Publications Details

Tunnel detection using a surface line current and borehole electromagnetic field measurements

Shope, S.M.; Wayland Jr., J.R.; Lee, D.O.

A new technique for tunnel detection and location has recently been theoretically modeled and experimentally demonstrated. The objective of this research is to develop a general method for remotely detecting the presence of unauthorized tunneling activities using one or more boreholes and a surface source. A line current or dipole-dipole array, positioned on or near the surface of the earth, is used as the TE current source. Subsurface electric and magnetic field measurements are made in a borehole that is situated near a suspected tunnel location. The presence of a tunnel causes subsurface scattering of the field components created by the source. Both the electric and magnetic field strength and phase data is perturbed by the presence of a nearby tunnel. The scattered fields are observed on both sides of the tunnel relative to the source position. This paper will describe the development electromagnetic scattering models using a buried cylinder to represent a tunnel. A homogeneous whole-space model will be used. 5 refs., 20 figs.