Borehole radar measurements aid structure geological interpretations

Characterization of an unstable rock mass based on borehole logs and diverse borehole radar data

“…Such data supply information on the velocity and attenuation of radar waves in the vicinity of the borehole and on the nature of reflectors distributed about the borehole (Olsson et al, 1992;Wänstedt et al, 2000;Seol et al, 2004). The principle of the single-hole reflection method is similar to that of the surface-based georadar technique, except that reflectors may occur on all sides of the borehole recording line (Fig.…”

“…Compared to surface-based georadar data, recordings in near-vertical boreholes are well suited for detecting steeply dipping features that are located more than a wavelength from the borehole, but not subhorizontal ones (Wänstedt et al, 2000). Due to the rotational symmetry of non-directional antennas operating in straight boreholes, the georadar data on their own do not provide sufficient information to determine unambiguously the locations of reflectors not intersected by the boreholes.…”

“…Olsson et al, 1992;Wänstedt et al, 2000;Washbourne et al, 2002). For optimum illumination of target structures, the lengths of the boreholes used for a crosshole survey should be substantially greater than the borehole separation.…”

Tunnel Assessment with Borehole Radar

“…Notwithstanding, non-directional antennas are usually applied in GPR borehole studies. Then, it is not always easy to correlate the different zones between the holes to the GPR images (Wänstedt et al, 2000). Other applications, as the detection of tunnels, are established even supplementary data are needed to define proper synthetic models (Di Donato et al, 2012).…”

Modeling and Migration of 2-D Georadar Data: A Stationary Phase Approach

“…Such field practice is quite distinct from 3-D seismic, in which hundreds or even thousands of recording channels simultaneously record the signals from each source point on multiple Rx lines. Three In addition to surface profiling, borehole radar experiments are also routinely carried out in support of civil and mining engineering projects [8]. Crosshole surveys, in which the radar Tx is placed in one borehole and the Rx in another, seek to scan the interwell medium in a tomographic sense to image changes in the electromagnetic (EM) wavespeed or attenuation [9].…”