Experiment in metal disturbance during advanced detection using a transient electromagnetic method i

Tunneling machines,or excavators,are large and good conductors and affect the reliability of data gathering and interpretation in advanced detection using transient electromagnetic methods.In our experiment,we used a coincident-loop and central loop type of configuration,where the coil plane 1) vertical to and 2) parallel to the working face.A SIROTEM instrument at different locations was used to observe the transient electromagnetic responses of the excavator and to analyze the response amplitudes.The result shows that the tunneling machine affects the advanced detection data and is related to the way the coil is coupled.When the excavator is 6 m from the observatory,the interference of tunneling machine can be ignored.