In order to make up for the defect of insufficient positioning ability of electrical detection method in dam disease de-tections,it is particularly important to study the response law of transient electromagnetic method to detect leakage hazards of earth-rock dams.By constructing a geophysical model of a dam and using the time-domain finite element method for three-dimen-sional numerical simulation,the diffusion process of transient electromagnetic field and the characteristics of induced electromotive force attenuation curve under different electrical characteristics and burial depths of the leakage zone were compared and ana-lyzed.The acquired abnormal response curve,apparent resistivity curve and apparent resistivity profile were further analyzed.The results showed that transient electromagnetic responded significantly to leakage hazards and we clarified the diffusion law of transi-ent field inside the dam body.The transient electromagnetic response time of the leakage zone was mainly concentrated in the early delay stage.The maximum response amplitude and time of different types of abnormal bodies were different,proving the feasibility of using transient electromagnetic method to detect leakage of earth-rock dams theoretically.The field test further proved that the transient electromagnetic method was accurate in determining the locations of leakage hazards.The research results can provide a reliable technical basis for reservoir hidden danger investigation and controlling.
关键词
土石坝/低阻渗漏带/瞬变电磁法/大坝地球物理模型/三维正演
Key words
earth rock dam/low resistance leakage zone/transient electromagnetic method/geophysical model of dam/3D forward modeling
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