Geotechnical News • June 2012
37
THE GROUT LINE
was focused on that portion of the data
measured by the computer systems
monitoring the grout injections. So, let
us turn our attention to how we make
these measurements.
Computer data acquisition and
monitoring is a rather well-established
technology (Ref. 12 is a convenient
briefing for grouters). The discussion
between various grouting groups on
“what” to measure is irrelevant as
modern computing systems can mea-
sure many more parameters than any
grouter will ever need. It is trivial to
have eight channels of data. The mini-
mum data suite only uses five: time,
pressure, flowrate, volume injected,
grout rheology (or mix indicator).
However, the appropriate data acquisi-
tion strategy in terms of scanning
rate, filtering procedures etc. has been
neglected with no industry consensus
on “how” to monitor. A computer
systems engineer might be horrified
with what we are all doing. From a
grouting perspective, the most chal-
lenging measurement issue is reliably
detecting hydrojacking, a process
that can initiate in seconds because of
the pressure-storage within the grout
delivery system. And,
this need sug-
gests a minimum standard of filtering
at 1 Hz for noise, with a matching 4
Hz scan rate; higher frequencies are
fine, but also result in larger files than
needed to understand what is going
on (inconvenient, but not a “deal
breaker”).
Data storage format is open to choices,
and a proprietary (i.e. binary) format
could be used. But, a binary format
would be a poor choice as file size is
small for grouting records, and the
gain from reduced storage in binary
format is completely offset because
the data can no longer be inspected
with a text editor. By far the best
choice is a text format complying
with the American Standard Code for
Information Interchange (i.e. ASCII
files). ASCII files are readily imported
into Excel for analysis, and are a basic
format in any high-level program-
ming language if writing proprietary
(custom) software. There is no reason
to not use an ASCII format, ideally
“comma separated values” (csv), and
every reason to so do.
Where proprietary software becomes
more of a consideration is with the
real-time display. With some systems,
a high-level “building block” language
is used (e.g. National Instrument’s
DASYlab) and it is not difficult to
add or change the display used on the
monitoring computer. Conversely, if
the display has been programmed in
C++ language changing the display
format may be challenging. This
points to the need for grouting indus-
try standards, but standards won’t
develop until we have a consensus
on the appropriate plots to be used –
and, as an industry, we are some way
off from that realization as discussed
earlier. Practically, this may not matter
in the short term provided the engi-
neering team can bring up the data
in Excel for further processing and
display.
Final comments and a question
This essay was triggered by a ruckus
over proprietary monitoring of grout-
ing. But if we accept that the New
Orleans conferences represent the
Industry’s view of what is appropri-
ate, then the companies offering
proprietary systems must address
the question: Why should aspects
others grouters in the industry con-
sider important be excluded by their
“proprietary” system? Or as one of the
participants at the Conference inquired
“What do they want to hide?”
In reality, “proprietary” systems
seem focused on ‘job-control’ rather
than ‘engineering-of-adequacy’, and
owners could live with such propri-
etary systems provided data can be
exported for Principle 2 assessment.
However, there is a caution too for
such proprietary systems – it is not for
the proponents of proprietary systems
to determine what is adequate. That is
the task of the owners engineers and
consultants, and industry-consensus.
And if that consensus requires aspects
not in proprietary systems, then those
systems must be modified to comply
with industry standards.
And a final request; open discussion is
the way we all learn. Real time com-
puter monitoring has proven advanta-
geous in managing and controlling
grouting work, and its use will only
increase over time. Original data is
often provided in standard format by
quality contractors. It is essential that
all grouting professionals are aware
of its advantages, disadvantages,
limitations, and all things related.
The authors strongly hope this essay
will be the beginning of ample and
thoughtful discussion (pro and con) of
the subject. Be it a few sentence opin-
ion, or a comprehensive article, send
your comments to the Grout Line!
References
1. Kaeck, W. E., Rhyner, F. C., and
Warner, J, (2012). Engineering and
design for deep foundation creep
and grouting at the Thames River
Bridge. Proc. 4
th
International
Conference on Grouting and Deep
Mixing, New Orleans, 2012.
2. Jefferies, M.G., Rogers, B.T. and
Reades, D.W. (1982). Electronic
monitoring of grouting. Proc.
Specialty Conference on Grouting
in Geotechnical Engineering, New
Orleans. Vol. 1, pp.769-780.
3. Lombardi, G. and Deere, D.U.
(1993). Grouting design and con-
trol using the GIN principle. Water
Power & Dam Construction, pp.
15-22.
4. Lombardi, G. (2003). Grouting
or rock masses. Proc. 3
th
Interna-
tional Conference on Grouting and
Ground Treatment, New Orleans,
pp. 164 - 197.
5. Carter, T.G., Dershowitz, W.,
Shuttle, D.A., and Jefferies, M.
G. (2012). Improved methods of
design for grouting fractured rock.
Proc. 4
th
International Conference
on Grouting and Deep Mixing,
New Orleans, 2012.
