Influence of metal roadway supports on transient electromagnetic detection in mines

To study the influence of metal supports in roadways on the detection of mines using the transient electromagnetic method, authors treated metal supports including anchor nets as a thin metal layer. According to the finite differences principle, the characteristics of the full-space transient electromagnetic response under the thin metal layer's influence were calculated using a non-uniform grid. The thin metal layer's presence slowed the electromagnetic field's diffusion rate and hindered the overall diffusion. The transient electromagnetic response curve observed under the thin metal layer's influence was higher than that without the supports. Thicker metal layers resulted in higher early response values and slower decay rates. The decay rate increased as a function of time, gradually approaching that of the curve without metal supports. The simulation of the transient electromagnetic response to the model of water-containing low-resistance structures showed that the metal roadway support reduced the sensitivity of the transient electromagnetic method and weakened its response to low-resistance anomalies.