Estimating the 3D position and inclination of a planar interface with a directional borehole radar
S. Ebihara, H. Kawai and K. Wada
Journal name: Near Surface Geophysics
Issue: Vol 11, No 2, April 2013 pp. 185 - 195
Special topic: Ground-Penetrating Radar
Info: Article, PDF ( 13.96Mb )
Price: € 30
In this paper, we present a signal processing method suitable for estimating the position of a planar interface and its inclination using a directional borehole radar. The receiving directive antenna in a radar system is a coaxial-fed circular dipole array antenna in a borehole (CFCAB), which we have proposed previously. The method combines least-square fitting with a model of plane-wave incidence and uses an inverse boundary scattering transform. This approach makes it possible to estimate parameters from measurements collected at only two narrowly separated depths of a radar sonde. We give a numerical example to verify the proposed method. In this simulation, the array data were generated with the Method of Moments modified for a borehole radar. We conducted field experiments in the Nakatatsu mine in Japan, where there is a fault in the skarn. We constructed a 3D image of the fault with a directional borehole radar and the signal processing method. The image agrees well with the information obtained from boring core samples and observations in the gallery.