Guideiines for the Design of Tunnels

YRE REPORT
~_
Guideiines for the Design of Tunnels
ITA Working Group on Genera! Approaches to the Design of Tunnels
Abstract-e- This ,e(Grui report bv thr ITA Warkmg- Group On (~eneral
.ipproaches
to th« Drsuin or Tunnels presents IrllernatlOl1a! desHUl
CTround
procedures
iot tunnels.
In most tW1nt'lIzrzç proterts.
actiuel» pcructpates
In prooiding stabilitv to
openmg-. T heretore,
t he urnerai
approach
la the desIgn
o! tunnels
includes
site
i.Ilvestl,;;atwns. ground prooines and in-situ mO/uIoTln,;;, as ue]! as
he ana/vszs oi stresses and deiormntions,
For the latter, the ditierent
.tructural
desz,;;n models'
apolied
at present-s-including
the
obseruationai
method-e-are presented. Guidelines lar the structural
ol the tunnel Immg and natzonal recommendalzons
on
.ieuuline
,,,mze! design are aiso gn'en. ft Is hoped that the mlormatlOn herrin,
based 011 expertences [rom a unde range of tunnel/mg- provects. uull be
-tissemrnated la tunnel designers throughout
ihe world.
rr
1 , Scope of the Guidelines
he International
Tunnelling
Associauon
(ITA)
\Vorking Group on General Approaches to the Design
,
of Tunnels was established in 1978. As its Iirst project,
the group developed aquestionnaire
aimed at compiling
inforrnation
about structural design models used in different
countries for tunnels eenstrucred prior to 1980. A synopsis of
rhe answers to the questionnaire
was published
bv the
International
Tunnelling
Association in ]982 (ITA ]982).
As a continuation
of that Iirst report, the working group
herein presents guidelines
that atternpt to condense
the
varrous answers from the first report and include additional
experiences in the general approaches to the design ol tunnel
structures, These guidelines tulfill one of the rnain objectives
of the International
Tunnelling
Associauon,
namelv, to
disperse intermation
on underground
use and underground
llillllia.;nuctur,esth,roughom the world bv crossing national borders
F'l"'Î ,<I language harriers.
j hose iruerested in the subject of tunnel design should also
consult nuhlished reporisot other ITA work ing groups. e.g,
the recent IT,\ report on contractual
sharing of risk (see
Tijt/ST 3:2) and ITA recommendations
on mairnenance
of
runn-Is (see [:rUST 2:3). Furtherrnore,
a number of national
~Hld international
organizarions.
such as the International
Societv on Rock Meeharnes. have published
recornmendauons on related subjects, such as field measurernents
and
laboratorv
iesungs lor rock and ground.
Some ol these
publications
and reports are lisred in the Appendix.
In tunne llina, most otten the ground acuveiv partir ipates
in providinz
stahilitv ro the opening. Theretore. the design
procedure
lor tunnels.
as cornpared
10
aboveground
-trucrures. is much more dependent on such factors as the SHe
SI rnanon.
ihe
rharacter ist ics, and [he excavarion and
support rnerhods used. Recornrnendauons
on tunnel design
This report
IS
r diteti 0'11 Heinz
Duddeck.
Ammateur
o! the
Approaches
m (he Design of
ITA Warkmg
Group on (;meral
Hein:
Duddeck,
Techrucal
Tunnels.
Present
address:
Prof.
Braunschusrig,
[!mver.\!l1l ol Braunschwezg. Beethouenstrasse
5I.
Fed eral Reoublic of (;ermanv.
,,00
{(wl'ullmQ;
Pnmed
(Hlä
Hl (~i(';l.i
{'r:JnQ'1'ound
Hnt~Hn.
SplKt
j't-,f!'lmloU;'V,
Vol
No
pp. :"::57-2'i9. 19X~
I
Résumè-Le grouoe de tmvazi AITES SUf ie dimensionnemeni
des
tunnels presente ici .Ion deu xteme rapport. En rassemblant loutes
'lUl rtaient
accessibles
entre les pa»: :>IU i,
:nfol'matuJns,
dimens!071nement
des tunnels, nous espérons, que les expenences
gagnées sur beaucoup de protets des travaux souterrams seron/
propagèes dans tout Ie monde. Parce que Ie sol parucipe d'une grarui»
partie à iournir
des moyens
de stabilitè
pour des ouvertures
souterrames, des methodes de dlmenszonnement
comprennent
ausSI
hlen les inVestlgatlOns
sur Ie chantler. ies essais laboratolTes et la
surveIllance
pendant
Ie progres
du travai/ que l'analvse
des
contramles
et des detormations.
Concemant
ce dernzer ootnt, Jes
diitèrents et actuellement ~ppliqués
mode/es de dimenswnnement
y compris
auss!
la methode
d'obseroation,
sont prèsentès,
Recommendations
oous les details de revêtement
et queiou-,
recommandatlOns
natlOnaies sur Ie dimenswnnement
des tunnels
achèoent ce rapport.
naturaHy are lirnited with regard to their consistencv and
applicabilitv
because each tunnelling
project is àffected by
special features that must be considered
in the design.
Nevertheless, it is hoped that the general outline provided in
these guidelines, based on the experience gained hom manv
tunnelling
projects, may be of sorne help for these staTting a
project.
2. Outline of General Approaches
2.1. General Procedure in
Designing a Tunnel
Planning
participation
a tunnelling project requires the interdependenof the tollowing disciplines, at a minimum:
•
•
•
•
Geology.
Geotechnical
engineering.
Excavarion technology. e.g. machine tunnelling.
Design of the supporting
structural elements. induding;
long-term behavier of rnaterials.
• Coacracr principles and law,
Although
the experts in each of these disciplines
mav he
responsible
only for their specific area of know ledge, the
decision on the ma in design features should be the outcomeo[
the cooperative
iruegration
of all the disciplines.
Only ihus
can it be ensured rhat the project. in all its details, has been
developed in unitv, and nor as the consecuuve addition of the
separate work of each of the experts.
The basics doeurnerus lor tunnel design should inc!udeor
cover:
• The geologica!
report presenting
the resu irs ol the
geological and geophvsical survey.
!lil The hvdrogeological
report.
t> The geotechnical
report on site invesrigarions.
including
the interpretation
of the resu lts of site and laboratory tests
wirh respect to the tunnellins;
process, soi l and mek
classificarion.
etc.,
• Inforrnauon
on l ine, cross-secuon.
drainage,
and
structural elements afiecting later use of the tunnel.
!lH>«i· 779R SM UGO
Pl'f~pmon
+
Prrs,
,no
pa,
..
• Plans for and a description of the projeered excavauon or
driving procedure. including rhe different cross-secrions
reiated to different ground condinons.
• Design doeurneuts for the types of excavauon rnethods
and tunnel supports likely to he applied, considering,
e.g. excavation advance and face support (tvpes and
number of anchors. shotcrete strength, closure length,
ete.
• The program Ior the in-situ monitoring of the tunnel bv
field measurernents,
• The analvsis of stresses and deforrnations rfor unlined
tunnels as wel! as for single-er double-lined tunnels I. and
the dirnensioning of the tunnel support for intermediate
phases and final linings,
• The design tor waterproofing or drainage.
• Structural doeurnerus for the Iinal design of the tunnel
project. including the detailing,
• During and after the excavation, reports on the field
measurernents and interpretation of their results with
respect to the response of rhe ground and the structural
safety of the tunnel.
• Doc~mentation of the problems encountered during the
excavation and measures applied, e.g. strengthening the
ground or changing the projeered type of support. based
on monitoring resuits.
The above sequence of these basic doeurnenis also provides
the general outline of the design procedure.
2.2. Elements of the Structursl
Design Model for Tunnels
In planning, designing, analvsing and detailing a
structure, engineers promise that the structure wiJl neither
suffer structurally nor collapse during its projeered lifetirne,
Thus, rnodels of the realîry are necessarv for analvsis in order
to predier the behaviour of a tunnel during the excavation and
during its lifetime, Models are also needed for bidding on
projects,
The following main elements involved in the design
procedure are shown as a flow-chart in Fig. I:
(1) Geology and site inuestigations must confirm the line,
orientation, depth, etc.. of the opening, e.g. a cavern.
(2) Ground probing and soil or rock mechanics must be
aoplied to determine the ground characteristics, e.g. primary
stresses, soil or rock strength, Iaults, water conditions.
2.3. Different Approaches Basad on
Ground Conditions and Tunnelling Methods
The response of the ground to extavation of an opening can
vary widely. Based on the type of ground in which mnnelling
takes place. four principal types of tunneHing may be defined:
I) for cut-and-cover tunnelling, in most cases the ground
acts only passively as a dead load on a tunnel structure erected
like any aboveground engineering structure.
(2) In soft ground, immediate support must be provided by
a süH !ining (as. for example. in the case of shield-driven
tunnels with tubhings for ring support and pressurized slurry
Fer N aciual StaUlontv
·lnltnOWO sail/tiV ma1çm
F(gure 1. Design process (or tunnelling.
238
Tt·C'.;NELLlNG
AND .• )NDERGROUND
I
Experience end preliminar» estimates or calculations
are used to deterrnine the cross-senion required and the choice
of the excavation method er the tunnel driving machine to be
used, as well as the methods ot dewatering the ground and the
selection of the supporting structural elements,
(4) After steps IlH3) are completed, the tunnelling
engineer must derive, or even invent, a structural model. By
applving equilibrium and cornpatibility conditions to the
model. the engineer has to arrive at those criteria that are
factors in deciding whether or not the design is safe. Different
rnodels may be used for each excavation phase, Ior the
preliminarv and the Iinal tunnel lining, or for different
ground behaviour, e.g. in discontinuous rock or homogeneous soft soil. Modelling of the geometrie features rnav
varv greatlv, depending on the desired intensitv of the
analvsis.
f:;) A safety concept drawn hom failure hypotheses mav be
based on criteria such as strains, stresses, deformarion. or
Iailure modes.
The bypass in Fig. I indicates that for manv underground
structures, as in mining or in self-supporting hard rock. no
design models at all are applied, In such cases, past
experiences alone may he suffierent.
Risk assessment by the contractor as well as by the owner is
needed at the time of contract negotiarions. Risks involve
possible structural failures of the tunnel support and lining,
functional Iailures after completion of work, and Iinancial
risks. The contractual aspects also include risk sharing and
risk responsibilities.
In-situ monitoring can be applied only after the tunnelling
has begun, If the displacements stop increasing over time. it
generall y may be assumed that the structure is designed safe!y.
Yet monitoring provides onlv part of the answer to the
question of safety, Ior it does nor tell how close rhe structure
rnay be to sudden collapse or nonlinear failure modes. The
results of field rneasurements and experiences during
excavation may com pel the engineer to change the design
model by adjusting it to real behaviour,
An iterative, step-bv-step approach is characteristic of the
design of structures in the ground that ernplov the
participating strength of the ground (see loops in Fig. I). The
designer may begin by applving estimated and simple
behavioural models, Adjustments based on actual experiences
during rhe tunnelling excavation (such as excavating the
initial sectien in the same ground condinons or driving a
pilot tunnel) will bring the model doser to reality and refine ir
(if refinement is consistent with the overall accuracy
auainable). The interpretations of in-situ measurements (and
some back analyses) also rnav assist designers in making these
adjustments.
All of the elements of the structural design model in Fig. I
should be considered an interacting unitv, Scattering of
parameters or inaccuracv in one part of the model wiJl affect
the accuracv of the model as a whole. Therefore, the Same
degree of simplicity or refinemenr should be provided
consistentlv through all the elements of the design model. For
example, ft is inconsistent to apply very refined mathematical
tools simuitaneously
with rough guesses of important
groundcharaeteristics.
SPACE TECHNOLOGY
Volume 3, Number 3. 1988
lor tace support).
In such a case. the ground usuallv
providing resistance Hl outward
detorrnauon ot the lining,
i. j) In medium-hard
rock or in more cohesive soil, the
ground mav he streng enough to allow a eertam open secnon
at the tunnel face. Here. a eertam amount of stress release may
permanentlv he vaiid befere the supporting elements and the
lining
acting effectively, In th is siruation onlv a
fraction
the prirnarv ground pressure is acting on the
lininz.
i. .J:l···When tunnelling
in hard rock. ihe
alone mav
the stabilitv of the opening sa that onlv a th in
anv, wil! be necessarv for surface proteetion. The design
model must take imo account the rock around the tunnel in
order 1O predier and verify safety considerations and
deformations.
Especiallv in ground condirions that change along the
tunnel axis, the ground may he strengthened bv injections.
anchoring, draining. freezing, etc. Under these circumstances.
case (2) mav he irnproved, at least temporarilv, to case
The characteristic stress release at the tunnel face t Erdrnann
1983) is shown in Figs 2 and 3. The relative crown displacement w is pletred along the tunnel axis, where w/wo = l.0
represems the case of an unsupported tunnel. In mediumstift ground nearlv 80%of the deforrnations have already takent
place befere the lining (shown here as shotrrete) is stiff
enough
to participate.
O,ll
(1,2
______ ~.L
0,6 <,.0
\llIll1ll!1IlOdol
I without
/ stress '.iRst
0,&
1.0 w, ,wIIMut
t w/.,
il""'!lT-------L--r;;,o-
Figure 2. Crown displacement
bevond the tunnel face.
w
along the axis, ahead and
»l~Ol
olm ••
I
,
-lilt-
,;;
I"
GoorG~
\>
I
Fm a simpliiied plane model with na stress release, where
the Iull primary siresses are assurned to act on a lined opening,
ihe displacement mav be onlv 0.4 of that occurring in the
unsupported case. The corresponding stress release is shown
in Fig. 3. The simplified example, considering onlv the
constant part of radial pressure, yields the values shown for a
ring stiffness of EaA = 15.000xO.3 =4500 MN/m and a ground
deforrnation modulus of EK = 1000 M:'J/m2•
Even in the unrealistic case when the full primary stress acts
simultaneousiv on the ground opening and the lining, onlv
.">5%
of the stress is taken by the Iining: in the case of EBA
2250 MN/m, onlv 38% is taken by the lining. If an open
sectien of 0.25 of the tunnel diameter is left without lining
support. the iining takes onlv 25%of the primary stresses: Ior
Lr = 0.5 D, it takes only 12%of the primary stresses.
FOT very soft ground requiring immediate support (as in the
case of very shallow tunnels). almest 100%of the primary
stresses are acting on the lining, The values change, of course.
with other stiffness relationships and other stress distributions than these shown in Fig. 3, with other cross-sections.
and other tunnelling methods,
2.4. Site tnvestiqetions; Structursl
Analysis end In-Situ Monitoring
An adequate intensity of site exploration, from which
geological and hydrological mappings and ground profiles
are derived, is most important for choosing the appropriate
tunnel design and excavation rnethod. A well-documented
geological report should provide as much intermation as is
obtainable about the physical features along the tunnel axis
and in the adjacent ground, The amount of information
should be much greater than the inforrnation required Ior
entering directly into a structural analvsis.
The results of an analysis depend very rnuch on the
assurned model and the values of the significant parameters.
The main purposes of the structural analvsis are to provide
the design engineer with: (I) a better understanding of the
ground-structure
interaction induced by the tunnelling
process; (2) knowledge of what kinds of principal risks are
involved and where they are located: and (3) a tooi for
interpretating
the site observations and the in-situ
rneasurements,
The available mathematica 1methods of analysis are much
more refined than are the properties that constitute the
structural model. Hence, in most cases it is more appropriate
to investigate alternative possible properties of the model, or
even different models, than to aim for a more refined model.
FOT most cases. it is preferabie that the structural
model
ernploved and the parameters chosen Ior the analyses be
lower-Iimit cases that may prove that even for unfavourabl«
assurnptions, the tunnellieg process and the Iinal tunnel are
suffici:ffit!y safe. In general. the structural design model does
not trY to represent exactlv the verv actual condinons in the
tunnel. although it covers these conditions.
In-situ monitoring is important and should he an integral
part of the design procedure. especiallv in cases where
stahil ity of the tunnel depends on the ground properties.
Deformanons and displacemenrs generallvcan he measured
with much more accuracv than stresses. The geometrv of the
deformanons
Figure 3. Ground stresses acttng on the lining as fmetions of
Ihè pnmarv stress (Erdmann 1983J.
Volume 3. :'Jumber 3. 1988
and their development
over time are most
significant Ior the interpretanen
of the act ual events,
However, in-situ moniroring evaluates onlv the verv local and
acrua I situatiou in the tunnel. Therefore, in genera I the
condinons taken into account bv the design calculations do
not coincide with the condinons that are monitored. Only by
relaring rneasuremenr results and possible failure modes bv
extrapolaring can rhe engineer arrivé at considerations of
safety margins.
In many cases, exploratorv tunnelling may he rewarding
because of the inforrnation it vields on the actual response of
the ground to the proposed m~thods for drainage. excavation,
TI'NNELLlNG
AND UNDERGROt'ND
SPACE TECHNOLOGY
239
TBM drivinz. support. etc. In important cases a pilot tunnel
mav be driven: such a tunnel mav even be eniarged to the lul!
fin~l tunnel cross-secnon in the most representarive ground
along the tunnel axis, For Iarger projects, it rnav he useiul to
excavate a trial tunnel prior to commencing the actual work,
:VIoreintensive In-situ monitoring of the exploratory tunnel
sections should check the design approach by numerical
anaiysis.
2.5. Design Criteria and
Evaluating Structursl Safety
An underground structure may lose its serviceabilitv or its
structural safety in rhe following cases:
The structure loses its watertightness,
The deformations are intolerably large.
The tunnel is insufficiently durable for its projeered life
and use.
The material strength of the strucrural elements is
exhausted locally, necessitating repair.
The support rechnique (for exarnple, in erecting
segmental linings) fails or causes damage.
Exhaustion of rhe material strength of the system causes
structural failure, although the conesponding deformations develop in a restrained manner over time.
The tunnel collapses suddenlv because of instability.
The structural design model should yield criteria related to'
Iailure cases. against which the tunnel should be designed
safely. These criteria mav be:
•
•
•
•
•
Deforrnanons and strains.
Stresses and utilization of plasticiry.
Cross-sectional Iining failure,
Failure of ground or rock strength.
Limit-analysis Iailure modes.
In principle, me safety margins may be chosen differently Ior
each of the failure cases lisred above. However, in realitv the
evaluauon of me actual safety margins is most complex and
very much affected by the scattering of the involved properties
of the ground and the structure and, Iurthermore, by the
interacting probabilisnc characteristics of these properties.
Therefore, the results of any calculation should be subject to
crincal refleceion on their relevanee to the actual conditions.'
National codes for concrete or steel structures may not
always he appropriate for the design of tunnels and the
supporting elements, Computational
safetyevaluations
should alwavs he cornplemented
by overall safety
considerations and risk assessments employing crincal
engineering judgment, which may include the Iollowing
aspects:
• The ground characteristics should be considered in light
of their possible deviauons from average valnes.
• The design model itself and the values of parameters
shouid he discuseed bv the design team, whieh includes
all of the experts involved (see Secnon 2.1. "Ceneral
Procedure in Designing a Tunnel," above).
• Several and more simp Ie calculation
runs with
paramerrie variations may uacover rhe scattering of the
results. In general. this approach is much more
informative than a single over-refined investiganon.
• The in-situ measurements should he used for successive
adjustment of design models.
• Long-term measuremem of ddormations
via extrapoiation may reveal lO a large extent the final stabilitv ol
the struemre, although sudden collapse may not blO
announced in advance.
3. Site Investigations
and Ground Probings
3.1. GeoJogical Data and Ground Parameters
The appropriate amount of ground investigations on site
and in laboratories mav vary considerably from project 1O
2,10
TUNNELLlNG
AND
I 'NDERGROUND
SPAC.E TECHNOLOGY
Because the types of ground explorations and
probmgs depend on the special features of the tunnelling
project. its purpose. excavation rnethod, ere.. thev should he
chosen bv the expert team, especially in consultatien with the
design engineer. The intensitv of the ground explorations
wil] depend on the hornogeneirv of the ground, the purpose of
the tunnelling, rhe cost of boring, e.g, for shallow or deep
cover. and ether factors.
The geological investigations should include the following
basic geotechnical information (see also 15RM Commission
on Classification of Rocks and Rock Masses 1981).
3.1.1. Tunnels in rock
Zoning. The ground should he divided in geotechnical units
Ior which the design characteristics mav be considered
uniform. However, relevant characteristics rnav displav
considerable variations within a geotechnical unit. The
Iollowing aspects should be considered Ior the geological
descripnon of each zone:
• Name of the geological formation in accordance with a
genetic ciassification.
• Geologie structure and Iracruring of the rock mass with
strike and dip orientauons.
• Colour, texture and mineral cornposition,
• Degree of weathering,
Parameters of the rock mass e.g. in five classes of intervals.
including:
•
•
•
•
•
•
•
•
•
•
Thickness of the lavers.
Fracture intercept,
Rock classification,
Core recovery.
Uniaxial compressive strength of the rock. derived from
laboratory tests.
Angle of friction of the fractures (derived from laboratorv
direct shear tests).
Strength of me ground in on-site situations.
Deforrnation properties (modulus).
Effect of water on the rock quality.
Seismie velocity.
Primary stress field of the ground. For larger tunnel
projects, tests evaluating the natural stresses in the rock mass
may be recommended, For usual tunnel nroierts one shou kl
least estimate the stress ratto Oh! Cl" al ruunes ,cve" wnere Oh IS
the lateral ground pressure and (1" me major principal stress
(usuallv in the vertical direction), Ior which the weight of the
overlving rock generally may be taken. Teetonic ssresses
should be indicared.
Water conditions. Two types of inforrnation about water
condinons are required:
(I) Permeabilitv, as determined bv:
Coefficient k (mis) (from field tests).
Lugeon unit (from tests in boreholes),
(2) Water pressure:
At the tunnel level (hvdraulic head),
.tt piezometric levels in bereholes.
Deiormabilitv of the rock mass. In-situ tests are required ro
derive the two different deformation moduli. which can be
determined either from static medlods (dilatometer tests in
boreholes. plate tests in auits. or radial jacking tests in
chambers) or from dynamic methods (wave velocitv by
seismic-refraction or by geophysical logging in borehoies).
Engineering judgment should he exercised in ehoosing the
\'alue of ,he modulus most appropriate for the design-for
instance. oy .he relevant tangent of the pressur,e-dtef(Jrl1naition
curve ar the primary stress level in the statie method.
Propenieslor which information is needed when tunnel
boring machines are to he employed indude:
Abrasiveness and hardness.
Mineral composites. as, e.~. quartzite contents.
Homogeneity.
Volume 3. Number 3, 1988
Suielling potential of the rock. The présence of sultates,
hvdroxvdes, or
minerats should he nvesugated bv
rnineraloaical testing. A special odeometer test mar
used to
deterrnine the swell test-curve of a specimen subjeered first to a
load-unload-reload
cycle in a dry state. and then unloaded
with water.
The following ground water conditions should be given:
Water levels. piezometric levels. variations over time.
pore pressure measurements in confined aquifers.
Water chemisuv.
Water temperatures,
Expected amount of water inflow,
3.1.2. Tunnels in sml
The geotechnical description should primarilv follow the
recornmendations given above for rock. Additional special
features for wil include:
1. Soil identijication (laboratorv testing):
• Partiele size distribunon,
• Atterberg
•
•
•
•
Iimits
WI' wp'
Unit weights. ')I, "Id. 'Yl:.
Water content ur.
Permeabilitv k.
Core recovery.
2. Meehamcal properties determined bv laboratory testing:
• Friction angle dru, cP.
• Cohesion e", e.
• Compressibility Tnt" c.:
3. Meehaniea!:tJroperties deternined bv field testing:
• Shear strength Tl' (Vane-test).
• Penetration N (Standard Penetrasion Test).
• Deformabilitv E (Plate bearing, Dilatometer).
4. Ground water eondition (in addition to these liseed in
3.1.1.): permeability, as determined by pumping tests.
value or a value corresponding to a moderately conservative
fractile of a Caussian distribution is more appropriate than
the worst case value.
A set of all the parameters descrihing the ground behaviour
of one tunnel sectien with regard 10 tunnelling should he seen
as a comprehensive unit and should he well-balanced in
relation 10 each ofthe parameters. For example, a small val ue
of ground deîormation modulus indicates a tendency 10
plastic behaviour, to which corresponds a ratio of lateral to
vertical primarv stress that is closer to LD. Hence, Ior
alternative investigations some complete. balanced sets of
parameters shouid be chosen instead of considering each
parameter alone, unrelated to the ethers,
The available rnethods Ior ground prohing and laboratorv
tests, their applicabilitv and accuracv are given in the
Appendix.
3.3./nterpretation
of Test
Results end ûocumentetion
The field and laboratorv tests should be given in welldoeurnenred reports. in the form of actual results. Based on
these reports. an interpretation of the tests that is relevant to
the actual tunnelling process and the requirements of the
design models for Ihe structural analvsis is necessary. At the
time the tests are planned, the team of experts referred to in
Sectien 2.1 should decide which ground properties and
ground characterisucs
are necessary for the general
geotechnical descripuon of the ground and for the projeered
design model. Thus, a closer relationship mav be achieved
belween ground investigations and tunnelling design. and
between the amount and refinement of tests and the
tunnelling risks.
The doeurnerus should lay open the rationat interpretational way in which design values are derived from test
results. This method has proven 10 he especially useful in the
teadering process, because it condenses the relevant data for
the description of the ground and for the design of the tunnel
on a band along the tunnel axis beneath a graphical
representation of the runnel profile (see the examples in Figs
9-13).
3.2. Evaluation of Parameters by Ground
Probing en« Laboratory Tests
The properties of the ground that are relevant for the tunnel
design should be evaluated as carefully as possible, In-situ
tests. which cover larger ground rnasses, generally are more
significant than are laboratorv tests on srnall specimens.
which often are the better preserved parts of the coring. The
natural scattering of ground properties requires an
appropriate number of parallel tests-at least three tests for
each propertv (see also the cortesponding 15RM recornmendanons
l.
Results of laboratorv tests must be adjusted to site
conditions. The size of specimen, the effects of ground water,
the inhomogeneitv of the ground on site. and the effects of
scattering must he considered, The conclusions drawn from
tests also should take into consideration whether the
specimens were taken from distutbed or undisturbed ground.
In many cases, the first part of the runnelling may he
interprered as a large-seale test, the experiences from which
mav he drawn upon not only Ior the subsequent excavations
but also Ior prediering ground hehaviour. In certain cases,
long horizon tal boreholes may facilitate ground prohing
ahead of the face, or a pilot tunnel may serve as a test tunnel
that at the same time provides drainage. The on-site
investigations provide valuahle resuhs for checkillg the
correlation of
in-situ tests with laboratorv tests.
Special tests
correspond directly to the proposed
mnnelling method may oe required. e.g. lor the sufficiem
preservation of a membrane at the face of a hentonite shield.
The evaluation of the parameters should indicate lhe
expected scattering. From probabilistic consideratioll of
norma!ly dislributed quantities il ean he dedun'd that a mean
Volume 3. Number 3. 1988
Such condensed tables may be prepared Iirst for rendering
and the preliminarv design. and then improved through
experience gained and incoming monitoring
results,
However, it should be clearlv stated, especiallv in the contract
papers. that much relevant information
is lost or
oversirnplified in such tab les. and that therefore the
geotechnical reports and ether complete doeurneuts should be
considered the primary doeurneuts.
4. On Structural Design
Models for Tunnelling
4.1. Alternative Design Models
The ëxcavation of a tunnel changes the prirnarv stress field
into a rhree-dimensional pauern at the tunnelling race.
Farther from the face. the stress field eventuallv will return to
an essentiallv two-dimensional svstern. Therefore, the tunnel
design may consider only two-dimensional stress-stram Iields
as first approxirnations,
The design of a tunnel should take into account the
imeraction between ground and lining. In order to do so. the
lining must be placed in dosest possible hond with the
ground. To preserve Ïts nalural strength. Ihe ground should
he kept as undislurbed as possible. The deformations
restdting from Ihe tunnelling process (see Fig. 2) reduce lhe
primarv ground pressure and create stresses in the iining
eorresponding la that fractionai part of the primary stresses in
the ground which act on the suslaining lining. The stresses
depelld on the stiffness relationship of the ground lO the
Iining, as weil as on the shape of the tunnel cross-section. The
latter should he selected such that an arching anion in the
groundand the !ining may develop.
TiiNNELUNGAND
UNDERGROl1ND
SPACE TECHNOLOGY
2·11
{r.::\2 '
'\.V
empirical
approach
tt t~
.
::1$::1
-'+7--
mn mn
Gv
IGv=y
h
rrm rrm
Gv
Gv
Gh~$~
~m~~m~
~m~Gh
om [[[] om rrrn
Figure 4. Alternative
plane-strain
design models fOT different
Figure 4: presents Iour different structural rnodels for a
plane-strain design analysis, The cross-secrions need not be
circular. These Iour models are explained more explicitly
below.
In soft ground, irnmediate support is provided by a
relativelv stiH lining. For tunnels at shallow depth (as for
underground railways in cities) , it is agreed that a twodimensional cross-sectien may be considered, negleering the
three-dimensional stress release at the face of the tunnel
during excavation. In cases (I) and (2) in Fig. 4, the ground
pressures acting on the cross-sectien are assumed to be equal
to the prirnarv stresses in the undisturbed ground. Hence, it is
assumed that in the final state (some years alter the
construction of the tunnel), the ground eventuallv will return
to nearly the sarne condition as befere the tunnelling,
Changes in ground water levels, traffic vibrations, erc., mav
provoke .this "readjustment,"
In case ( I), for shallow tunnels and soft ground, the full
overburden is taken as laad. Hence, no rension bedding is
allowed at the crown of the tunnel. The ground reaction is
simplified by radial and tangenrial springs, arriving at a
bedded-beam model,
In case (2), for rnoderatelv stift ground, the soil stiffness is
ernploved by assuming a rwo-dirnensional continuurn model
and a complete bond between lining and ground. As in case
(I l, stress release due to predeformations of the ground is
neglected, Inward displacements result in a rednetion of the
pressure on the lining,
Case
assurnes that some stress release is caused
deforrnauons that occur befere the lining participates, In
medium-hard rock er in highlv cohesive soil, the ground mav
be streng enough 10 allow a certain unsupporred section al
rhe tunnel face (see Fig. 2). Also, for tunnels having a
overburden. a rednetion of the acting crown pressure
(represented in Fig. 4 bv h < H) is taken into account.
In case 141,the ground stresses acung on the lining are
determined bv an empirica! approach, which rnav he based on
previousexperiencee wirh the sarne ground and rhe same
tunnelling rnethod, on in-situ observations and monitoring
242
Tt';-';7'iE:LUNG
ANI) UNDERGROUND
SPACE TECHNOI.OGY
depths and ground stiitnesses.
of initial tunnel sections, 00 interpretation of the observed
data, and on continuous improvements of the design model.
If a plane model is not justitied-e-as is the case for caverns,
for more complicated geometries of underground structures,
or for an investigation directly at the tunnelling face-a threedimensional model may be necessary (see Fig. 5). The threedimensional model also may be conceived as consisring of
discontinuous masses (block theory) or a continuurn with
discrete discontinuous fissures or faults,
Q,
Figure 5a. Three-dimensional continuum model.
Figute 5b. Example of tuio-dimensional finite-element
model.
4,2. Continuurn or
Discontinuum Model
For structural design models such as those in Figs Sa and b,
the ground may he modelled as homogeneous
or
heterogeneous. isotropie or anisotropic: as a (WOdimensional, i.e, allowing some stress release befere the
lirnng is acting, or a three-dirnensional stiff medium. The
Iining may be modelled either as a beam element with
bending stiffness or as a continuurn. Plasticitv, viscosirv,
Iracture of the rock, non-Imear srress-strain and deforrnation
Volume 3, Nurnber 3, 1988
behaviour, etc., ma. be covered bv special assumptions for
material laws.
The design criteria are computed by numerical solutions,
Frorn rheir origins, the finite-element metbod and the
boundarv-element method are basically continuurn methods.
Thus, homogeneons media and stress-strara Iields are
evaluated best, In general. discontinua such as rock with
fissures and faults, and Iailure modes, which are initiared bv
local rupsure. shear failure, or full collapse, cannot be covered
bv connnuum rnethods.
A continuurn or discontinuurn model is appropriate for
tunnel structures where theground provides the principal
stability of the opening (as in hard rock) or where the
geometrical properties of the underground opening can be
modelled onlv by numerical analysis, e.g, in the case of dosely
spaeed twin tunnels.
4.3. 8edded-Beam Model
(Action-Reaction Model)
If the stiffness of the ground is smal! compared to the
stiffness of the lining, a design model such as that shown in
Fig. 6 may be emploved. In such a case, the active ground
pressures are represented by given loads and the passive
reaction of the ground against deformarions is simulated bv
model may he particularl~
constant bedding m~uli.
well-suited to the design af linings af shîeld-driven tunnels.
As to applicabilitv, the stiffness ratio 13 may be smaller than
200:
1?~
where:
13 = E.R3/E] < 200,
E.
is the representative deformation stiffness
modulus af the ground,
R is the radius of the tunnel cross-sectien or its
equivalent for non-eireular tunnels,
E] is the bending stiffness of the lining,
A more correct soletion for the bedding is given by a nonzero stiffness matrix for al! elements with regard to radial and
tangendal displacements,
However, in most cases and in view of the unavoidable
approximations based on the ether assumptions, a simpler
approach may be sufficient. Such an approach considers only
~dial (and, eventually, tangential) bedding, negleering the
interdependence of radial and tangenrial displacements and
beddings, For non-eireular cross-sections, the continuurn
solution reveals that bedding may be increased at corner
sections of the Iining, with smaller radius of the curvature.
The bedded-beam model may be adjusted to more complex
cases, e.g, by reducing the crown load in accordance with
stress release at the tunnel face (see Fig. 3) or, for deep tunnels,
by assuming bedding also at the crown.
For articulated effmive hinges in linings the bending
rnoments are smaller; the deîormations may be larger,
depending on rhe ground stiffness. For hinged linings the
limit of f3 given above is aot valid.
The analvsis of the bedded beam vields ring farces. bending
mo~e~ts, and d~formations as design criteria for the lining. If
the lining' rmg IS completely dosed, the bending momems
may he considered less important than the ring forces for
providing equilibrium (a smaller safety factor may be
fb''V·H
rt+rJ
a ~'f;
G"••
--r
I
8. Hi
4R
\j~~Gh
K,,'Gt:Î:tIJ
y
Kr"conlllt.
Gv
",volume w.igll1
radial
displ.
ground
reactien
Figure 6. Example of a bedded-beam
tunnels.
Volume 3, Number 3. 1988
hoop bending
momentlll
tere.!>
model for shaUow
w'j"" __
fJI$.
usion
streu t.!M".
E '_i!lwi
•••••
l1lld
ccntlfwity
Figure 7. C haracteristic curves [or the ground and the suppon
[or conuergence-coniinement models (Fenner-Pacher c~rves J.
justified Ior the bending rnoments). Allowances also may be
made for a plastic rotatien capacity of the Iining segrnents.
For tunnels with verv pronouneed stress release due to
inward deformations, e.g, Ior deep tunnels in rock, a simple
approach
to d~sign considerations
is given by the
convergence-confinement model, which is based only on the
int~ction of the radial inward dis placement and the support
reaenen to ~hesedeforrnations by resisting ring Iorces and the
cortesponding outward pressure (see Fig. 7).
The primary stresses (Jo in the ground are released with
progressive inward displacements. The acting pressure may
e~en mcrease when rock joints are opening with larger
displacements, In self-supporting rock, the ground characreristic in Fig. 7 meets the w-axis; because the primary
stresses are released completely, a supporting lining is not
necessary, Befere the supporting memhers are installed. it is
unavoidable-c-even desirable-i-raar decompression associated
with the predeforrnation Wo will oceur, The stiffness of the
lining determines where both curves (characteristic lines) wil!
interseet. At this point, equilibrium as weU as compatibilitv
condinons are fulfilled. If the ground characteristic is known,
e.g., by in-situ monitoring, rhe predeformation Wo and the
stiffness of the lining (including its development over time
and as tunnelling advances), and even its plastic properties
are veI')' de~isive for the actual stresses in the lining, Both
curves m Fig. 7 may vary considerably.
In its usual analytical form, the convergence-confinement
. model assumes constant ground pressure along a circular
tunn~llining. Consequently, ü yields only ring Ierces and no
bending moments at all. However, ie may be extended to cover
ground pressures that vary along the tunnel lining (Cesta
1986).
The model mayalso he applied as a first approximation Ior
non-~ircular tunnel cross-sections, although the support
reaenen curve is dîstinctlv different, e.g. for horseshoe-type
cross sections. Therefore. it may he helptul to use the
convergence-confinement
model in combination with a
contimmm model and in-situ rneasurements.
~lth?ugh
the convergence-confinement
approach
is
primarily a tooi Ior the interpretation of field rneasurements
it also may he applied in support of the empirica! approach:
4.4. Empirical Approach
The structural elemems :md the excavation procedure,
especially for the preiiminary support of the tunnel, may be
selected mainly based on experience and empirical
considerations that rdy more on direct observations than on
numerical ?llculations. This procedure may be especially
reasonahle af experiences from a successful tunnelling project
can be applied to a similar. new one yet to he designed. Such a
transier of information is justified only when:
• The ground conditions, including those of the ground
water, are comparable.
• The dimensions of the tunnel and ltS cross-sectional
shape are similar.
• The depths of overburden are approximately the same.
TUNNELLING
AND UNDERGROVND
SPACE TECHNOLOGY
243
• The runnellina methode to he emploved are the same,
• In-SItu rnonitorina yields results cornparable to those lor
the precedmg tunnelling project.
One disadvantage of prolonged application of the empirica!
approach is that, lacking an incentive to applv a more
appropriate
tunnelling
design via a consistent safety
assessmern, the structure may he designed overconservauvelv.
resulting in higher construction costs, The sirnple
approach coutributes little to the advancement of rhe state of
the art in tunnelling.
The ernpirical approach to tunnel design mav also be
applied to larger projects in only alightlv changing ground if
provision is made (especiallv in the tender) Ior initial
experiences to be extrapolated to the subsequent sections
along [he tunnel axis. Such a sinration jusrifies a
rneasurernent programme that is more intensive for the Iirst
sections, in order to gain experience,
4.5. Observational Method
By combining analvtical methods with the empirica!
approach and the immediate interpretations of in-situ
measurernenrs. a tunnelling design procedure that is
adjustable as the tunnel excavarion proceeds rnav be applied,
In this approach. the field rneasurements of ground
movements, displacements and stresses in the Iining are us~d
on an ongoing basis to verify or modifv the design of tfie
tunnel. More intensivelv instrumented sections at the early
stages of the tunnelling provide the data for these procedures.
The interpretation of the rneasured data vields insight into
the ground behaviour as areaction
to the tunneiling
procedure.
In applving the observational method, the following
condinons must be met:
• The chosen tunnelling process must be adjustable along
the tunnel Iine,
• Owner and contractor must agree in advance on
comractual arrangements that allow for modifications of
the design 00 an ongoing basis during the project.
• The field measurements should be interprered on the
basis of a suitable analvtical
concept relating
messurement data to design criteria.
• The interpretation of a partienlar instrumented sectien
must be used to draw conclusions abour the other
sections of the tunnel. Hence, the experiences are
restricted to these tunnel sections that are comparable
with respect to ground condinons. ground cover. etc. (see
Secnon 4.4 "Empirical Approach").
• Field measurement should be provided throughout the
entire length of the tunnel in order to check its assurned
behaviour.
4.6. Special Design Features
Special considerations may he neeessarv if unusual ground
behaviour is expected or is caused by ground improvements.
Some special design features and considerations arediscussed
below.
4.6.1. Ground impl'Ovement
techniqu8s
Grouting and injections. Intensive groming or injenions
of the ground may improve the ground characteristics
considered in the design model. Although in most cases
grouting is applied only for dosing discominuities in rock or
for strengthening soft ground. in both cases the goal is lO
achieve better homogeneüy.
Drainage anti. compressed air. UsuaHy the ground is
stabiiized bv dewatering it and by avoiding inf/ows Ol water.
Ground failure may be avoided if the pore water pressure is
minimized. The assumed ground characteristics mav be valid
only if successful drainage is possible or if water inflow is
prevented. as in tunnelling under compressed air.
244
TI':'<NELLlNG
AND UNDERGROUND
SPACE TECHNOLOGY
Ground [reezing, lrnproving the ground bv Ireezing
chang-es the ground properties. The time-dependent stress'train behaviour of Irozen ground can be significant. Freezing
draws water toward the Iining, causing an increase in water
volume and heave at the surface. Conerering on frezen ground
delavs the strength development of the concrete.
4.6.2. Unusual ground bahaviour
Suielling ground. Stress release due to tunnelling and-er
ground water intlux may cause swelling and a corresponding
increase in pressure on the lining. In these cases. a circular
cross-sectien or at least an invert arch is recommended. The
swelling resulting from a chemica! reaction, as in anhvdrid.
generally is much more pronounoed than that due to rhe
phvsical absorption of water. as in day.
Underground erosion. mtning subsidence, and sinhhoies.
Tunnelling in ground that is subject to settlements. as in the
case of gypsum erosion or mining subsidence, requires special
design considerations. A flexible lining that follows the
ground movements by utilizing its plastic deformation
capacity is more suitable in these cases than is a too-rigid or
briule, failure-prone lining, If the ground has sinkhole
potentials, a tunnel structure that can be repaired easilv mav
he more economical than a structure designed to allow the
bridging of the sinkholes,
5. In-Situ Monitoring
5.1. Pur pose of
In-Situ Measurements
In-situ monitoring during the excavation and at longer
intervals after the tunnel is cornpleted should be regarded as
an integral part of the design not only for checking the
structural safety and the applied design model but also for
verifying the basic conception of the response of the ground to
tunneiling and the effectiveness of the structural support.
The main objectives of in-situ monitoring are:
(I) To control the deformations of the tunnel. including
securing the open tunnel profile. The tirne-history
development of displacernents and convergences mav be
considered one safety criterion. although field measurements
do not vield the margins the structure can endure before
failing.
(2) To verify that the appropriate tunnelling method was
selected,
(3) To control the seulements at the surface. e.g, in order to
obtain information on the deforrnation pattem in the ground
and on that part of settlements caused by lowering the water
level.
(4) To measure the development of stresses in the structural
rnembers, indicating sufficient strength or the possibility of
strength Iailure.
(5) To indicate progressive
deformations,
which
require
immediate action for ground and support strengthening,
To furnish evidence for insurance claims, e.g. by
provicling resulls of levelling the settlements at the surface in
town areas.
5.2. Monitoring Methods
A programme for monitoring the deformations and stresses
during the excavation may comprise the followingmeasuremems (see Fig. 8):
(I) Levelling the crown (at the least) inside the tunnel as
soon as possible. With regard to imerpretation of the data.
2 reveals that often onlv a smal! fraction of the emire
crown movemem can be m~nitored because a larger part
occurs before the bolt ean be set. For difficult tunneHing, the
clistance between two crown readings may be as close as wIS m. LeveHing of thè invert is recommended for rock having
sweHing potemials.
(2) Convergence readings (in triangular settings; K in Fig.
Volume 3. Number 3, 1988
upper
outer
saencn
lining
[Dis t . "'SO ... l00ml
L
L
Illt:Th.lll
9,Om'______
readings cease to increase, However, a safety margin
against failure-e-especiallv sudden collapse-e-cannot be
deduced Irom measurernenr, except bv extrapolation.
L
...--14.0m ..•..
leveHing
convergences
l
K
grCK.Ind preSlll.G elCtensometer e
ringtorces
R sliding micrometer SL
8. Example of in-sim monitoring of the tunnel
lining, and the surface
exceoation, the preiiminarv
settlements.
8) should be rhe standard method for earlv information.
are easilv applied and are accurate ro within 1 rnm.
In a Iew cross-secuons, the linings mav he equipped
with stress cells for reading the ground pressures and ring
Iorces in the lining (G and R in Fig. 8).
(4) Stress cells also should he installed in a tew sections of
the final secoud lining if long-term readings are desired alter
the tunnel has been compieeed.
(5) Surface levelling along the tunnel axis and
perpendicular to ir vield settlements and the correlation to
measurements inside me tunnel (see Fig. 2).
(6) Extensometers. inclinometers, gliding micrometers rnav
he installed from the surface wel! ahead of the tunnelling face.•
vielding deformarion measurements within me ground (see
Fig. 8). Monitoring of the ground deformations is especially
appropriate for checking and interpreting the design model,
Therefore, [he installation should he combined with
convergence readings and stress cells in the same
6. Guidelines for me Structural
Detaiiing of the üning
On design aspects with regard to maintenance the reader is
relerred to other recommendations of the ITA (see T&UST
2:3). For concrete linings, [he following structural
specifications are suggested,
I) The thickness of a secend Iining of cast-in-place
concrete rnay have a lower limit of 25-30 cm to avoid concrete
placing problerns such as undercompaction
or honevcombing of concrete. The following lower limits mav he
recornmended:
-20 cm, if lining is unreinforced:
-25 cm, if lining is reinforeed.
-30 cm for watertight concrete.
(2) Reinforcemem mav be desirabie for crack control. even
when it is not required Ior covering inner stresses. On the
other hand, reinforcemem mav cause concrete-placing
problerns or long-term durabiliry problerns due to steel
corrosion. If reinforcement in the secend lining is provided
for crack control. a closely-spaced steel rnesh reinforcement
rnav have the following cross-secrions in both directions:
• At the outer surface. at least 1.5 cm-/m of steel;
• At the inner surface. at least 3.0 cm-/m of steel.
(3) The recommended minimum cover of reinforcement is:
cross-sectien.
3.0 cm
The frequencv of [he readings depends on how Iar frorn the
tunnelling face the measurements are taken, and on the
results. For exarnple, readings may he performed initiallv two
times a dav: then be reduced to one reading per week Iour
diameters behind theface: and end with one reading per
month if the time-data curves justifv this reduction in
measuremem readings.
5.3. Interpreting Resutts
of In-Situ Monitoring
The results of in-situ monitoring should be interprered
with regard to the excavation steps, the structural support
work, and the structural design model in conjunction with
safety considerations.
The actual readings normallv show a broad scatter of
values, Expectations of reliabrlity may not be met. especiallv
for pressure cells, beeause stresses and strains are verv local
characteristics. Detormauon and con vergen ce readings are
more reliablv obtainable because displacements register
integtals along a larger sectien of the ground,
The in-situ measurements should be interprered in
consideration of the Iollowing:
lID
The results should verify whether the tunnelling method
is appropriate.
Grapbed time-historv charts may reveal a decreasing rate
of deformauon. or unoover danger of coltapse.
• Large discrepancies between rhe theoretically prediered
and actuallv observed deformauons may force revision of
model. However, measurements are valid onlv
Ior the acmal state at ehe time and the place where thev
are taken. Long-term influences such as rising water
level. traffk vibrations, and long-term neep are not
re~rislere~during excavation.
•
readings mav promote visual understanding of the
strucmral behavior of groun<.!and support imeraction.
•• The readings may cover ooly a fraction Ol the acmal
phenomena if bolts and stress cells are installed too late
lID
(see Fig. 2).
lID
The tunnel may he considered
Volume 3, :\lumber 3. 1988
stabie when all the
5.0 cm-6.0 cm
4.0 cm-5.0 cm
5.0 cm
At the outer surface if a waterproof
membrane is provided,
At the outer surface if it is directly in
contact with the ground and ground
water.
At the inner tunnel surface.
For the tunnel invert andwhere water is
aggressive,
(4) For lining segments, specificauons (I), (2) and (3) above
are nor valid, especially if the segrnented tunnel ring is the
outer preliminary Iining. For detailing the tunnel segments,
special attention should be given to avoiding damage during
transport and erection,
(5) Sealing against water (waterproofing sheets) may be
necessarv under the following conditions:
• When aggressive water action threatens to damage
concrete and steel.
lID When the water pressure level is more than 15 m above
the Clown.
When there is a possibilirv of freezing of ingressing water
along the tunnel secnon close to the portals.
• Wnen the inner installations of the tunnel must be
lID
proteered.
(6) In achieving watertighmess of concrete. special
specifications of the concrete mixture, avoidanee of shrinkage
stresses and temperarare gradients during setting, and the
Iinal quality of the concrete are much more important than
theoretica I cornputarions of crack widths .
Temperature effects (tension stresses) may be somewhat
controlled by working joints (as close as 5 mat the portals)
and by additional surface reinforcemem in concrete exposed
to low temperatures,
(8) An initial lining of shotcrete may he considered to
participate in provi.ding stabi.Iitv of the tunnel only when the
long-term durability
of the shotcrete is preservecÎ.
Requiremems for achieving long-termdurability indude the
absence of aggressi.ve water. the limitalion of concrete
additives for acce!erating the seuing (Iiquid accelerators), and
avoiding shotcrete shadows behind steel arches and
reinforcements.
TlTNNELLING
AND UNDERGROt'ND
'sPACE TECHNOLOGY
245
I
eonsolîclGtion
I
'_
I
10
11,,,
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i
cf
the tunnel
rI
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zcne
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I nismmollY
I
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j roek
tl!fl'lll4ll"ature
!
I stre_
witllin
I Ihe wall
adaPlÎOll of roek
I round
I
aboul lhe lunneI .
Figure 9. Table of measured data end encountered conditions along a tunnel in Eranee.
HttigM Uo.,.
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legend:
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Figure 10. Predieeed ground conditions, tunnelling classes and design characteristics along a tunnel of the rapid railuiav line in
GeTmany.
246
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SPACE TECHNOLOGY
Volume 3; Number 3, 1988
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Figure 11. Predicted ground conditions along a tunnel line iexemple submiued by [apen).
Figure 12. Documentation of geology, ground classes. support, geotech nicaliield measurements gathered duringa tunnel project
in Austria.
Volume 3. Nurnber 3. 1988
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SPACE TECHNOLOGY
247
7. Exampies of Presentation
of Tunnel Design Data
Figures 9-12 are national exarnples of tabuiated
intermation
on geotechnical
condinons and design
characteristics given in condensed farm along a longitudinal
tunnel sectien. This inforrnation mav be part of the rendering
documents and should be amended with ongoing tunnelling,
By gatbering the data actuallv encountered along the tunnel
line in a sirnilar table, a comnarison can he made between
prediered and actual tunnelling conditions,
0
Nota
Referencas
Erdrnann. J. !983•.Comparison
of rhree-dirnensional
Braunschweig, West Cermanv: Berichte Instuut fur Statik.
Technica! Universitv of Braunschweig.
Gesta, P. 1986. Recommendations Ior use of the ronveraenceconfinemem rnethod. Tunnels Ouurages SouterrainS 73: 18-39.
International
Society of Rock Mechanica Commission
on
Classiticauon of Rocks and Rock Masses, 1981. Int. j. Rock
stechanics Mining Sci. 18: 85-110.
International Society of Rock Mechanics, 1975. ISRM Recornrnendauons on site invesrigation techniques,
International Tunnelling Association Worki.ng Croup on Structural
Design of Tunnels. 1982. Advances Tunnell. Technol. Subsurface
Use 2(3): 153-228.
of rwo-dimensional and development
desig-n rnethods Ior tunnels un Oermam.
'See, tor exarnple, the Swiss SlA Dokument 260 or the corresponding
C.S.-ASCE Code.
, on Structural
Appendix. International and Natienel Recommendations
Design of Tunnels.
Although the Iollowing selected list of recommendations by national and intemational organizations is not complete, it
neeertheless should provide the reader with sourees of additional inforrnation regarding the design of tunnels.
OrganizationiCountry
Pubheation
International Tunnelling
Views on structural design models for tunnelling. Adoances in Tunnelling
Association (ITA),
Technology and Subsurface Use 2:3 (1982).
International Society for
Rock Meeharnes (ISRM)
ISRM recommendations
on site investigation techniques, July 1975.
ISRM Committee on Field Tests:
Document No. l-Suggested Metbod for Determining Shear Strength
Document No. 2-Suggested
Methods Ior Rock Bolt Tesung
ISRM Commiuee on Laboratory Tests; ISRM ComJnittee on Suielling Rocks:
Document No, I-Suggesteà
Methods for Determining
the Uniaxial
Compressive Strength of Rock Matenals and Point Load Strength Index.
Document No. 2-Suggested
Porosity, Density, Absorption
Durability Index Properties.
Methods for Determining Water Content.
and Related Properties. Swelling and Slake
Australian Standard 1726 - S.A.A. Site Investigation Code,
Austral ia
Australian Standard 1289 - Methods of Testing Soils for Engineering Purposes.
Austria
ÖNORM E 2203 Untertagebaunorm,
Werkvertragsnorm.
Richtlinien und Vertragsbeseimmungen,
Projektierungsrichtlinien
für Oeotechnische
Forschungsges, Srassenwesen, Nov. 1977.
Federal Republic of Germany
(in Cermarn
Arbeiten, RVS 9.240 u. 9.241,
Reeommendations Ior rhe design of underground openings in rock. TunnelbauTeschenbucn 1980, Gluckaui-Verlag, Essen (1980), pp. 157-239.
Recornmendations for the analvsis of Tunnels in soft ground (980), Bautechnik
10 (980), Berlin, pp, 349-356.
Recommendations Ior the Concrete Lining of Tunnels in soft ground (986).
Bautechnik 10 (986), Berlin, pp, 331-338.
Tunnels et Ouoreges Souterrains, Special Issue July 1982, pp, 32-123;
France
Rêflexions sur les methodes usuelles de calcul du revêtement des souterrains
(Usual calculation methods Ior the design of tunnel linings).
248
TVNNELUNG
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Volume 3. Nurnber 3, 1988
Prèsentation de la mèthode de construction des tunnel avec sourènernent
immediat par bèton projetè et boulonnage (Presentation of the tunnel
construction method with imrnediate support by shotcrete and bolting).
Recomrnandarions SUf les condinons d'emploi du boulonnage (Recommendations for condinons of the use of bolting).
Tunnels et Ouurages Souterrains 73 (jan.zFeb. 1986), pp.
Recommendations Ior use of the convergence-confinemem method,
18-38:
Tunnels et Ouurages Souterrains 67 (jan.z Feb. 1985), pp. 32-43:
Recommandations relatives au choix d'un type de soutenement en galerie
(Recornmendations Ior the selection of tunnel support).
Tunnels et Ouutages (1984), pp, 80-97: Recommandations relativa à l'ernploi
des citres dans ia construction des ouvrages souterrains (Recommendations on
the use of steel arches as temporatv support in tunnel structures).
Japan
Tunnel Engineering Committee,
Japan Society of Civil Engineering,
Japan Tunnelling Association
Standard Specificatiens for Tunnels:
Mountain Tunnelling
Shield Tunnelling
Metbod. Nov. 1986.
Method.
J une
1986.
Cut-aud-eover Method. june 1986.
Switzerland
Recommandation SlA No. 199: Etude du massif rocheux pour les travaux
souterrains. 1975. (Also in German)
Norme SlA No. 198:Travaux souterrains (avancement à l'explosif), 1975. (Also
in German)
Recommandation SlA No. 198/1: Construction de tunnels et de galeries en
roeher-au moven de tunneliers, 1985. (Also in German)
U nited Kingdom
British Standard 1377. Methods of test for soils Ior civil engineering purposes.
British Standards Insritution, 1975.
British Standard 5930, Code of Praenee Ior site invesugations,
Institution, 1981.
British Standards
Craig, R. N. and Muir Wood, A. M. A review of tunnel lining praenee inthe
Unired Kingdorn. TRRL Supplementary Report 335, 1978.
Tunnelling
Waterproofing. CIRIA Report 81,1979.
Dumbleton, M. J. and West, G. A guide to site investigation
tunnels. TRRL Laberatory Report 740,1976.
Unieed States of Amenca
American Society of
Civil Engineers (ASCE)
Volume 3, Number 3, 1988
procedures for
Guidelines fOT Tunnel Lining Design. Ed. by T. O'Rourke. ASCE Technica]
Committee on Tunnel Lining Design, Teehuical Council on Research.
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