Simulation Study on Electromagnetic Response Characteristics of Unfavorable Geological Body Under Complex Conditions

The second phase of the Chongqing Rail Transit Line project has poor rock and soil stability, slow construction progress, complex and variable geological conditions, and development of groundwater, which seriously threatens the safety of life and property. Therefore, this paper takes this as the engineering background to carry out a simulation research of the electromagnetic response characteristics of the unfavorable geological body under complex geological conditions. The results show that the maximum eddy current is formed in the poor geological body, indicating that the transient electromagnetic method is more sensitive to the low resistance body. The closer the tunnel face, the greater the thickness, and the larger the scale, the stronger the electromagnetic response. The induced electromotive force curve of the B value and the Z axis component of the electromagnetic induction intensity shows that the mutual influence of the two bad geological bodies is small. When there is a low-resistance karst body behind the tunnel face, it will have less impact on the detection of bad geological bodies directly in front of the tunnel face. When the metal body is close to the tunnel face, the detection curve of the induced electromotive force in front of the tunnel face is different from when there is no metal body. When the metal body is more than 30 m away from the tunnel face, the impact on the detection result is limited.