Study On Multi-Channel Transient Electromagnetic Detection Method For Underground Pipelines

The complex distribution of urban underground pipelines,the damage caused by the safety problems is becoming more and more serious,so it is more important and urgent to detect the urban underground pipeline problem with high precision and high efficiency.Transient electromagnetic method(TEM)is sensitive to low resistivity anomalies.Because of its advantages of fast and lightweight and small volume effect,transient electromagnetic method is increasingly applied to engineering and environmental geology.Based on the above situation and the theory of transient electromagnetic method,this paper studies the transient electromagnetic detection technology of urban underground pipelines,and proposes a six channel transient electromagnetic detection method and the contents and results of the research are as follows:(1)Based on the principle of transient electromagnetic,the detection principle of six channel transient electromagnetic detection method is introduced,and the theoretical basis of multi-channel and multi-component detection method is clarified..(2)The article has verified the characteristics of the response signal of the underground metal pipeline in different channel by the physical simulation,and on this basis,the simulation experiment of the six channel detection method is carried out.The coil transceiver structure of the six channel detection method consists of a transmitting coil located in the same plane and six symmetrical and non central receiving lines.The principle of the coil is based on the consistency of the response characteristics of the first field signal response and the heterogeneity of the underground abnormal body distribution,resulting in the appearance of the two field response signals in the same channel.According to the response mechanism,the physical simulation experiments of metal pipelines with different angles,distances and positions are designed according to the response mechanism.It is found that the method can directly distinguish the location of the azimuth,the dip angle and the offset distance of the relative coil through the response signal.It is proved that the six channel transient electromagnetic detection method is applied to the distribution of underground pipelines in complex cities.