Site Investigation - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 369

Figure 13.14 Deviation of borehole direction and associated misinterpretation regarding the
dip angle of discontinuities (Wittke 1990)

13.5.4 Geophysical Logging
Because of the high cost of equipment and the required experience in interpretation
of data, geophysical borehole logging is usually provided as a service by specialized
companies.
Tables 13.2 to 13.6 give a review of methods of geophysical logging of boreholes sug-
gested by the ISRM. These are subdivided into borehole seismic, acoustic (ultrasonic)
logging, electric and electromagnetic logging, nuclear logging and miscellaneous log-
ging. For each method, the measured parameters and expected information obtained
from the results are indicated.

Table 13.2 Borehole seismic

Method References Measured

parameters

Expected
information

Seismic testing within
a borehole (downhole/
uphole seismic)

ISRM 1988,
ISRM 2006

p-wave and
s-wave
velocities and
amplitudes

dynamic elastic constants of the
rock mass and attenuation of
seismic waves along borehole,
detection of disturbed rock zones

Seismic testing
between boreholes
(crosshole seismic)

ISRM 1988,
ISRM 2006

p-wave and
s-wave
velocities and
amplitudes

dynamic elastic constants of the
rock mass between
boreholes,
detection of disturbed rock zones

Seismic tomography ISRM 2006 p-wave and

s-wave
velocities and
amplitudes

distribution profile of
velocity and/or attenuation of
seismic waves (tomogram)