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 field detection to achieve rapid measurement of the electric field 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 field formed by conduction current in a combined leakage channel.Then,the finite-infinite element coupling method is used to solve the electric field equation to simulate the responses of a three-dimensional foundation pit leakage model.Furthermore,we conduct numerical simulations of different pit models to investigate the influencing 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 efficiently reveal anomalous potential caused by leakage,and the amplitude of the electric field generated by EK can effectively strengthen the leakage electric field signal at the leakage,thus improving detection accuracy and efficiency.

School of Geophysics and Measurement-Control Technology,East China University of Technology,Nanchang 330013,China;State Key Laboratory of Nuclear Resources and Environment,Nanchang 330013,China

[1]Chen Yu-Feng;Chen Hui;Deng Ju-Zhi;Liu Sui-Ming;Tang Wen-Wu;Wang Shuo-.Three-dimensional forward modeling and response characteristics analysis of foundation pit leakage electric-field considering electrokinetic effect)[J].应用地球物理（英文版）,2022(01):117-131

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