Three-dimensional forward modeling and response characteristics analysis of foundation pit leakage electric-field considering electrokinetic effect  

考虑动电效应的基坑渗漏电场三维正演及响应特征分析

作　　者：Chen Yu-Feng Chen Hui Deng Ju-Zhi Liu Sui-Ming Tang Wen-Wu Wang Shuo 陈煜烽;陈辉;邓居智;刘遂明;汤文武;王烁(东华理工大学地球物理与测控技术学院,江西南昌330013;核资源与环境国家重点实验室,江西南昌330013)

机构地区：[1]School of Geophysics and Measurement-Control Technology,East China University of Technology,Nanchang 330013,China [2]State Key Laboratory of Nuclear Resources and Environment,Nanchang 330013,China

出　　处：《Applied Geophysics》2022年第1期117-131,146,共16页应用地球物理（英文版）

基　　金：partially supported by the National Natural Science Foundation of China (Nos. 41864004 and 41674077);Jiangxi Provincial Academic Leaders (Youth) Training Program (No. 20204BCJL23058);Open Fund from Engineering Research Center for Seismic Disaster Prevention and Engineering Geological Disaster Detection of Jiangxi Province (SDGD202102)。

摘　　要：The traditional ground direct current method is not suitable for leakage detection of underground diaphragm walls in foundation pits because of its low accuracy and poor anti-noise ability.Here,we propose a joint surface-borehole observation device for leakage electric fi eld detection to achieve rapid measurement of the electric fi eld distribution characteristics at ground level in the foundation pit,thus enabling rapid localization of leakage points.We first establish the mechanism and basic equation of the leakage electric field response by combining the electric field formed by electrokinetic effect(EK)and the stable electric fi eld formed by conduction current in a combined leakage channel.Then,the fi nite–infi nite element coupling method is used to solve the electric fi eld equation to simulate the responses of a three-dimensional foundation pit leakage model.Furthermore,we conduct numerical simulations of diff erent pit models to investigate the infl uencing factors of the detection device and response characteristics of the change in the properties of the leakage channel.The results demonstrate that the proposed joint surface-borehole observation device can effi ciently reveal anomalous potential caused by leakage,and the amplitude of the electric fi eld generated by EK can eff ectively strengthen the leakage electric fi eld signal at the leakage,thus improving detection accuracy and effi ciency.针对传统的地面直流电法对基坑连续墙渗漏探测精度差、抗干扰能力低以及渗漏电场响应特征分布不清等问题,本文将渗漏通道内由于动电效应形成的电场和传导电流形成的稳定电场进行耦合建立了渗漏电场的响应机制及基本方程;构建了一种井-地联合观测的渗漏电场检测装置,该装置在辅助井和降水井内供电,基坑内地面快速测量电场分布特征,从而实现渗漏点的快速定位;然后利用有限元-无限元耦合法求解电场方程实现基坑渗漏模型三维正演模拟,并对检测装置的影响因素和不同渗漏通道的基坑模型进行数值模拟。结果表明:本文提出井-地联合观测装置可快速揭示渗漏引起的电位异常,动电效应产生的电场有效加强了渗漏处渗漏电场信号,从而提高了探测精度及探测效率。

关 键 词：Foundation pit leakage 3D forward modeling Electrokinetic effect Leakage electric field 

分 类 号：P631.3[天文地球—地质矿产勘探]