Influence of metal infrastructure on transient electromagnetic detection and effective measurement methods in complex tunnel environments

• Published in: Journal of applied geophysics Vol. 241; p. 105787
• Main Authors: Ran, Shang, Shen, Jinsong, Long, Gang, Hu, Zuzhi, Zhang, Cheng, Zhang, Jiashuo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2025
• Subjects: Metal infrastructure; Numerical simulation; TEM configurations; Transient electromagnetic method; Tunnel; Numerical simulation; Tunnel; Metal infrastructure; Transient electromagnetic method; TEM configurations
• ISSN: 0926-9851
• DOI: 10.1016/j.jappgeo.2025.105787

The transient electromagnetic method (TEM) is sensitive to low-resistivity anomalies, making it potentially useful for water hazard monitoring, such as detecting water-rich zones during tunneling or mining. However, metal infrastructure (e.g., steel arch supports and rails) can significantly affect TEM data, often masking the underlying geological response. The resistance of different TEM configurations to metal interference remains poorly analyzed. We used 3D modeling to investigate the impact of metal infrastructure on TEM measurements. First, we examined how offsets and detection angles influence measurements in the loop source system. Increasing the offset and aligning the detection direction with the anomaly can enhance the anomalous response characteristics. However, the effect of this configuration is further suppressed in a tunnel with more metal interference. Next, we applied the wire source system to a tunnel. Compared to the loop source system, the wire source system performs better in metal-containing tunnels. With a certain burial depth, larger electrode spacing and smaller offsets produced stronger anomalous responses. Finally, we implemented a cross-tunnel TEM configuration for anomaly detection. Our simulations demonstrate that this configuration can effectively reduce the masking effect of metal infrastructure. In summary, metal infrastructure interference is unavoidable, but an appropriate TEM configuration can enhance the characteristics of the anomalous response. •Response characteristics analysis of metal infrastructures.The impact of metal infrastructures on loop and wire sources system measurements was analyzed.•Optimal configurations for TEM survey systems.Numerical experiments were conducted to analyze effective TEM configurations for detecting low-resistivity anomalies.•Anti-interference capability testing of the perspective detection method.Detection capability is analyzed with source and receiver in separate tunnels.