous,especially with a wide distribution of layered heterogeneous.In order to investigate the influence of the layered heterogeneous of the coastal aquifer(a highly permeable interlayer exists in the middle of the aquifer)on the removal process of residual saltwater upstream of subsurface dams,a two-dimensional numerical model of seawater intrusion at the field scale was constructed based on the SEAWAT-2000 program.The model was used to analyze the pattern of change in residual saltwater transport for a variety of scenarios,including different subsurface dam heights,subsurface dam locations,and high permeability interlayer thicknesses.The simulation results show that the reasonable arrangement of subsurface dams can significantly reduce the range and extent of seawater intrusion,and the existence of intermediate high permeability interlayers will increase the distance of seawater intrusion and reduce the height of the saltwater wedge relative to homogeneous aquifer.The height of the subsurface dam is greater than the height of the saltwater wedge at the location of the dam in order to effectively prevent saltwater intrusion and remove residual saltwater behind the dam.The time for removal of residual saltwater will increase with the height of subsurface dam;meanwhile,the closer the placement of the subsurface dam to the maritime boundary,the longer it will take to remove the residual saltwater behind the dam.The presence of a highly permeable intercalation greatly alters the desalination time of the residual saltwater,and the residual saltwater removal time will be extended in an aquifer containing an intermediate coarse intercalat

关 键 词：海水入侵 地下坝 残余盐水 高渗透夹层 数值模拟 

分 类 号：TV138[水利工程—水力学及河流动力学]