Basic HTML Version
28
Geotechnical News • December 2012
www.geotechnicalnews.com
GEOTECHNICAL INSTRUMENTATION NEWS
of these somewhat complex methods
runs the risk of a person being carried
away by the excitement of innovation
while ignoring the above words of
wisdom.
In what follows I will try to give some
suggestions applicable to “doing well”
with these seven methods for remote
monitoring of deformation.
First, the main advantages and limita-
tions of each method are summarized
in Figure 3, thus identifying the main
opportunities offered by the methods,
but also providing an understanding
of constrains. For example, if you are
looking for a short time 3D monitoring
of deformation at a specific location
with high data sampling frequency, it
can be seen that SInSAR is not suit-
able, while RTS is more appropriate. If
you are interested in monitoring past
deformations of a large area with high
accuracy, you can see that SInSAR is
probably the only available method.
Focusing on the geotechnical appli-
cations is more difficult, since the
number of cases to be considered is
very wide, and each one is likely to be
characterized by specific site condi-
tions that require a unique evalua-
tion. However, the following general
applications are identified below and
in Figure 4.
• Slope instabilities
: monitoring of
unstable slopes for both investigat-
ing purposes and continuous con-
trol.
• Tunneling in urban areas
: moni-
toring of local deformation induced
by underground excavation.
• Fluid extraction and pumping
:
monitoring of topographic changes
related to fluid or gas extraction
variation both at local and regional
scale.
• Quarries and mines
: real time mon-
itoring of slope instabilities during
mines exploitation.
• Dams:
monitoring of dams defor-
mation for testing and control pur-
poses.
• Heritage structures:
monitoring
of high value cultural heritage for
safety purposes.
• Civil buildings:
monitoring of stan-
dard buildings for safety purposes.
To emphasize with rating provided in
Figure 4 is appropriate only for ‘stan-
dard’ applications. The suggestions
are not applicable for ‘non-standard’
applications, where only a specific and
advanced design can provide the best
solution. For example, for the periodic
monitoring of fast-moving landslides,
DP or TLS can be more appropri-
ate than TInSAR and other methods,
while for the real-time monitoring of
localized subsidence related to fluid
extraction, TInSAR can be more
appropriate than SInSAR (thus contra-
dicting Figure 4).
Figure 4. Qualitative evaluation of the performance offered by all the remote methods for different geotechnical appli-
cations. From red color to green color (see at the scale bar) there is an increasing performance of the method.
Conclusions
Methods for remote monitoring of
deformation are gaining popularity
within the geotechnical commu-
nity because they offer several new
opportunities. Sometimes they can
be alternatives to traditional contact
methods, but more frequently they
can be integrated with them. They are
also opening new opportunities in the
geotechnical field, such as monitoring
for “investigative purposes. Features