地下水井水位及化学组分的同震差异响应特征分析--以青白江地震为例  

An analysis of the coseismic differential response characteristics of well water levels and chemical components:A case study triggered by the Qingbaijiang earthquake

作　　者：顾鸿宇 王东辉[1] 李胜伟 郑万模[1] 刘港 向元英 李丹 陈能德 GU Hongyu;WANG Donghui;LI Shengwei;ZHENG Wanmo;LIU Gang;XIANG Yuanying;LI Dan;CHEN Nengde(Chengdu Center,China Geological Survey,Chengdu,Sichuan 610081,China;Xi’an Center,China Geological Survey,Xi’an,Shaanxi 710054,China;Sichuan Engineering Consulting and Research Institute,Chengdu,Sichuan 610016,China;Sichuan Kaiyuan Group Co.Ltd.,Chengdu,Sichuan 610081,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]中国地质调查局西安地质调查中心,陕西西安710054 [3]四川省工程咨询研究院,四川成都610016 [4]四川省开元集团有限公司,四川成都610081

出　　处：《水文地质工程地质》2021年第6期44-53,共10页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金项目(41907174);中国地质调查局地质调查项目(DD20189210,DD20211402,DD20211381)。

摘　　要：相邻监测井的同震差异响应分析是研究地下水同震响应机理的路径之--。2020年2月3号青白江地震引发了龙泉山地下水监测井水位及水质的异常变化。利用多种水化学组分及水位的自动监测数据分析了相邻两口监测井的同震差异响应特征,讨论了水化学组分及水位差异响应机理。在相同能量密度情况下,ZK1水位变幅较ZK6大,表明ZK1对本次地震响应的敏感性高于ZK6。地震主要引起了处于还原环境(E_(h)<0)的第二含水层(主要离子为NH_(4)^(+)和NO_(3)^(-))中地下水向ZK1的排泄,而处于氧化环境(E_(h)>0)的第一含水层(高浓度C1^(-),高TDS及pH)中地下水主要向ZK6排泄。不同含水层水体向井排泄和混合是造成两口井地下水化学组分差异响应的原因。根据震后井水位及水化学组分的趋势变化规律分析,岩体在地震作用下的不排水体积改变是造成地下水水位阶跃变化的主要原因,ZK1周围第二含水层发生了塑性变形,渗透性发生了永久改变,而ZK6周围岩体发生弹性变形,渗透性未发生永久改变。Analysis of the coseismic differential response of adjacent monitoring wells is an important way to study the coseismic response mechanism of groundwater.On February 3,2020,the Qingbaijiang earthquake caused the abnormal changes of groundwater levels and water quality in the monitoring wells of Longquanshan.In this paper,the coseismic differential response characteristics of two adjacent monitoring wells are analyzed by using the automatic monitoring data of various hydrochemical components and water levels.Based on the coupling response characteristics of hydrochemical components and water levels,the mechanism of differential response of hydrochemical components and water levels is discussed.In the case of the same energy density,the water level variation amplitude of well ZK1 is larger than that of well ZK6,which indicates that ZK1 is more sensitive to the earthquake response than ZK6.The earthquake mainly caused the discharge of the groundwater(E_(h)<0)from the second aquifer(NH_(4)^(+) and NO_(3)^(-))to ZK1,while the groundwater(E_(h)>0)from the first aquifer(high concentration of Cl^(-),TDS,and pH)to ZK6.The discharge and mixing of water from different aquifers into the wells are the reason for the different response of chemical components of groundwater in these two wells.According to the trends of chemical components and water levels after the earthquake,rock mass under seismic action of undrained volume change is the main cause of groundwater water status step change,that is,plastic deformation and permanent change in permeability occurred in the second aquifer around well ZK1,and no permanent change in permeability but elastic deformation occurred in rock mass around well ZK6.

关 键 词：监测井 水化学组分 水位 同震响应 含水层渗透性 

分 类 号：P641.3[天文地球—地质矿产勘探]