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Geotechnik - Tunnelbau undTunnelmechanik
Tunnelling:
Management by Design
Kolymbas, D.: Geotechnik - Tunnelbau undTunnelmechanik,
Springer-Verlag, Berlin, Heidelberg1998, ISBN 3-540-62805-3, Price:
DM 128.00Muir Wood, A.: Tunnelling: Management by design,E&FN
SPON London and New York 2000,ISBN 0-419-23200- 1. Price: 40.00
Reviewing together two recently published engineeringbooks on
the same topic offers a welcome opportunityfor comparisons. If such
books are representative of themain currents of thought in their
field, such a doublereview is especially appealing.For decades
there has been growing competition toconventional tunnelling from
the so-called New AustrianTunnelling Method (NATM). The resulting
split in thetunnelling community was recently aptly characterisedby
A. Haack, President of ITA: Some regard NATM as acure-all drug and
a philosophy, others regard it as apseudo-scientific way of
thinking (Tunnel 7/97).Muir Wood's book stands in the tradition of
sound
scientific methodology; that of Kolymbas is a fruit of theNATM
ideology. The only thing the two works have incommon is a length of
around 300 pages. Muir Woodendeavours to communicate his rich
experience, gainedover a period of more than 40 years, to the
profession,bringing in scientific aspects (among other things in
theplanning and execution of the Eurotunnel) wherenecessary. In
doing this he can draw examples fromnumerous valuable publications.
Kolymbas main aim onthe other hand is, in his own words, to provide
themissing theoretical foundation of NATM'. To fulfil thistask -
due to the pseudo-scientific nature of NATM -neither practical
experience in tunnelling nor recourse to
one's own research work is necessary. In fact, in hiswork
Kolymbas does not refer to a single scientificcontribution of his
own or to any construction project inwhich he was personally
involved. What this leads to willbe illustrated by some examples.
First, his approximateformulas, which are intended to explain the
principles ofNATM, are based on unrealistic assumptions
onlyresulting in an inappropriate and unacceptablemathematical
formalisation of tunnelling. It suffices hereto mention his formula
for determining the required liningresistance when using a system
of grid anchors, inwhich he does not consider the influence of
rockdeformation. In this way he not only causes
embarrassment to the proponents of NATM, but alsocontradicts
himself, since in a previous chapter herecommends the method of the
characteristic line, whichtakes into account the deformation of the
rock todetermine the lining resistance. The
trough-shapedcharacteristic line proposed by Pacher represents
according to Mller the fundamental concept of NATM'.Kolymbas
deals with it in great detail. This in a way isunderstandable,
because the NATM literature listsnumerous practical examples for
the alleged use of thePacher curve to optimise the rock pressure
(TauernTunnel, Arlberg Tunnel, Tarbela Project, UndergroundPower
House Waldeck, etc.). In Kolymbas's opinion:in order to get by with
as low a lining resistance aspossible, the characteristic line of
the lining shouldintersect at point B (minimum of the ground
responsecurve) with the ground response curve. This NATMrequirement
is directed more to the intuition of thetunnelling engineer, from
which - strictly speaking - the
idea of the rising branch of the ground response curvecomes,
since the position of this minimum cannot bedetermined. The rising
branch appears to be veryplausible, but could not be verified up to
now either bymeasurements or by numerical simulation.Kolymbas is
perhaps unaware that with this statementhe has made the
protagonists of NATM (includingRabcewicz and Mller, who over a
period of decadesreported on concrete applications of the Pacher
curve)guilty of scientific fraud. Since he cannot produce eitheran
empirical or theoretical explanation for the basicconcept and
nevertheless claims it is reasonable, herelegates NATM to the
realms of fantasy.
How far the author is removed from the realities ofunderground
construction is shown in the followingexamples: Short anchors are
relatively expensive, sincethe most expensive part is the anchor
head. Thus a 24m anchor only costs about twice that of a 3 m
anchor.He forgets the costs for drilling the borehole andinserting
the anchor. The schematic representation ofthe method of action of
slit-rod-and-wedge type of bolts(Fig. 10.3) or the explanation of
the kerf cutting in therock by the disc cutter (Fig. 11.1) is
basically incorrect.
Also we consider his newly created term tunnelmechanics to be
superfluous, for after all, appliedmechanics has been associated
with tunnelling for all of
200 years. We now turn to Muir Wood's book. Theauthor's goal is
to present tunnelling in a systematic wayand he places his emphasis
on the explanation of theprocesses, which during planning, design
and executionalways occur in a variety of ways, changing from
projectto project. Accordingly, he begins his work with an
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explanation of the term 'system engineering and pointsout the
frequent differentiation in industry betweenproduct design and
process design (i.e. providing themeans of manufacturing the
desired product). As aresult he does not get bogged down in
abstractmanagement theory, but fills in the theoretical
frameworkwith expert knowledge, which is ordered and
weightedaccording to practical criteria. Numerous examples
ofsuccessful and less successful projects in manycountries clarify
the main points of his discussion. We
know of no other textbook on tunnelling with acomparably large
breadth of treatment, beginning with abrief historical
introduction, among other topics he dealswith the questions of
preliminary planning, financing,contract procedures, site
investigations, risks includingtheir distribution, design,
execution, geotechnical controlmeasurements as well as project
management. Whatimpresses the reader most of all is the rich
interplaybetween all these problem areas; in particular
thematicinteraction in the different phases of the realisation
ofprojects involving underground construction is difficult
topresent in a generally valid way. Muir Wood hasachieved this in
an excellent manner, because he has
not only directed many projects, but can also look backon an
extremely active International professional life: Sir
Alan Muir Wood, as is well known, was the firstpresident of the
international Tunnelling Association(ITA). A further special
condition which has favourablyinfluenced the coming into being of
his work, hesummarises as follows: The immediate spur to
writingthis book is that the author has lived and worked througha
period of revolutionary change in tunnelling withseveral
components.The concise presentation of the demanding
topicspresupposes that the reader possesses considerablebasic
knowledge and experience in tunnelling. The
formulations are very pregnant, so that perhaps thereader - like
the reviewer - has continually to write downsentences, which he
does want to forget. Forprofessional colleagues on the Continent
the soberBritish pragmatism, for which Muir Wood is anoutstanding
example, will definitely stand out positively.Thus he does not
leave the reader with the falseimpression of a perfect world of
tunnelling - on thecontrary, e.g. when reappraising the events
andanalysing the damage following the collapse of theHeathrow
Airport Tunnel in London. This chapter of hisbook, as every other,
is prefaced by a quotation, whichthose who know the background
details will find veryapposite: The curious incident of the dog in
thenighttime. The dog did nothing in the nighttime. That wasthe
curious incident (A. Conan Doyle).Hardly any reviewed work is not
thought to be in need ofsuggestions for improvement. Thus we think
that theshort section on analytical computational solutions as
anaid to design and construction seems to be alien to therest of
the text in which the author helpfully describesthe overall
behaviour of the ground; this is particularlytrue for the stress
state in the vicinity of a sphericalopening. Thus in the next
edition, chapter 8, devoted tothe topic of Hazards, Disputes and
Resolution, could bedealt with more explicitly. K. Kovri,
Zurich/CH
