Benoît Jones reviews the most recent addition to the Taylor... Geotechnics.

Benoît Jones reviews the most recent addition to the Taylor and Francis series on Applied
Introduction to Tunnel Construction
By David Chapman, Nicole Metje and Alfred Stärk
This book ‘seeks to provide an introduction to tunnel construction for people who have little
experience of the subject’. It is intended as a comprehensive introduction for undergraduates who
are intrigued by tunnelling or recent graduates who have by luck or wit found themselves working in
the tunnelling industry. The book does not skimp on useful diagrams and photographs that
communicate the excitement of tunnelling and is thorough in its treatment of ground improvement
techniques, tunnel lining systems and tunnel construction methods.
The 390 pages are divided into eight chapters. The first (the introduction) begins with a brief foray
into the philosophy of tunnelling, emphasising the fact that, unlike many other civil engineering
structures, the ground is a major part of the structure, with both a supporting and a loading role.
Due to the many uncertainties involved, not just theory but the use of observation and experience
are required. After clarifying the scope, there is then a brief dash through the history of tunnelling
and an explanation of ground and tunnel terminology.
The next two chapters, ‘Site investigation’ and ‘Preliminary analyses for the tunnel’, are necessarily
quite short. However, although the use of site investigation to characterise the geology is adequately
covered at a basic level there is no mention of hydrogeology or the use of piezometers to determine
the groundwater pressures. As this is often critical to the selection of the construction method, it
should be given more prominence. ‘Preliminary analyses for the tunnel’ outlines several simple
calculation methods for stability and the dimensioning of support. This chapter is not intended to be
comprehensive but at times definitions are imprecise and the assumptions are not stated. However,
the chapter does serve to illustrate how tunnels work as structures interacting with the ground
around them.
The fourth and fifth chapters form the heart of the book where the enthusiasm of the authors really
shines through and I would almost recommend they be read first (particularly as there is a photo of
me in Figure???). Chapter 4, ‘Ground improvement techniques and lining systems’, covers a broad
range of ground improvement techniques such as ground freezing and various methods of improving
the ground using grouting in both soil and rock. Then various ground mass reinforcing elements are
dealt with including rock bolts, anchors, face dowels and roof pipe umbrellas before moving onto
compensation grouting and the use of compressed air. The second half of the chapter describes
tunnel lining systems, first outlining some of the design issues. The section on sprayed concrete
refers the reader repeatedly to Alun Thomas’s book (volume 2 of the Applied Geotechnics series),
which was reviewed by Barry New in the last issue of Tunnelling Journal. Segmental linings come
next and a useful table provided by Mike King explains the advantages and disadvantages of
segmental linings made from different materials. Waterproofing, shaft lining by underpinning and
caisson-sinking, in situ concrete linings and fire resistance complete the chapter.
As might be expected, the fifth chapter entitled ‘Tunnel construction techniques’ is by far the
longest, weighing in at 116 pages. There are rakes of clear diagrams and well-chosen photographs,
which really give a sense of the scale and variety of tunnelling projects and will certainly inspire and
enthuse the target audience. Even experienced tunnel engineers, unless they have worked in every
type of tunnel ever built, will learn something from this chapter. Timber headings, myriad TBMs, drill
and blast, sprayed concrete, cut and cover, immersed tube, jacked box, pipe-jacking, microtunnelling
and horizontal directional drilling are all covered.
The section on NATM and SCL in chapter 5 is of particular interest, and the authors manage to
explain the history and usage of the terms very clearly. The name ‘New Austrian Tunnelling Method’
was introduced to differentiate it from the ‘Austrian Method’, which was a timbering support
method followed by late installation of a thick brick arch lining. The NATM was revolutionary in that
it sought to use the early installation of anchors and a sprayed concrete lining providing intimate
contact with the ground, together with early ring closure, to prevent the development of ‘loosening
pressures’ arising from excessive deformation. A common misunderstanding of the NATM surrounds
the concept of activating a ground arch by allowing ground deformation to occur, when by far the
most important principle is that of preservation of the ground’s ability to support itself through early
installation of support. Professor Rokahr (to whom this book is dedicated) explained this excellently
in his seminal paper ‘Wie Sicher ist die NÖT?’ (‘How safe is the NATM?’) in 1995.
Chapter 6, on ‘Health and safety, and risk management in tunnelling’ by Donald Lamont is wellwritten and concise, with well-chosen references for further reading.
‘Ground movements and monitoring’ are the subject of chapter 7. This is more akin to a state-of-theart review that engineers of all levels of experience will find useful. The authors clearly have much
expertise in this area and communicate this with precision and style. A lot of space is given to the
principle of the ‘stress intensity index’, a method of determining the factor of safety of a sprayed
concrete lining from tunnel displacement monitoring developed at the University of Hanover.
However, since textbooks of this kind are usually read uncritically by their target audience, the
authors should have mentioned the potential for errors in this method, the existence of other backcalculation methods and the possibility of using strain gauges or pressure cells instead.
The final chapter details three case histories of the Egge tunnel in Germany, the Piccadilly Line
Extension Junction at Heathrow Terminal 5 in the UK and the Lainzer tunnel in Austria. These give a
flavour of how tunnelling challenges can be overcome by good engineering; through the use of
observation, experience, practical knowledge and theory. This is the theme which runs throughout
the book.
This book will be an excellent introduction to tunnel construction for all those new recruits who will
be needed when the workload increases over the next few years.