岩溶山区坡面一孔多层地下水监测试验及科学意义  

Experiment of monitoring multi-layer groundwater at a karst hill slope and its scientific significance

作　　者：郭芳[1,3] 姜光辉 刘凡 李志杰[1] GUO Fang;JIANG Guanghui;LIU Fan;LI Zhijie(Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MNR&GZAR/International Research Centre on Karst under the Auspices of UNESCO,Guilin,Guangxi 541004,China;College of Civil Engineering and Architecture,Guangxi University,Nanning,Guangxi 530004 China;Pingguo Guangxi,Karst Ecosystem,National Observation and Research Station,Pingguo,Guangxi 531406 China;Guangxi Provincial Engineering Research Center of Water Security and Intelligent Control for Karst Region,Guangxi University,Nanning,Guangxi 530004 China)

机构地区：[1]中国地质科学院岩溶地质研究所/自然资源部、广西岩溶动力学重点实验室/联合国教科文组织国际岩溶研究中心,广西桂林541004 [2]广西大学土木建筑工程学院,广西南宁530004 [3]广西平果喀斯特生态系统国家野外科学观测研究站,广西平果531406 [4]广西大学广西岩溶区水安全与智慧调控工程研究中心,广西南宁530004

出　　处：《中国岩溶》2024年第3期491-499,共9页Carsologica Sinica

基　　金：国家自然科学基金资助项目(42172287,42272303);广西自然科学基金(2020GXNSFDA238013);桂林岩溶地质广西野外科学观测研究站(科研能力建设)(桂科23-026-274);国家自然科学基金(41472239)。

摘　　要：钻孔是揭露含水层结构和开展地下水监测的重要载体。在场地地下水监测中,不分层的丛式钻孔存在成本高、代表性不全等缺陷。“一孔多层”分层监测对水头或溶质分布的区分度高,在孔隙和裂隙含水层应用广泛,但岩溶介质因结构复杂,极少有案例研究。文章对丫吉试验场西坡径流小区的一个钻孔(ZK6)进行分层并开展监测。依据钻孔岩芯编录资料、抽水试验以及水化学与温度测孔的结果,判断岩溶发育的特征,确定将ZK6孔划分为四层,实施了钻孔封隔。对四个层位的水文观测发现,四个层位的水位动态对降雨的响应有较大差异。其中,第一层一个水文年中无水和充水状态时长分别占79%和21%,说明该层的岩溶介质处于充水和无水交替,且更多时间处于无水状态;第二层水位响应滞后明显;第三层和第四层水头差异表现出地下水排泄区的水头垂直分布特征。ZK6孔四个层位的水化学存在差异,表明岩溶介质结构的差异不仅影响了水文过程也影响水化学特征。第四层的电导率基本稳定在450μS·cm^(-1),而第二层因表层元素积累和水更新速率慢,电导率是第四层的2倍,第一层电导率的剧烈变化则反映表层岩溶带受到降雨补给影响最为强烈。综合钻孔分层的水文和水化学特征,认为第一至第四层分别代表表层岩溶带、裂隙基质带、上部饱水带和下部饱水带。岩溶山坡的“一孔多层”分层技术难度大,但一旦实现不仅可以认识岩溶垂向分带的水动力机制,也为地下水分层开发利用技术突破提供了可能。The heterogeneity of karst aquifers and the complexity of karst hydrogeological conditions pose significant challenges to groundwater observation compared to the groundwater in pore and fissure aquifers.In the areas of springs or underground rivers in which lack natural groundwater outcrops,borehole drilling is crucial for us to reveal aquifer structures and monitor groundwater.Clustered single-hole drilling inadequacies are pronounced in karst regions,because we need numerous times of single-hole drillings to comprehensively reveal different aquifer conditions,which may in turn result in land occupation and high costs.Besides,the difficulty in accurately locating karst conduits or fractures,due to complex hydrogeological conditions,may contribute to potential incompleteness of single-hole representativeness.Finally,drilling for groundwater monitoring may traverse multiple geological layers,causing interconnection of groundwater,thereby making it impossible for us to distinguish water quality conditions in different layers or channels during groundwater quality monitoring.The drilling of one shaft with multi-layer borehole refers to the technique that can achieve segmentation of multiple layers within a single borehole drilling operation.This technique,also known as Continuous Multichannel Tubing(CMT),is an internationally recognized method for layered drilling monitoring,is widely utilized in North America but seldom used in China.Because the technique of one shaft with multi-layer monitoring demonstrates its high ability in differentiating water head or solute distribution,it has been extensively applied in monitoring in pore and fissure aquifers,but seldom in karst media because of its complex structure.Therefore,there are no reported cases of application of this technique in karst regions,and its feasibility needs to be confirmed.The Yaji karst hydrogeological experimental site(hereinafter referred to the Yaji experimental site)represents a typical bared karst aquifer system in Southern China.The aquifer comp

关 键 词：坡面水文 钻孔多层监测技术 表层岩溶带 岩溶水 丫吉试验场 

分 类 号：P641[天文地球—地质矿产勘探]