Inspection For Earth-rockfill Dam Defects Using Transient Electromagnetic Method

With the further development and utilization of water resources, the operating environment of the dam is complicating, and the safe problems of the dam are prominent appearing. Although it has done a lot of repair and reinforcement work on the dam seepage path in our country at present time, there are still many safe problems, which the earth-rockfill dam is in the majority, the detection for the earth-rock dam hidden trouble is an important issue in hydraulic engineeringAt first, this article bases on transient electromagnetic theory, it describes the basic principles of the transient electromagnetic method detection, and several precautions and the characteristics of the transient electromagnetic detection signal, and outlines the transient electromagnetic method detection using the actual working process of the earth-rockfill dam; Secondly, it analyzes the transient process of the coil producing, and discusses the influence on the launch frequency, the magnetic strength, and the cut-off time when changes the launch coil circle numbers, and discusses the influence on the cut-off time, the signal amplitude when changes the receive coil circle numbers, in addition, it also discusses the influence on test results when changes the launch frequency and the launch window, it provides the theoretical basis for the optimization design of the coil circle number, the optimal matching of the test parameters; Finally, it based on the optimization design of the coil circle number and the optimal matching of the test parameters, it realizes the detection to the different combination of the earth-rockfill dam hidden trouble, and achieves good laboratory test results. The experimental results show that it can detect the hole and cracks hidden trouble of the earth-rockfill dam by the transient electromagnetic method. Based on the test of apparent resistivity chart analysis, can clearly see that anomalous signals point position, and through the export of useful data estimate the depth of the danger. In addition, the article discusses the existing a minimum detection depth of the transient electromagnetic method, and the test results are reliable through verify lots of experiments. The topic research provides certain theoretical foundation for the using of the transient electromagnetic method in detecting hidden application dam in the future, but it still needs further improvement.