A detailed description of the applications and
limitations of standard geophysical methods can be
found in the Corps of Engineers (WES) Engineering
and Design Manual “Geophysical Exploration”
(1979). Several of the above listed methods have
been introduced as a result of recently developed
geo-environmental investigation methods,
Robertson et al. (1998). The application of the cone
penetration test (CPT) for geophysical site
characterization opened new possibilities for
geophysical site characterization. The CPT has
rapidly gained acceptance and is recognized as a
valuable in-situ testing technique because of its
speed, reliability, cost-effectiveness and excellent
soil profiling capability.
Frequently used geophysical methods, which can be
used to identify geologic formations, are listed in
Table 3. Also, several recently developed methods
especially for geo-environmental investigations are
also listed. For a more detailed description of these
methods and information concerning data
interpretation of the various methods, reference is
made to Greenhouse et al. (1998), Robertson et al.
(1998), WES Engineering Manual (1979) and
Triumf (1992).
FUTURE TRENDS
In the area of geotechnical engineering, four major
trends can be identified: 1) incorporation of
geophysical sensors in geotechnical testing
equipment, such as the CPT. 2) improved
correlation between measured geophysical
parameters and geotechnical and geo-environmental
parameters, 3) increased use of geophysical methods
for monitoring of changes in material properties
(and ground water properties) in space and time and
4) the impact of powerful electronic and computer
technology on field measurements, data analysis and
presentation.
INCORPORATION OF GEOPHYSICAL
SENSORS IN CPT
Extensive research during the recent decade,
especially in the area of geo-environmental
engineering, has lead to the development of new,
sophisticated field testing devices, notably
variations of the standardized cone penetrometer.
Research is also being carried out in order to
investigate the application of new sensors, which
can be incorporated in the CPT. Examples are new
laser-type and fiber-optical sensors, high-resolution
ground-penetrating radar antennas and integrated
opto-electronic chemical sensors, Robertson et al.
(1998). It is interesting to note that the CPT has
evolved from a standardized geotechnical
investigation tool into a multi-purpose testing
instrument.
The CPT as a multi-purpose instrument offers new
possibilities to compare in the same location (and
borehole) measurements obtained by a variety of
sensors. It will thus become easier to establish more