Detection Capability and Application Analysis of the Small-Loop Transient Electromagnetic Method

When working in the areas with strong interference and limited sites, such as cities, dams, and mountainous areas, using the conventional transient electromagnetic (TEM) devices is difficult to lay out large transmitter loops for conventional surveys. The small-loop transient electromagnetic method, which has the advantages of lightweight and high efficiency, is a new technology of current researches. First of all, A one-dimensional (1-D) layered model and a three-dimensional (3-D) homogeneous half-space model were established by using numerical simulation method. The research results show that the small-loop TEM devices can not only accurately reflect the anomaly information of deep targets, but also be more sensitive to the detection of shallow targets. By using high-current technology, the signal intensity and detection depth of multi-turn small-loop TEM devices and that of large loop device are the same. Finally, the accuracy and effectiveness of small-loop devices were verified through analysing the results of dam karst investigation. The research work provides a reference for the qualitative analysis of response characteristics and data interpretation of small-loop TEM.