Physical model experimental research on ultra-shallow exploration of transient electromagnetic method

摘要

This paper studied the detection problem by using physical model experiments that about ultra-shallow exploration of transient electromagnetic method (TEM).Firstly,three antenna devices of TEM (coincident loop1,coincident loop2 and central loop) were produced,then seven physical experiment models were designed for each device.Accordingly,transient electromagnetic method multi-channel sections were obtained through the experiments.By analysing the multi-channel sections of the different physical models,it was shown that the transient electromagnetic method response characteristics are in direct proportion to abnormal body size and number,but in inverse proportion to the buried depth.Multi-turn little loop can not distinguish when the distance between two abnormal bodies is less than the side length of the device,but can distinguish when the distance between two abnormal bodies is larger than or equal to two times the side length of the device.By changing the size and the type of the antenna device,transient electromagnetic method can detect ultra-shallow (less than 0.5m) abnormal body,therefore the transient electromagnetic method can be used to detect many engineering problems,for example:reinforced quantifies in walls,bridges or roads.