关键词: 瞬变电磁法, 低阻覆盖层, 浅埋煤层, 积水采空区, 约束反演

Abstract: In order to realize the transient electromagnetic detection (TEM) of the shallow water goaf under the low resistance overburden layer, the large transmission loop can enhance the signal, easily penetrate the low resistance overburden layer, and improve the signal-to-noise ratio of the lower data. However, the reflection signal of the shallow water goaf is mainly concentrated in the early data, and the optimal regularization parameter of the previous inversion is directly used as the back in the inversion process The model parameters of the second iteration and the constrained inversion method of controlling the step length during the iteration can overcome the disadvantage of the low resolution of the late apparent resistivity to the early signal, and realize the electrical stratification of the stratum and the spatial positioning of the goaf in the early signal. Through the establishment of the K-type geological model forward and reverse calculation, as well as the drilling verification examples, it is shown that the constrained inversion of the transient electromagnetic large magnetic moment data can realize the location detection of the shallow water goaf under the low resistance overburden layer.