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Geotechnical News December 2011
GEOTECHNICAL INSTRUMENTATION NEWS
Book Review
Monitoring Underground Con-
struction. A Practice Guide.
British Tunnelling Society.
Review by John Dunnicliff
The guide has been prepared this
year by the British Tunnelling
Society subcommittee for monitoring
underground construction. Committee
members consist of engineers in
privately owned consulting firms,
in construction contractors and in
public agencies, with peer reviewers
from similar organizations.
It is intended for clients, project
managers, designers and construction
contractors, and “may also be relevant
to other parties such as insurers and ad-
jacent infrastructure owners who have
interests in underground construction
work”. Very sensibly: “The guide is
not intended to be prescriptive in terms
of detail design, which is recognised to
change relatively rapidly with advanc-
ing technology.” Hardware and soft-
ware are not covered. Watch this space!
The guide has the following chap-
ters:
Objectives of Monitoring
This has a crisp listing of why we
monitor underground construction,
including design verification, QA,
risk and liability allocation and asset
protection. The listing can be useful
for geotechnical designers when they
try to convince their project managers
and owners that monitoring can have
substantial technical and economic
value. In this context, readers of GIN
should also become familiar with Allen
Marr’s article in December 2009 GIN,
“Reasons for Monitoring Performance
with Geotechnical Instrumentation.”
( www. g e o t e c h n i c a l n ew s . c om /
instrumentation_news.php).
Marr
makes the following powerful
statement: “In general, a common
feature of these technical reasons is that
monitoring programs save money”.
Principles for Planning Effec-
tive Monitoring Systems
This chapter begins: “It is essential that
the objectives of a monitoring system
are clearly understood early in the life
of a project. This chapter addresses the
main actions which are necessary to
discharge the obligations to the client. ”
Designing Effective Monitoring
Systems
The principal target audience for
this chapter is those who specify
and design monitoring systems.
The chapter covers the distribution
of monitoring; accuracy, precision
and range; monitoring frequency;
baseline measurements; redundancy;
maintenance;
data
processing,
interpretation and review, presentation
and archiving; and requirements for
responses to monitoring.
Operation and Management
The chapter makes recommendations
for roles and responsibilities of
the various parties involved with
monitoring, including trigger levels
(also known as response values and
hazard warning levels) and contingency
plans.
Appendices
Appendices include:
• Valuable practical check-lists for
design of monitoring systems, re-
quired outputs, maintainability, op-
eration and management.
• Common monitoring problems ex-
perienced on previous projects,
with likely root causes. Fascinating
reading!
Summary Opinion of Reviewer
In my view this is an extremely
practical and valuable publication.
The text is direct and crisp, the
layout clear and readable. Because
this is a British publication, and
because this review is primarily for
a North American audience, a fair
question is, “Is it relevant to the North
American underground construction
community?” Yes, yes, yes. In fact,
much the content is relevant to all other
types of geotechnical construction for
which monitoring may be of value. As
Ralph Peck wrote in 1983:
The legitimate uses of instrumenta-
tion are so many, and the questions
that instrumentation and observa-
tion can answer so vital, that we
should not risk discrediting their
value by using them inappropriately
or unnecessarily.
Over the years I’ve seen many mis-
uses of instrumentation and monitor-
ing, and Peck’s words are so very true
today. This guide, if used wisely by
those who have a stake in monitoring,
should go a long way towards ensuring
that monitoring is used appropriately
and necessarily.
But don’t go—I have something
else to say that’s not so complimentary.
Regular readers of GIN will know my
focus on trying to ensure that in order
to maximize the quality of monitoring
data, monitoring and instrumentation
should not be subjected to the low-bid
process (often by principal/general
contractors requiring potential sub-
contractors to cut their charges to the
bone). In June 2011 GIN (same web-
site as for Allen Marr’s article above)
there is an article with the title “Who
should be responsible for monitoring
and instrumentation during construc-
tion?” The answer is:
The people who
have the greatest interest in the data.
Or put another way, who has the mo-
tivation to do these nit-picking tasks
with enough care? This can rarely be
achieved by cutting charges to the
bone. As indicated above, the guide
has a chapter on operation and man-
agement, and the chapter on principles
for planning refers to “the need to es-
tablish … a competent team”, but the
vital topic of recommending contrac-
tual arrangements isn’t there. In my ex-
perience, failure to deal with this issue
wisely is the most common “root cause
for monitoring problems experienced
on previous projects”. I find this omis-
sion very disappointing.
Reference for the Guide
ISBN 978-0-7277-4118-9. Orders can
be placed through
shop.com or by emailing orders@
pssc.com.
