Geotechnical News June 2011
21
GEOTECHNICAL INSTRUMENTATION NEWS
Geotechnical Instrumentation News
John Dunnicliff
Introduction
This is the sixty-sixth episode of GIN.
Two articles this time, and three more
one-pagers about web-based data
management software.
On My Soapbox
I’m returning to a favorite topic—
who should be responsible for
monitoring and instrumentation during
construction? By this I mean the tasks
of buying and installing instruments,
and collecting and interpreting data. As
I’ve claimed many times, if significant
decisions are to be based on the
monitoring data, it is imperative that
data quality is maximized. I contend
that these four tasks should
NOT
be assigned to general construction
contractors on a low-bid basis because
they may not have the greatest interest
in ensuring maximum quality. My
following article gives four specific
reasons for assigning responsibility for
these tasks to personnel selected by the
project owner or designer and under
direct contract with the project owner.
I appreciate that, when considering
most readers of GIN, I’m preaching to
the converted. But we need to do all
we can to get this message to owners
(and project managers in design firms,
who supposedly have the owner’s in-
terests at heart) that it’s in their interest
to adopt the recommendations in the
article.
Displacement Monitoring by
Terrestrial SAR Interferometry
New techniques are being developed
for monitoring displacement without
use of traditional geotechnical
instrumentation. One of these is
terrestrial synthetic aperture radar
interferometry. Here’s an article by a
colleague from Italy.
The companies listed in Table 1
provide terrestrial SAR interferometry
services. If you know of others, please
tell me.
Table 1. Companies providing
terrestrial SAR interferometry
services
Company Name
and Country
Website
Aresys S.r.l., Italy
IMG S.r.l., Italy
.
com
NHAZCA S.r.l.,
Italy
.
com
I hope to have other articles about new
remote techniques in future GINs, such
as:
• Satellite synthetic aperture radar in-
terferometry
• Robotic total station able to moni-
tor surfaces such as asphalt and
concrete, using a reflectorless dis-
tancemeter.
• Airborne laser scanning by Lidar
(Light Detection and Ranging)
Web-based Data Management
Software
David Cook’s article “Fundamentals of
Instrumentation Geotechnical Database
Management – Things to Consider”
was in December 2010 GIN, pp 25-28.
March 2011 GIN, pp 34-40, included
seven one-page articles by suppliers of
the software. Here are three more, by
Durham Geo Slope Indicator, Roctest
and Soldata.
Rick Monroe of Durham Geo Slope
Indicator, whose article about their At-
las web-based data management soft-
ware is on page 31, has sent me the
following additional valuable recom-
mendation, about response time:
David Cook defined response time
as the delay between data collection
and data presentation. Suppose we
collect a reading, send it to the In-
ternet via our cell phone, and then
see a graph about five seconds later.
That would be a response time of
five seconds. Granted, David Cook
was thinking about software, but
that definition misses an important
parameter: frequency of reading.
Suppose we visit the site just once
a week. Is five-seconds a still a rel-
evant measure of response time?
Let’s change the definition to “Re-
sponse time is the delay between
the occurrence of an event and the
monitoring system’s first report of
the event”.
Now take a common scenario: in-
place inclinometers are connected
New Website for GIN
The new website is www.
g e o t e c h n i c a l n e w s . c o m /
instrumentation_news.php. It has
an index of GIN articles that are on
the web, 83 downloadable articles,
and guidelines on how to submit
articles to me for future GINs.
