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AITES
ITA
Towards animproved use
of undergroundSpace
In Consultative Status, Category II with theUnited Nations Economic and Social Council
http://www.ita-aites.org
ASSOCIATIONINTERNATIONALE DES TRAVAUX
EN SOUTERRAININTERNATIONALTUNNELLINGASSOCIATION
Recommendations and Guidelines for Tunnel Boring Machines (TBMs)
MECHANIZED TUNNELLING
Title
Topic
published
Abstract: -
Résumé: -
Remarks: This report contains four individual reports prepared by ITA Working Group No. 14 ("Mechanized
Tunnelling"). The purpose of the reports is to provide comprehensive guidelines and recommendations for
evaluating and selecting Tunnel Boring Machines (TBMs) for both soft ground and hard rock. The reports are
contributed by representatives from seven countries as follows:
I. "Guide lines for Selecting TBMs for Soft Ground", Japan and Norway
II. "Recommendations of Selecting and Evaluating Tunnel Boring Machines", Germany, Switzerland and
Austria
III. "Guidelines for the Selection of TBMs", Italy
IV. "New Recommendations on Choosing Mechanized Tunnelling Techniques", France
Each report offers up to date technologies of mechanized tunneling for both hard and soft ground and includes,
among others, classifications of TBMs, their application criteria, construction methods, ground supporting
system and other equipment necessary for driving tunnels by TBMs.
Since a cylindrical steel shield was first used for the construction of the Themes River Tunnel Crossing in
England in 1823, tunnel works have been steadily mechanized. Especially, as urban tunneling was developed in
the latter half of the 20th century, technological progress seen in this area was remarkable. Meanwhile, the
circumstances surrounding tunnel construction have become increasingly complex and difficult. Tunneling
technologies in recent years are developed by sophisticated and multi-disciplinary engineering principles to
cope with the diverse physical, environmental and social circumstances. This report is intended to provide
fundamental and useful knowledge of mechanical tunneling that can be used by designers, manufacturers and
the end users of tunnel boring machines.
It is hoped that this report provides common ground for understanding tunneling technologies among
international tunneling communities and eventually helps establish a standard set of criteria for designing and
utilizing tunnel boring machines.
in "Recommendations and Guidelines for Tunnel Boring Machines (TBMs)",
Working Group: WG 14 - "Mechanized Tunnelling"
AuthorITA WG Mechanized Tunnelling
Open Session, Seminar, Workshop: -
Others: Recommendations
by ITA - AITES, www.ita-aites.org
pp. 1 - 118, Year 2000
Secretariat : ITA-AITES c/o EPFL - Bât. GC – CH-1015 Lausanne - SwitzerlandFax : +41 21 693 41 53 - Tel. : +41 21 693 23 10 - e-mail : [email protected] - www.ita-aites.org
RECOMMENDATIONS AND GUIDELINESFOR TUNNEL BORING MACHINES (TBMs)
TRIBUNE HORS SÉRIEMAI 2001 - ISSN 1267-8422
WORKING GROUP N°14 - MECHANIZED TUNNELLING - INTERNATIONAL TUNNELLING ASSOCIATION
ASSOCIATIONINTERNATIONALE DES TRAVAUX
EN SOUTERRAIN
AITESITAINTERNATIONALTUNNELLINGASSOCIATION
International Tunnelling Association25, Avenue François Mitterrand – Case nº1
69674 BRON CedexFranceTEL: 33(0) 4 78 26 04 55FAX: 33(0) 4 72 37 24 06e-mail: [email protected]://www.ita-aites.org
© International Tunnelling Association. All rights reserved. No part of this publication may bedistributed and/or reproduced, stored in a retrieval system or transmitted in any form or by anymeans, electronic, mechanical, photocopying, recording or otherwise , without the prior writtenpermission of publisher, International Tunneling Association
Preface
This report contains four individual reports prepared by ITA Working Group No. 14 (“MechanizedTunneling”). The purpose of the reports is to provide comprehensive guidelines andrecommendations for evaluating and selecting Tunnel Boring Machines (TBMs) for both soft groundand hard rock. The reports are contributed by representatives from seven countries as follows:
I. “Guide lines for Selecting TBMs for Soft Ground”, Japan and NorwayII. “Recommendations of Selecting and Evaluating Tunnel Boring Machines”, Germany,
Switzerland and AustriaIII. “Guidelines for the Selection of TBMs”, ItalyIV. “New Recommendations on Choosing Mechanized Tunnelling Techniques”, France
Each report offers up to date technologies of mechanized tunneling for both hard and soft groundand includes, among others, classifications of TBMs, their application criteria, construction methods,ground supporting system and other equipment necessary for driving tunnels by TBMs.
Since a cylindrical steel shield was first used for the construction of the Themes River TunnelCrossing in England in 1823, tunnel works have been steadily mechanized. Especially, as urbantunneling was developed in the latter half of the 20th century, technological progress seen in this areawas remarkable. Meanwhile, the circumstances surrounding tunnel construction have becomeincreasingly complex and difficult. Tunneling technologies in recent years are developed bysophisticated and multi-disciplinary engineering principles to cope with the diverse physical,environmental and social circumstances. This report is intended to provide fundamental and usefulknowledge of mechanical tunneling that can be used by designers, manufacturers and the end usersof tunnel boring machines.
It is hoped that this report provides common ground for understanding tunneling technologies amonginternational tunneling communities and eventually helps establish a standard set of criteria fordesigning and utilizing tunnel boring machines.
Shoji KuwaharaTutor, Working Group No. 14International Tunnell ing Association
GENERAL CONTENTS
I. GUIDELINES FOR SELECTING TBMS FOR SOFT GROUNDby Japan and Norway
1 Classification of tunnel excavation machine2 Investigation of existing conditions and applicability of TBM3 Tunnel boring machine (TBM)4 Tunnels constructed by TBM in JapanAPPENDIX: TBM Performance in hard rock
II. RECOMMENDATIONS OF SELECTING AND EVALUATINGTUNNEL BORING MACHINES
by Germany, Switzerland and Austria
1. Purpose of the recommendations2. Geotechnics3. Construction methods for mined tunnels4. Tunneling machines TM5. Relationship between geotechnics and tunneling machines
III. GUIDELINES FOR THE SELECTION OF TBMSby Italy
1. Classification and outlines of tunnel excavation machines2. Conditions for tunnel construction and selection of TBM tunneling method3. References
IV. NEW RECOMMENDATIONS ON CHOOSING MECHANIZEDTUNNELLING TECHNIQUES
by France
1. Purpose of these recommendations2. Mechanized tunnelling techniques3. Classification of mechanized tunneling Techniques4. Definition of the different mechanized tunnelling techniques classified in chapter 35. Evaluation of parameters for choice of mechanized tunneling techniques6. Specific features of the different tunneling techniques7. Application of mechanized tunneling techniques8. Techniques accompanying mechanized tunneling9. Health & Safety
Japan and Norway
Guidelines for Selecting TBMsfor Soft Ground
ITA Working Group No. 14Mechanized Tunneling
I-ii
PREFACE
Tunnels are playing an important role in the development of urban infrastructures. Severalconstruction methods for tunneling have been developed to cope with various geological conditions.Those methods can be categorized in two types; drill and blast method and by the use of TunnelBoring Machine (TBM). This report focuses on tunneling by TBM and is prepared to offerguidelines and recommendations for selecting types of TBMs for urban tunnel construction. Itsmain purpose is to help project owners, contractors and manufacturers evaluate the applicability andcapability of TBMs and other factors that should be taken into consideration for selecting of TBMs.
ITA has been collecting data and information from its member countries, in hope of providing acomprehensive international “manual” for TBM tunneling methods. As the contents of this reportrepresent Japanese and Norwegian versions of the subject, they may be revised or supplemented asnecessary to meet particular conditions of the respective countries.
This report consists of two parts; one is for the TBMs in soft ground prepared by Japanese WorkingGroup and the other is for the TBMs in hard rock prepared by Norwegian Working Group. TheNorwegian version is an excerpt from the “Project Report 1-94, Hard Rock Tunnel Boring”published by University of Trondheim, Norway, and is included in Appendix. Small diametertunneling is not included in this report (e.g. micro-tunneling with pipe jacking etc.).
Technologies surrounding TBMs have been receiving great deal of attention. They have beenprimarily aimed at mechanization and automation of tunnel boring under various geologicalconditions, with the combined technologies of soil, mechanic and electronic engineering. Thetechnological progress will continue to come from innovative commitments of tunnel builders,teaming with tunnel designers and manufacturers.
It is hoped that this report will assist the members of ITA publish the comprehensive internationalmanual for TBMs and will further contribute to the development of tunneling technologies.
I-iii
CONTENTS
1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINE...............................................................................11.1 Mechanical Excavation Type (Fig. 1.3) ...................................................................................................................31.2 Earth Pressure Balance (E.P.B.) Type (Fig. 1.4).....................................................................................................31.3 Slurry Type (Fig. 1.5) .................................................................................................................................................4
2 INVESTIGATIONS OF EXISTING CONDITIONS AND APPLICABILITY OF TBM....................................52.1 Site Investigations........................................................................................................................................................5
2.1.1. Existing site conditions ....................................................................................................................................52.1.2. Existing structures and utilities .......................................................................................................................52.1.3. Topography and geology..................................................................................................................................52.1.4. Environmental impact.......................................................................................................................................5
2.2 Applicability of TBMs ...............................................................................................................................................53 TUNNEL BORING MACHINE (TBM) ......................................................................................................................8
3.1 Machine Specifications ..............................................................................................................................................83.1.1. Essential parts of TBM.....................................................................................................................................83.1.2. Structure of TBM..............................................................................................................................................83.1.3. Types of TBMs for soft ground.......................................................................................................................93.1.4. Selection of TBM..............................................................................................................................................9
3.2 Orientation and operation of machine................................................................................................................... 123.2.1. Excavation Control System .......................................................................................................................... 123.2.2. Direction Control and Measurement System ............................................................................................. 12
3.3 Cutter Consumption................................................................................................................................................. 123.3.1. Bit types and Arrangement ........................................................................................................................... 123.3.2. Wear of Bit...................................................................................................................................................... 123.3.3. Long Distance Excavation ............................................................................................................................ 12
3.4 Ground Support and Lining.................................................................................................................................... 133.4.1. Design of Lining............................................................................................................................................. 133.4.2. Types of Segment........................................................................................................................................... 133.4.3. Fabrication of Segment.................................................................................................................................. 143.4.4. Erection of Segments..................................................................................................................................... 15
3.5 Auxiliary Facilities................................................................................................................................................... 163.5.1. Earth pressure balance type machine .......................................................................................................... 163.5.2. Slurry type tunneling machine ..................................................................................................................... 17
4 TUNNELS CONSTRUCTED BY TBM IN JAPAN ............................................................................................... 174.1 Soft ground tunneling in Japan .............................................................................................................................. 174.2 Types of TBMs and ground conditions................................................................................................................. 18
4.2.1. Soil Conditions and Types of TBMs ........................................................................................................... 184.2.2. Groundwater pressure and Type of TBMs.................................................................................................. 19 Max. Size of Gravel and TBM Type ......................................................................................................................... 20
4.3 Size of TBM.............................................................................................................................................................. 21Weight............................................................................................................................................................................. 21Length/Diameter (L/D) ................................................................................................................................................ 21
APPENDIX: TBM PERFORMANCE IN HARD ROCK .............................................................................................. 22A-1 General......................................................................................................................................................................... 22A-2 Advance ....................................................................................................................................................................... 22
A-2.1 Rock Mass Properties........................................................................................................................................ 22A-2.2 Machine Parameters........................................................................................................................................... 24A-2.3 Other Definitions................................................................................................................................................ 26A-2.4 Gross advance rate............................................................................................................................................. 28A-2.5 Additional Time Consumption ......................................................................................................................... 29
A-3 Cutter Consumption ................................................................................................................................................... 30A-4 Troubles and Countermeasures................................................................................................................................. 32
A-4.1 Causes for Trouble............................................................................................................................................. 32A-4.2 Countermeasures ................................................................................................................................................ 33
I-iv
FIGURES
FIG. 1.1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINES ........................................................................1FIG. 1.2 TUNNEL EXCAVATION MACHINES .........................................................................................................2FIG. 1.3 MECHANICAL EXCAVATION TYPE TUNNELING MACHINE....................................................................3FIG. 1.4 EARTH PRESSURE BALANCE TYPE TUNNELING MACHINE...................................................................4FIG. 1.5 SLURRY TYPE TUNNELING MACHINE ...................................................................................................4FIG. 3.1 COMPONENTS OF TUNNELING MACHINE ..............................................................................................8FIG. 3.2 TYPE OF TBM FOR SOFT GROUND.......................................................................................................9FIG. 3.3 FLOW CHART FOR SELECTING TBM FOR SOFT GROUND..................................................................10FIG. 4.1 TUNNELS DRIVEN BY TBMS IN JAPAN ...............................................................................................17FIG. 4.2 SOIL CONDITIONS AND TYPE OF TBMS .............................................................................................18FIG. 4.3 GROUNDWATER PRESSURE AND TYPE OF TBMS ...............................................................................19FIG. 4.4 GRAVEL SIZE AND TYPE OF TBMS ....................................................................................................20FIG. 4.5 DIAMETER AND WEIGHT OF TBM (EPB, SLURRY)............................................................................21FIG. 4.6 DIAMETER AND LENGTH/DIAMETER (L/D) OF TBM ..........................................................................21FIG. A.1 RECORDED DRILLING RATE INDEX FOR VARIOUS ROCK TYPES ........................................................22FIG.A.2 RECORDED CUTTER LIFE INDEX FOR VARIOUS ROCK TYPES .............................................................23FIG. A.3 FRACTURE CLASSES WITH CORRESPONDING DISTANCE BETWEEN PLANES OF WEAKNESS ..............23FIG. A.4 RECORDED DEGREE OF FRACTURING FOR VARIOUS ROCK TYPES .....................................................24FIG. A.5 FRACTURING FACTOR, CORRECTION FACTOR FOR DRI≠49..............................................................24FIG. A.6 RECOMMENDED MAX. GROSS AVERAGE PER DISC.............................................................................25FIG. A.7 CUTTERHEAD R.P.M. AS FUNCTION OF TBM-DIAMETER...................................................................25FIG. A.8 BASIC PENETRATION FOR CUTTER DIAMETER = 48.3 MM AND CUTTER SPACING = 70 MM..............26FIG. A.9 CORRECTION FACTOR FOR CUTTER DIAMETER≠483 MM ..................................................................27FIG. A.10 CORRECTION FACTOR FOR AVERAGE CUTTER SPACING≠70 MM......................................................27FIG. A.11 CUTTING CONSTANT CC AS A FUNCTION OF CUTTER DIAMETER ....................................................28FIG. A.12 MAINTENANCE AS FUNCTION OF NET PENETRATION RATE..............................................................29FIG. A.13 BASIC CUTTER RING LIFE AS FUNCTION OF CLI AND CUTTER DIAMETER.......................................31FIG. A.14 CORRECTION FACTOR FOR CUTTING RING LIFE.............................................................................31FIG. A.15 CORRECTION FACTOR FOR CUTTING RING VS. QUARTZ CONTENT.................................................32
I-v
TABLES
TABLE 2.1 COMPARISON OF EXCAVATION METHODS.............................................................................................................6TABLE 2.2 APPLICABILITY OF TBMS TO SOFT GROUND CONDITIONS...............................................................................7TABLE 3.1 RELATIONSHIP BETWEEN CLOSED TYPE TUNNELING MACHINE AND SOIL CONDITIONS.......................... 11TABLE 3.2 LOADS ON SEGMENTS ......................................................................................................................................... 13TABLE 3.3 ALLOWABLE STRESSES OF CONCRETE FOR PRE-FABRICATED CONCRETE SEGMENTS ................................. 14TABLE 3.4 TYPICAL DIMENSIONS OF SEGMENTS (MM)..................................................................................................... 15TABLE 3.5 AUXILIARY FACILITIES........................................................................................................................................ 16TABLE 4.1 TBMS IN SOFT GROUND PERFORMED IN JAPAN ............................................................................................... 17
I-1
1 CLASSIFICATION OF TUNNELEXCAVATION MACHINE
Tunnels are constructed under many types ofgeological conditions varying from hard rockto very soft sedimentary layers. Procedurescommonly taken for tunneling are excavation,ground support, mucking and lining. Varietyof construction methods have been developedfor tunneling such as cut and cover, drill andblast, submerged tube, push or pulling box, andby the use of tunnel boring machine (TBM).
TBM was first put into practical use for miningof hard rock, where the face of the tunnel isbasically self-standing. For tunneling throughearth, open type machine was used, in which ametal shield was primarily used for protectivedevice for excavation works.
For tunneling through sedimentary soil,tunnel face is stabilized by breasting,pneumatic pressure or other supporting means.Closed type- tunneling machine wasdeveloped, which utilizes compressed air tostabilize tunnel face. The closed type-machinestarted to dominate for soft ground tunneling,especially in the countries where many tunnelsare driven through sedimentary soil layers.
Tunnel excavation machines can be classifiedby the methods for excavation (full face orpartial face), the types of cutter head (rotationor non-rotation), and by the methods ofsecuring reaction force (from gripper orsegment). Several types of tunnel excavationmachines are illustrated in Fig. 1.1 and Fig.1.2,
Fig. 1.1 Classification of Tunnel Excavation Machines
I-3
1.1 Mechanical Excavation Type (Fig. 1.3)
The mechanical excavation type-tunnelingmachine is equipped with a rotary cutter headfor continuous excavation of tunnel face.There are two types of cutter heads; one is thedisk type and the other is the spoke type (rodstyle radiating from the center). The disk typeis suitable for large cross section tunnelswhere tunnel face is stabilized by the diskcutter head. This type of machine is capableof excavating soils containing gravel andboulders with the openings in the disk, whichare adjustable according to the size of graveland boulders. The spoke type is frequentlyused for small cross section tunnels where thetunneling face is relatively stable. Gravel andboulders are removed by the rotating spokecutter.The mechanical excavation type-tunnelingmachine is suitable for the diluvial depositthat has a self-standing face. Application ofthis type of machine to the alluvial deposits,which usually do not form a self-standingface, requires one or more supplementarymethods such as pneumatic pressure,additional de-watering, and chemicalgrouting.
Hopper
Cutter driving mo
Belt conveyo
Cutter head
Fig. 1.3 Mechanical Excavation TypeTunneling Machine
1.2 Earth Pressure Balance (E.P.B.) Type(Fig. 1.4)
Earth pressure balance type tunnelingmachine converts excavated soil into high-
density slurry mix. The face of the tunnel issupported by the pressurized slurry mixinjected into a space between its cutter headand a watertight steel bulkhead. It consists ofthe following four components:
i) A cutter head for excavating thegroundii) A slurry mixer for mixing theexcavated muck with high-density slurryiii) Soil-discharging devise for removalof the muckiv) Pressure controlling devise forkeeping the pressure of slurry-soil mixsteady
The earth pressure balance type is classifiedinto two types by the additives injected toconvert the excavated muck into high-densityslurry. One is earth pressure type and theother is high-density slurry type.
(1) Earth pressure typeEarth pressure type machine cut the groundwith a rotary cutter head. Clay-water slurryis injected into the cutter chamber and ismixed with excavated muck. The slurry mixis pressurized to stabilize the tunnel face andcreate the driving force of the machine. Theexcavated muck is later separated from theslurry and discharged by a screw conveyor.This type is suitable for clayey soil layers.
(2) High-density slurry typeHigh-density slurry type machine cut theground with a rotary cutter head. Theexcavated muck is mixed with clay-waterslurry. by the rotating cutter. Highly plasticand dense additive is added to the slurry mixin the cutter chamber. The additives areused to increase the fluidity and to reducethe permeability of the soil. The high-density slurry mix stabilizes the tunnel face.The excavated muck is discharged by ascrew conveyor. This type is suitable forsand or gravel layers.
I-4
Cutter headCutter driving motor
Mixing wingCutter chamber
Screw conveyor
Additives
Fig. 1.4 Earth Pressure Balance TypeTunneling Machine
1.3 Slurry Type (Fig.1.5)
Slurry type tunneling machine cut the groundwith a rotary cutter head. The cutter chamberis filled with pressurized slurry mix tostabilize the face of the tunnel. The slurrymix is circulated through pipes to transport itto a slurry treatment plant where theexcavated muck is separated from slurry mix.The excavated muck is discharged throughpipes and the slurry is circulated back to thecutter head for re-use. The slurry typemachine consists of the following threecomponents:
i ) A rotating cutter head forexcavating ground
ii) A slurry mixer for the production ofslurry mix with desired density andplasticity
iii) Slurry pumps to feed/discharge,circulate and to pressurize slurry mix
iv) Slurry treatment plant to separateexcavated muck from slurry
Cutter head Cutter driving motor
Bulkhead
Cutter chamber
Slurry feed pipe
Slurry discharge
Fig. 1.5 Slurry Type Tunneling Machine
I-5
2 INVESTIGATIONS OF EXISTINGCONDITIONS ANDAPPLICABILITY OF TBM
2.1 Site Investigations
Site investigations are conducted to obtainbasic data necessary for determining theproject scale, selection of a tunnel route andits alignment, applicability of TBMs, and itsenvironmental impact, and for planning,designing and construction of TBM tunnels.Results of the investigations are also used foroperation and maintenance of TBM. Themajor items of investigation are indicated inthe following subsections.
2.1.1. Existing site conditionsExisting site conditions along the proposedtunnel route are investigated to survey thefollowing site conditions
i) Land use and related property rightsii) Future land use planiii) Availability of land necessary for
constructioniv) Traffic and the type of the roadsv) Existing rivers, lakes and oceanvi) Availability of power, water and
sewage connectionsResults of the investigation are mainly usedfor determining the tunnel route, itsalignment, locations and areas of accesstunnels and temporary facilities.
2.1.2. Existing structures and utilitiesExisting structures and utility lines near thetunnel are investigated for their futurepreservation and for securing the safety ofTBM tunneling.
i) Existing surface and undergroundstructures
ii) Existing utilitiesiii) Wells in use and abandonediv) Remains of removed structures and
temporary structures
2.1.3. Topography and geologyTopographical and geological conditions arethe most important factors affecting the TBMdesign and construction. In particular, thefollowing items should be investigated byfield survey, boring, etc.
i) Topographyii) Geological structureiii) Ground conditionsiv) Groundwater
2.1.4. Environmental impactEnvironmental impact analysis of the tunnelconstruction should be carried out to selectand design construction methods thatminimize the environmental impacts to theexisting ecosystem.
i) Noise and vibrationii) Ground movementiii) Groundwateriv) Oxygen deficient air and hazardous
gas such as methane gasv) Chemical groutingvi) Discharge of excavated muck
2.2 Applicability of TBMs
Three types of excavation methods, drillingand blasting, TBM for hard rock, and TBMfor soft ground, are compared in terms oftunnel dimensions, geological conditions andenvironmental impacts, and are shown inTable 2.1. The shaded portions of this tableindicate the application of TBMs for softground.Among the soft ground TBMs, the mechanicalexcavation type, earth pressure balance typeand slurry type is compared in Table 2.2 interms of their applicability to various types ofsoft ground. This table also indicates theitems that should be taken into considerationwhen applying TBM to soft ground. .As indicated in Table 2.2, earth pressurebalance and slurry types are suitable foralluvial deposits that generally are not self-standing. Slurry type is effective for drivingthrough grounds with high groundwaterpressure, such as those under river or seabedbecause the stability of tunnel face can bemaintained by properly mixed and pressurizedslurry mix. On the other hand, earth pressurebalance type is not suitable for grounds withhigh groundwater pressure because it isdifficult to maintain the pressure balancedagainst ground water pressure due to theopening for the soil discharging screwconveyor.
I-6
Tabl
e2.1
Com
pari
son
ofE
xcav
atio
nM
etho
ds
TB
ME
xcav
atio
n M
etho
d
Con
ditio
nsD
rilli
ng a
nd B
last
ing
For
Har
d R
ock
For
Soft
Gro
und
tunn
el le
ngth
Equ
ipm
ent c
ost i
s re
lative
ly lo
w.
Exc
avat
ion
cost
is n
ot g
reat
lyin
flue
nced
by
the
tunn
el le
ngth
.
The
cos
t of
tunn
el b
orin
g m
achi
nes
isge
nera
lly h
igh.
It i
s su
itabl
e in
long
ertu
nnel
exca
vatio
ns.
The
cos
t of
tunn
el b
orin
g m
achi
nes
isge
nera
lly h
igh.
It i
s su
itabl
e in
long
ertu
nnel
exca
vatio
ns.
shap
e of
the
cros
sse
ctio
n
Bas
ical
ly, th
e sh
ape
of ex
cava
tion
has
an a
rche
d sh
ape
at th
e cr
own.
The
sha
pe o
f th
e se
ctio
n ca
n be
chan
ged
duri
ng th
e co
nstr
uctio
n.
Bas
ical
ly, th
esh
ape
of th
e ex
cava
tion
is a
cir
cle.
Aft
er b
orin
g, o
ther
sha
pes
are
poss
ible
usi
ng d
rilli
ng a
nd b
last
ing
asth
e re
sult
of e
nlarg
emen
t.
Bas
ical
ly, th
e sh
ape
of th
e exc
avat
ion
is a
cir
cle.
Sem
icir
cle,
mul
ti-ci
rcle
, oval
etc
. are
also
pos
sibl
e us
ing
spec
ial t
unne
ling
mac
hine
s fo
r ex
cava
tion.
Tun
nel
Feat
ures
size
of
the
cros
sse
ctio
n
Gen
eral
ly, it
is p
ossi
ble
up to
150
m2 .T
he la
rges
t rec
ord
is b
igge
r th
an20
0m2 .
The
larg
est r
ecor
d is
app
roxi
mat
ely
12m
for
the
max
imum
dia
met
er o
f th
etu
nnel
.
The
larg
est r
ecor
d is
app
roxi
mat
ely14
m f
or th
e m
axim
um d
iam
eter
of
the
tunn
el.
hard
roc
kSu
itabl
eSu
itabl
eex
cept
for
the
extr
a-ha
rd r
ock
(s>
200M
Pa)
Not
app
licab
le
sem
i-ha
rd r
ock
Suita
ble
Suita
ble
Not
app
licab
le
Wea
k la
yers
suc
has
fra
ctur
ed z
ones
and
aqui
fer
zone
s
Var
ious
cou
nter
mea
sure
s be
com
ene
cess
ary.
It is
not
sui
tabl
e in
are
a w
here
wea
kgr
ound
or
wat
er in
flow
will
be
freq
uent
ly e
ncou
nter
ed.
App
licab
leSe
eTa
ble.
2.2
Geo
logi
cal
Con
ditio
ns
Soil
Not
app
licab
leN
ot a
pplic
able
Mos
t sui
tabl
eSe
eTa
ble
2.2
Env
iron
men
tal
Con
ditio
nsN
oise
and
Vib
ratio
n
Due
to n
oise
and
vib
ratio
n, it
is n
otsu
itabl
e in
the
vici
nity
of
hous
es a
ndim
port
ant s
truc
ture
s.A
sup
plem
enta
ry m
etho
d is
nec
essa
ryto
red
uce
the
effec
ts o
f no
ise
and
vibr
atio
n.
Com
pare
d to
the
drill
ing
and
blas
ting
ther
e is
less
effe
ct o
f no
ise
and
vibr
atio
n to
the
hous
es a
nd im
port
ant
stru
ctur
es.
The
re is
less
effe
ct o
f no
ise
and
vibr
atio
n to
the
hous
es a
nd im
port
ant
stru
ctur
es th
an o
ther
exca
vatio
nm
etho
ds.
I-7
Tabl
e 2.2
App
licab
ility
of
TB
Ms
to
Sof
t Gro
und
Con
diti
ons
Ope
n ty
peC
lose
d t
ype
Ear
th
pres
sure
ba
lanc
e ty
peT
BM
type
Gro
und
cond
ition
N-v
alue
wat
er c
onte
ntor
perm
eabi
lity
Mec
hani
cal ex
cava
tion
type
Ear
th
pres
sure
ty
peH
igh -
dens
ity s
lurr
y ty
peSl
urry
type
Allu
vium
cla
y
0 –
530
0% –
50%
s-F
ace
stab
ility
-Gro
und
settl
emen
tl
-Diff
icul
ty
in ex
trem
ely
wea
k cl
ay-V
olum
e co
ntro
l of
disc
harge
d
soil
_-E
arth
pre
ssur
e is
mor
esu
itabl
e.s
-Diff
icul
ty
In ex
trem
ely
wea
k cl
ay-S
lurr
y s
pout
ing
onsu
rfac
e-I
ncre
ase o
f se
cond
ary
slur
ry t
reat
men
t p
lant
Dilu
vium
cla
y7
– 20
W <
50%
l-E
xist
ence
of
wat
erbe
arin
g s a
nd-B
lock
a ge
in slit
cha
mbe
rl
-Liq
uidi
ty o
f so
il-V
olum
e c
ontr
ol
ofdi
scha
rged
soi
l_
-Ear
th p
ress
ure
is m
ore
suita
ble.
l-I
ncre
ase
of s
econ
dary
slur
ry t
reat
men
t pl
ant
Soft
roc
k(m
udst
one)
> 5
0W
< 2
0%l
-Exi
sten
ce o
f w
ater
bear
ing
sand
-Wea
r of
cut
ter
bits
_
-Ear
th p
ress
ure
with
slur
ry i
s m
ore
suita
ble
whe
n t
here
is w
ater
bear
ing
san
d.
_-S
uita
ble w
hen
the
re is
wat
er b
eari
ng s
and
_-S
uita
ble w
hen
the
re is
wat
er b
eari
ng
san
d
Loo
se s
and
5 –
3010
-2 –
10-3
(cm
/s)
x-U
nsta
ble f
ace
s-
Con
tent
s of
fin
e
part
icle
sl
-Hig
hly-
advan
ced
exca
vatio
n co
ntro
ll
-Hig
hly-
advan
ced
exca
vatio
n c
ontr
ol-Q
ualit
y co
ntro
l of
slur
ry
solu
tion
Den
se s
and
> 3
010
-3 –
10--
4
(cm
/s)
s-F
ace
stab
ility
-Gro
undw
ater
lev
el,
perm
eabi
lity
s-
Con
tent
s of
fin
epa
rtic
les
l-W
ear
of
cutte
r bi
ts-D
osag
e of
add
itives
l-Q
ualit
y co
ntro
l o
fsl
urry
so
lutio
n
Sand
grav
el
> 3
010
0 – 1
0-2
(cm
/s)
s-F
ace
sta
bilit
y-G
roun
dwat
er l
evel
,pe
rmea
bilit
ys
- C
onte
nts
of f
ine
part
icle
sl
-Wea
r o
f c
utte
r bits
-Dos
age
of
add
itives
l
-Run
ning
aw
ay o
f sl
urry
-Grav
el
crus
her
-Flu
id tr
ansp
orta
tion
syst
emSa
nd a
nd g
ravel
With
bou
lder
s>
50
100 –
10-1
(cm
/s)
x
-Fac
e st
abili
ty-B
ould
er c
rush
er-W
ear
of
cutte
r b
its
and
face
s
- C
onte
nts
of fin
e pa
rtic
les
-Wea
r of
cutte
r bi
ts a
nd f
ac-B
ould
er c
rush
er-B
ould
er d
iam
eter
for
screw
-con
veye
r
l
-Wea
r of
cutte
r bi
ts-B
ould
er c
rush
er-B
ould
er dia
met
er fo
rsc
rew-c
onve
yer
s
-Run
ning
aw
ay o
f sl
urry
-Bou
lder
cru
sher
-Flu
id tr
ansp
orta
tion
syst
em
App
licab
ility
for
grou
ndC
ondi
tion
chan
ges
It is
impo
ssib
le to
cha
nge
exca
vatio
n s
yste
m.
App
licab
leA
dditiv
e
inje
ctio
n eq
uipm
ent
beco
mes
ne
cess
ary.
App
licab
leIn
gen
eral
, it i
s w
idel
yap
plic
able
for
var
ious
so
ilco
nditi
ons.
App
licab
leIn
gen
eral
, It i
s w
idel
yap
plic
able
for
var
ious
so
ilco
nditi
ons.
Not
e:l
App
licab
le,
s C
onsi
dera
tion re
quir
edx
Not
appl
icab
leIt
emst
o c
onsi
der w
hen a
pply
ing
In c
ase o
f x,
rea
sons
for n
ot ap
plic
able
I-8
3 TUNNEL BORING MACHINE(TBM)
3.1 Machine Specifications
3.1.1. Essential parts of TBMTBMs are normally manufactured in drum-shaped steel shield equipped inside withexcavation and segment erection facilities.The essential parts of the machine include thefollowing items:
i) Rotary cutter head for cutting theground
ii) Hydraulic jacks to maintain aforward pressure on the cutting head
iii) Muck discharging equipment toremove the excavated muck
iv) Segment election equipment at therear of the machine
v) Grouting equipment to fill the voidsbehind the segments, which is created bythe over excavation.
3.1.2. Structure of TBMTBM is composed of the steel shell (so calledthe shield) for protection against the outerforces, equipment for excavation of soil andfor the installation of the lining at the rear.The power and control devices are mountedpartly or totally on the trailing car behind themachine, depending on the size and structureof the machine. Steel shell, made of the skinplate and stiffeners, is composed of threeportions; hood, girder and tail portion (seeFig. 3.1).
In case of the closed type machine, hood andgirder portions are separated by a bulkhead.The soil excavated by the cutter head is takeninto the mucking device through the hoodportion. In some cases, man-lock is installedat the bulkhead in order to change the cutterbits or to remove obstacles under thepneumatic pressure.
For manual type, breasting is provided at thehood portion. The reaction force is supportedby the girder portion where the thrustingdevices are installed.The tail portion of the machine is equippedwith erector of the segments. Tail seal forwater stop is inserted between the skin plateand the segment ring.In case of the articulating system, the girderportion is made flexible by dividing theportion into two or more bodies with pins andjacks. Such flexible separation of the body isadopted to allow a smooth turn along thecurved alignment of the tunnel with differentdiameters of the machines, degrees ofallowance of over cutting and under varioussoil conditions,.When two tunneling machines are connectedunderground, the alignments and the relativepositions of the two machines have to becarefully monitored and adjusted. The finalconnection normally requires some soilimprovement work such as ground freezing,or else with extendable cutter head or hoodequipped on either one of the machines.
Fig. 3.1 Components of Tunneling Machine
I-9
3.1.3. Types of TBMs for soft groundAs described in the previous section, TBMsfor soft ground are classified into three types;earth pressure type, slurry type andmechanical type. These three types of TBMsare summarized in Fig 3.2. Before thosethree types were developed, other types of
TBMs such as the open type, blind type,manual type, and half-mechanical type wereused for soft ground. The open type TBM isnow mostly replaced by closed type for softground tunneling.
Fig. 3.2 Type of TBM for Soft Ground
3.1.4. Selection of TBMCareful and comprehensive analysis should bemade to select proper machine for soft groundtunneling taking into considerations itsreliability, safety, cost efficiency and theworking conditions. In particular, thefollowing factors should be analyzed:
i) Suitability to the anticipatedgeological conditions
ii) Applicability of supplementarysupporting methods, if necessary
iii) Tunnel alignment and lengthiv) Availability of spaces necessary for
auxiliary facilities behind the machine andaround the access tunnels
v) Safety of tunneling and other relatedworks.
Fig. 3.3 indicates a flow chart for selectingTBM for soft ground. In selecting the type ofTBM, it is important to consider geological andgroundwater conditions that affect the stabilityof the tunnel face. Geological condition along the tunnel route isa primary factor to be considered for selecting
the type of machine. Particularly, the degree ofconsolidation of the ground and the size ofgravel and boulders in the soil should bethoroughly investigated. Table 3.1 shows thegeneral relationship between the closed type oftunneling machine and soil conditions. In acase where a tunnel is very long or is undercomplex geological conditions, uniform layerscould not be expected throughout the entirelength of the tunnel. In such case, a tunnelingmethod is selected based on the geologicalcondition prevailing throughout the tunnel.Special attention should be paid to thefollowing local geological conditions: i) Soft clayey soil that is sensitive and easy tocollapse ii) Sand and gravel layers with high watercontents iii) Layers which contain boulders iv) Layers which may contain driftwood orruins v) Strata which are composed of both soft andhard layers
Slurry type is easy to be automaticallycontrolled and is the most advanced excavation
(Tunnel face stabilization)
Excavate soil + face plate
Excavate soil + spokeplate stabili ingExcavate soil + additives + face plate
Excavate soil + additives + spoke
Slurry + face platestabilizingSlurry + spoke
Bulkhead
Hood
Breasting
Hood
Breasting
Face plate
Spoke
Earth pressure
High-density slurry
Earth pressure type
Slurry type
Blind type
Manual
Half mechanical
Mechanical
Fully open
Partially open
Open
Closed
TBM
I-10
method for soft ground tunneling because of itsreliability, safety and the minimum disturbanceto surrounding ground.Both earth pressure balance type and slurrytype generally does not require supplementarysupporting methods under ordinary conditions.The supplementary methods should beconsidered, however, for tunneling at starting
and arrival area where the face of the tunnel isdifficult to be stabilized. Also, somesupplementary methods such as chemicalgrouting, ground freezing, pneumatic pressureand boulder crushing are required to drivethrough grounds with boulders or gravel, underthin overburden or any other special conditions.
Fig. 3.3 Flow Chart for Selecting TBM for Soft Ground
Site Investigation
Investigation for Route SelectionConditions of the Plan, Geological Conditions, Conditions of Construction, etc.
Prel
imin
ary
Inve
stig
atio
n
Investigation for ConstructionFace Stability, Ground Settlement, Environmental Preservation, etc.
Geology,
Bas
ic I
nves
tigat
ion
FaceYes No
Mechanized Excavation TypeEarth Pressure Balance Type
Slurry Type
Investigation of Additional Countermeasures
Investigation of Ground Settlement
Selection of Construction Method
Comparison of TBM Type
Selection of TBM Type
Det
aile
d In
vest
igat
ion
I-11
Tabl
e 3.1
Rel
atio
nshi
p bet
wee
n C
lose
d T
ype
Tunn
elin
g M
achi
ne a
nd S
oil C
ondi
tion
s
Ear
th p
ress
ure b
alan
ce ty
peE
arth
pre
ssur
e typ
eH
igh-
dens
ity sl
urry
type
Slur
ry ty
peTy
pe o
f mac
hine
Soil
cond
ition
sN
-val
ueSu
itabi
lity
Che
ck p
oint
Suita
bilit
yC
heck
poi
ntSu
itabi
lity
Che
ck p
oint
Mol
d0
x_
sse
ttlem
ent
sSe
ttlem
ent
Silt,
Cla
y0
– 2
l_
l_
l_
Sand
y si
lt0
– 5
l_
l_
l_
Allu
vial
clay
Sand
y cl
ay5
– 10
l_
l_
l_
Loa
m, C
lay
10 –
20
sJa
mm
ing
byex
cava
ted
soil
l_
l_
Sand
y lo
am15
– 2
0s
ditto
l_
l_
Dilu
vial
clay
Sand
y cl
ayO
ver 2
5s
ditto
l_
l_
Solid
cla
ySo
lid c
lay
( m
uddy
pan
)O
ver
50s
ditto
sW
ear
of b
its
Wea
r of
bit
Sand
with
silty
cla
y10
– 1
5l
_l
_l
_
Loo
se sa
nd10
- 3
0s
Con
tent
of c
laye
yso
ill
_l
_Sa
nd
Com
pact
sand
Ove
r 30
sdi
ttol
_l
_L
oose
gra
vel
10 –
40
sdi
ttol
_l
_
Com
pact
gra
vel
Ove
r 40
sH
igh
wat
erpr
essu
rel
_l
_
Gra
vel w
ith c
obbl
est
one
_s
Jam
min
g of
scr
ewco
nvey
orl
_s
Wea
r of
bit
Gra
vel
Cob
ble
ston
eL
arge
gra
vel
Cob
ble s
tone
_s
Wea
r of
bit
sW
ear
of b
its
Cru
shin
g dev
ice
l :n
orm
ally
appl
icab
les:
appl
icab
le w
ith s
uppl
emen
tary
mea
nsx
:not
suita
ble
I-12
3.2 Orientation and operation of machine
3.2.1. Excavation Control SystemSince the closed type machine was developed,tunnel excavation has been mostly controlledby computerized system rather than manually.In addition, various supporting systemsnecessary for tunneling operation requiresophisticated controlling system. A real timecomputerized system equipped with varioussensors is developed for tunneling, in whichorientation and operation of machine,excavation, backfill grouting and operation ofauxiliary facilities are controlled by acentralized computer system. The systemrealized accurate alignment, excavation controlthat maintains the stability of the face of thetunnel, and minimized the disturbance of thesurrounding ground. For slurry type tunnelingmachine, operation of pumps and valves forslurry transportation is computerized based onthe data fed by pressure gauges, flow metersand other measuring devices for fluidtransportation. Thus, steady pressure of slurryis maintained throughout the tunnelingoperation.
In the near future, all operation of the machinewill be entirely controlled by computerizedsystem from above ground.
3.2.2. Direction Control and MeasurementSystemAutomatic direction control system has beenput to practical use that utilizes survey dataobtained by real time measurement deviceinstead of the conventional transit-level survey.The system consists of measurement anddirection control systems, and comprises offour functions; survey, monitor, analysis andcontrol. The measurement system utilizes laserbeam (laser, infrared or diode) or gyrocompass,and measures the location of the machine inthree-dimensional coordinates and its attitude(pitching, rolling and yawing).
Direction of the machine is normally controlledby jacks that introduce proper thrust force androtation moment. Each jack on a cutter disk iscontrolled by a computerized system based onthe target amount of thrust and the direction ofmachine. In the process of determining theamount of thrust required for each individual
jack, a mathematical theory of “fuzzy controltheory” has been applied based on the dateaccumulated through the past performance ofthe machine. Recent automatic directioncontrol system realizes accuracy of plus orminus 30 mm both horizontally and vertically.
3.3 Cutter Consumption
3.3.1. Bit types and ArrangementThere are several types of bits for TBM, suchas teeth bit, peripheral bit, center bits, gougingbit, wearing detection bit, etc. Bits aregenerally made by steel or hard chip alloy thatis highly wear resistant. Selection of materialand types of bits is made based on the groundconditions, excavation speed andlength of the tunnel. Arrangement of bitson the cutter head is decided based onconstruction conditions, past experiencein similar geology, cutting depth and thenumber of passes of rotating bits.
3.3.2. Wear of BitGenerally, the amount of wear of bits isproportional to the product of number of passesof rotating bits and length per pass, and isinfluenced by ground conditions and otherfactors such as type of machine, geology,material and arrangement of the bits on a cutterhead. The amount of wear can be estimated bythe following formula;
d =(K.π.D.N.L)here, d: amount of wear (mm) K: wear coefficient (mm / km) D: distance between the center of cutterdisk and bit (m) N: number of revolution of cutter disk perminute (rpm) L: excavation distance (m) V: rate of excavation (mm / min)
The wear coefficient, K, above is given bymanufacturers based on the pressure applied tobits, the rotating speed, geological conditions,number of passes and material of bits to beused.
3.3.3. Long Distance ExcavationSometimes, a tunneling machine is required todrive through entire length of tunnel whenaccess tunnels for installation of two or more
I-13
machines cannot be constructed due to the lackof land available. In that case, the tunnelingmachine, especially the cutting bit and tail seal,is required to be highly durable. For higher durability of the bits, new chippingmaterial such as hard chip alloy has beendeveloped, which are two or three timesdurable than those of conventional material.Bits can be changed from inside the TBM.Durability of tail seals and the method ofchanging them are being improved as well.
3.4 Ground Support and Lining
3.4.1. Design of LiningThe linings of the tunnel must withstand thesoil and water pressure acting on the tunnel.Primary tunnel lining is usually constructed byprefabricated concrete segments erected aroundthe periphery of the tunnel. Those segmentsare connected each other to form circular ringswhich are installed side by side continuously toform a cylinder. The second lining, whenrequired, is normally constructed by in-situconcrete.
Usually primary lining is designed as a mainstructural member against the final load,because the secondary lining is installed long
after the erection of segments. Therefore, therole of the secondary lining is mostly notfor the main structural member, but forthe supplementary member for waterproofing, anticorrosion, etc. Secondarylining is omitted to save costs when theprimary lining is watertight enough or theground conditions are favorable.
For the design of the segment, several loadsand their combination should be considered(see Table 3.2). Temporary loads that varyduring the construction such as thrust force byjacks and grouting pressure should be alsotaken into consideration.
The effects of joints between segments andrings should be carefully assessed whendesigning segment lining. As several segmentsare pieced together to produce a ring, the ringmay not deform uniformly against thesurrounding loads due to weakness at segmentjoints. The same can be said to the jointsbetween rings. Staggered arrangement is madeto reduce these effects of the joints.
Under present design method, segment ringassumes to be a uniform flexural ring, a multi-hinged ring or a ring with rotational springs.
Table 3.2 Loads on Segments
Main load vertical and horizontal earth pressurewater pressure
dead loadsurcharge loadground reaction
Secondary load internal loadtemporary load during execution
seismic loadspecial load Influences of adjacent tunnel
of adjacent structuresof ground settlement others
3.4.2. Types of SegmentAs the cost of segments shares significantportion of total tunneling cost, type of segmentshould be carefully selected from bothengineering and economical points of view.Segments are classified into several types;reinforced concrete (RC), steel, cast iron(ductile), composite, and others.
Reinforced concrete prefabricated segmentsare most commonly used for tunnels driven byTBMs. Reinforced concrete segment is anexcellent lining member with highcompressive strength against both radial andlongitudinal forces. It also has high rigidityand water tightness. On the other hand, it isheavy and has less tensile strength and morefragile than steel ones. Therefore, extremecare should be taken to the removal of forms
I-14
during fabrication and to the erection duringconstruction in order to avoid possibledamages to segments, especially to theircorners. Rectangular shaped segments arecommonly used, but hexagonal or othershapes are also produced. They can be eithersolid or box type.
Steel segment is flexible and is relatively lightand easy in handling. Because of theflexibility of steel segment, they should not besubjected to high thrusting force of jacks orgrouting pressure to avoid buckling orunnecessary deformation. When the secondlining is omitted, proper anticorrosionmeasures should be taken.
Cast iron (ductile) segment is produced withprecise dimensions and therefore can beerected with good water tightness. Because ofits strength and durability, it is commonlyused at locations under heavy loads or forreinforcing tunnel openings.
In addition to above three types of segments,
various types have been used or proposed,such as composite segments (steel and RC,steel and plain concrete), flexible segment thatallows certain degree of deformation causedby earthquake or uneven ground settlement.Also, there are several types of radial andlongitudinal segment joints such as bolt,cotter, pin and pivot, knuckle and other jointtypes.
3.4.3. Fabrication of SegmentFabrication of segments has to be carried outunder strict quality control to ensurecompliance with specified dimensions andstrength. Automated fabrication of segmentsis desired that provide adequate qualitycontrol to ensure structural integrity andprecise dimensions of segments.Table 3.3 provides allowable stresses ofconcrete for pre-fabricated reinforcedconcrete segment.
Table 3.4 provides typical dimensions ofsteel and concrete segments.
Table 3.3 Allowable stresses of concrete for pre-fabricated concrete segments
Allowable stress (N/mm)
Design compressive strength 42 45 48 51 54
Bending compressive stress 16 17 18 19 20Shearing stress 0.71 0.73 0.74 0.76 0.77Bonding stress to deformed re-bar 2.0 2.1 2.1 2.2 2.2Bearing stress (overall load) 15 16 17 18 19
I-15
Table 3.4 Typical Dimensions of Segments (mm)
Steel Segment Concrete SegmentOuter Diameter Width Thickness NO/Ring Width Thickness NO/Ring1,800 _ 2,000 750 75
1006 900 100
1255
2,150 _ 2,550 9001,000
100125
6
2,750 _ 3,350 9001,000
125150175
6
9001,000
100125150
5
3,550 _ 4,050 9001,000
125200225
7
4,300 _ 4,800 9001,000
150175
7
9001,000
125150175200
6
5,100 _ 5,700 9001,000
175200225
7
6,000 9001,000
200225
7
9001,000
175200225250275300
6
6,300 _ 6,900 9001,000
250275
7 9001,000
250275300
7
7,250 _ 8,300 9001,000
300325350
8 9001,000
275300325350
8
3.4.4. Erection of SegmentsThe process of primary lining consists oftransportation and erection of segments.Segments are usually transported through thetunnel by cars on rails. Automatictransportation system of segments is used torecent projects that transport segments from adepot above ground to the rear end of themachine through access shaft and tunnel.
The erection of segments is done by anerector at the rear room of the machine. Thesegment erector is equipped with gripping,shifting, rotating and setting devices.Longitudinal joints of segment rings arenormally made manually.
3.5 Auxiliary Facilities
Generally, tunneling operation by TBMconsists of cutting ground by cutter head,jacking to push machine forward, mucktransportation, segment erection and groutingof voids behind segments. Auxiliary facilitiesthat are typically required throughout thisoperation are shown in Table 3.5.Common facilities are gravel treatment plant,grouting facilities, segment depot andtreatment facilities. For the discharge ofexcavated muck, different types of facilitiesare required depending on the type oftunneling machines as follows.
I-16
3.5.1. Earth pressure balance typemachineThe excavated muck is removed from thecutter chamber by a screw conveyor and sentout by mucking car or belt conveyor. Forsmall diameter tunnels where working spaceis quite limited, the excavated muck is mixedwith plasticizer and pumped out through thepipe. For these operations, additive mixingplant, a screw conveyor and belt conveyor ormucking cars are required.
3.5.2. Slurry type tunneling machineSequence of discharging the excavated muckfor this type of machine consists of; (i)pouring slurry to the cutter chamber while thesoil is excavated and the machine is pushedforward, (ii) mixing excavated soil with slurryand pumping the slurry mix from the cutterchamber to a treatment plant where the slurrymix is separated into soil and slurry, (iii)discharging the separated soil out to thedisposal area and circulating the slurry backto the tunnel face for reuse. Auxiliaryfacilities required for these operations areslurry mixer, feed and discharge pumps andpipes, and slurry treatment plant.
Table 3.5 Auxiliary Facilities
Earth pressure balance type Slurry type- Segment pool and transportation facilities for segments and materials- Central control room- Gravel treatment facilities, such as crushing device- Grouting facilities for back fill- Belt conveyor, mucking cars or pumps- Additive mixing plants
- Slurry transport facilities, such as slurrypumps and pipes.
- Slurry treatment facilities, such ascentrifugal classifier and filter plant
I-21
4.3 Size of TBM
4.3.1. Weight
Fig. 4.5 Diameter and weight of TBM (EPB, Slurry)
4.3.2. Length/Diameter (L/D)
Fig. 4.6 Diameter and length/diameter (L/D) of TBM
I-22
APPENDIX: TBM PERFORMANCE INHARD ROCK
A-1 General
The following prognosis model is a summaryof “Project Report 1-94, Hard Rock TunnelBoring”, published by University ofTrondheim, The Norwegian University ofScience and Technology, NTH Anleggsdrift.
The prognosis model is based on job sitestudies and statistics from 33 job sites with 230km of bored tunnels in Norway and othercountries. Data have been carefully mapped,systematized and normalized and the presentedresults are regarded as representative for wellorganized tunneling. It should be noted thatthe prognosis model is valid for parametervalues in the normal range. Extreme valuesmay, even if they are correct, not fit the modeland give incorrect estimates.
The prognosis model has been developedcontinuously since 1975 and has in the periodup till now been through several phases and
adjustments in accordance with increasedknowledge and improvements of TBMs,auxiliaries and methods. The model is todayconsidered as a practical and useful tool forpre-calculation of time consumption and costsfor TBM bored tunnels in hard rock. Themodel is based on the use of TBM, Open type.
A-2 Advance
A-2.1 Rock Mass Properties1. DRILLING RATE INDEX, DRI: Indexrelated to the properties of the rock mass.Together with Fracturing, DRI is the rock massfactor that has the major influence onPenetration Rate.DRI is calculated from two laboratory tests,- the Brittlenes Value S20- Sievers J-Value SJThe two tests give measures for the rock’sability to resist crushing from repeated impactsand for the surface hardness of the rock.Recorded Drilling Rate Indexes for some rocktypes are shown in Fig. A.1.
Fig. A.1 Recorded Drilling Rate Index for various rock types
2. CUTTER LIFE INDEX, CLI: Cutter LifeIndex is calculated on the basis of Sievers J-Value and the Abrassion Value steel. ( AVS.)
CLI expresses the lifetime in boring hours forcutter rings of steel on TBM. Recorded CLIfor some rock types are shown in Fig.A.2
I-23
Fig.A.2 Recorded Cutter Life Index for various rock types
3. FRACTURING: The most importantpenetration parameter for tunnel boring. In thiscontext, fracturing means fissures and jointswith little or no shear strength along the planesof weakness. The less the distance between thefractures is, the greater the influence on thepenetration rate. Rock mass fracturing ischaracterized by degree of fracturing (type andspacing) and the angle between the tunnel axisand the planes of weakness.
a) JOINTS in this respect are fractures that canbe followed all around the tunnel profile.
b) FISSURES are non-continuous fractureswhich can be followed only partly aroundthe tunnel profile.
c) FRACTURING is recorded in CLASSESwith reference to the distance between theplanes of weakness. The classes are shown inFig. A.3. Recorded fracturing for some rocktypes are shown in.
Fig. A.3 Fracture classes with corresponding distance between planes of weakness
I-24
Fig. A.4 Recorded degree of fracturing for various rock types
d) FRACTURING FACTOR, Ks combines theeffect of the fracturing class and the anglebetween tunnel axis and planes of weakness.See Fig.A.5. The factor Ks is used in aformula for calculation of penetration rate.
e) EQUIVALENT FRACTURING FACTORexpresses the rock mass properties as theFracturing Factor Ks adjusted for DRI-value.See Fig.A.5. KEQV = Ks x KDRI
Fig. A.5 Fracturing factor, Correction factor for DRI≠49
I-25
A-2.2 Machine Parameters1. BASIC CUTTER THRUST: (MB) The grossthrust of the TBM divided by number ofcutters, N. Thus, for practical calculatingpurpose the CUTTER THRUST in this modelmeans the average thrust of all the cutters onthe cutter head (kN/cutter). The friction
between TBM and rock mass is disregarded.Recommended max. gross average thrust forTBMs with different diameters and cutterdiameters are shown in Fig. A.6. Forcalculation of penetration the cutter diameterand cutter spacing must be taken into account.
Fig. A.6 Recommended max. gross average per disc
2. CUTTER SPACING: The averagedistance between the cutter tracks on the face =Diameter of TBM /2N (N= number ofcutters)._CUTTER SPACING is normallyabout 70 mm.3. CUTTER HEAD R.P.M.: Revolutions per.
Minute. Cutter head r.p.m. is inverseproportional to the cutter head diameter. This isin order to limit the rolling velocity of theperipheral cutters. Cutter head r.p.m. asfunction of TBM diameter is shown in Fig. A.7.
Fig. A.7 Cutterhead r.p.m. as function of TBM-diameter
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4. INSTALLED POWER ON CUTTERHEAD: (kW) The rated output of the motorsthat are installed to give the cutter head itstorque. The rolling resistance and thus thetorque demand increases with increasing netpenetration. The available torque may thereforebe the limiting factor when the penetration ishigh and/or the TBM is boring in veryfractured rock. See 3) (3) TORQUE -DEMAND below.
A-2.3 Other Definitions1. BASIC PENETRATION RATE: BasicPenetration Rate (i) in mm/rev as a function ofequivalent thrust and equivalent fracturingfactor is shown in Fig. A.8. For cutterdiameters and average cutter-spacing differentfrom _=483 mm and 70 mm respectively theequivalent thrust is given by the formula: MEQV
= M x x KDX x KA (kN/cutter)Fig. A.9 and Fig. A.10 give correction factorKd for cutter diameters different from 483 mmand factor KA for cutter spacing.
Fig. A.8 Basic penetration for cutter diameter = 48.3 mm and cutter spacing = 70 mm
I-27
Fig. A.9 Correction factor for cutter diameter≠483 mm
Fig. A.10 Correction factor for average cutter spacing≠70 mm
2. NET PENETRATION RATE: Netpenetration rate (I) is a function ofbasic_penetration and cutter head r.p.m.I = i x r.p.m. x (60/1000) (m/hr)3. TORQUE DEMAND: For calculated highnet penetration or when the rockis_very_fractured, one must check that the
installed power on the cutterhead givessufficient torque to rotate the cutterhead. If notthe thrust must be reduced until the requiredtorque is less than the installed capacity.Necessary torque is given by the followingformula:
I-28
TREQ. =0.59 x rTBM x NTBM x M x kc (kNm)0.59 = Relative position of the average cutter on the cutterhead.RTBM = cutterhead radius.NTBM = number of cutters on the cutterhead.M = Average thrust pr, cutter.Kc = cutting coefficient (for rolling resistance) kc = Cc x i 0.5
Cc is a function of cutter diameter and is found from Fig. A.11.
Fig. A.11 Cutting constant Cc as a function of cutter diameter
4. Other Limitations to Advance RateBesides limitations due to available torque, thesystem’s muck removal capacity may be alimiting factor, particularly for large diametermachines. When boring through marked singlejoints or heavy fractured rock, it may benecessary to reduce the thrust due to too highmachine vibrations and very high momentarycutter loads.
A-2.4 Gross advance rateTHE GROSS ADVANCE RATE is given inmeters per week as an average for a longerperiod. Gross advance rate depends on netpenetration rate, machine utilization and thenumber of working hours during the week.Machine utilization is net boring time inpercent of the total tunneling time. Totaltunneling time includes: Boring TB (Dependson net penetration rate)
- Regripping TT (Depends on stroke length,normally 1.5-2.0 m. As an average 4-5minutes.)
- Cutter change and inspection Tc (Dependson cutter ring life and net penetration rate.Time needed for cutter change may varyfrom 30 to 60 minutes per cutter.)
- Maintenance and service of TBM, TTBM,and back-up equipment TBACK (Timeconsumption for maintenance and repairdepends on net penetration rate asindicated in Fig. A.12.)
- Miscellaneous TA (Miscellaneous includenormal rock support in good rockconditions, waiting for transport, tracks orroadway, surveying or moving of laser,water, ventilation electric cable, cleaning,other things like travel, change of shiftetc.) TA as hours per km is indicated inFig. A.12.
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Fig. A.12 Maintenance as function of net penetration rate
A-2.5 Additional Time ConsumptionEstimation of time consumption for a tunnel isbased on weekly advance rate, estimated on thebasis of net penetration rate and total utilizationof the TBM. In addition, extra time must beadded for- assembly and disassembly of TBM and
back-up equipment in the tunnel- excavation of niches, branches, dump
stations etc.- rock support in zones of poor quality- additional time for unexpected rock mass
conditions- permanent rock support and lining work- downtime due to major machine
breakdowns- dismantling of tracks, ventilation, invert
cleanup etc.
Example of application
Geometrical conditions:Tunnel diameter: f = 4.5 mTunnel length: L= 3200 m
Geological conditions:Type of rock: Mica Schist
Drilling Rate Index: DRI= 60Degree of fracturing: St IIAngle between tunnel axisand planes of weakness: 45Fracturing factor. ks = 1.40
Machine parameters:TBM diameter: f = 4.5 mCutter diameter: 483 mmGross thrust pr. cutter: Fig. A.6
290 kN/cutterCutterhead r.p.m.: Fig. A.7
11.1 rev./min.Number of cutters: 32Average cutter spacing: 70 mmInstalled power: 1720 kW
Net penetration rate:Equivalent thrust: Fig. A.9 and Fig. A.10 MEQV = 290 x 1.00 x 0.975 = 283 kN/cutterBasic penetration: Fig. A.8 i = 8.40 mm/revNet penetration:
8.40 x 11.1 x 60/1000 = 5.59 m/hour
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Torque check:Cutter constant: Fig. A.11
Cc = 0.034Cutting coefficient: kc = 0.034 x 8.400.5 = 0.0985Necessary torque:
Necessary power: PN = 1213 x 2π x 11.1/60 = 1410 kW
A-3 Cutter Consumption
The cutter ring life depends mainly on thefollowing factors:
1. Rock mass properties:- CUTTER LIFE INDEX (CLI), see A-2, 1.
(2)- Content of abrasive minerals in the rock
2. Machine parameters:- Cutter diameter- Cutter type and quality- Cutter head diameter and shape- Cutter head rpm- Number of cutters
The cutter ring life, in boring hours, isproportional to the Cutter Life Index. (CLI)Fig. A.13 shows the basic cutter ring life as afunction of CLI and cutter diameter.Corrections must be made for varyingcutterhead r.p.m. Also for TBM diameter asCenter- and Gauge Cutters have a shorterlifetime than Face Cutters. (Fig. A.14).Corrections must also be made for number ofcutters on TBM (Ntbm) deviating from normal(No). Finally correction must be made toquartz-content.(Fig. A.15)
Average life of cutter rings is thus given thefollowing formulas:Cutter ring life in h/c: HH = (H0 x k f _ x k0 xkRPM x kN)/NTBM
Cutter ring life in m/c: Hm = HH x I (I = netpenetration rate)
I-31
Fig. A.13 Basic cutter ring life as function of CLI and cutter diameter
Fig. A.14 Correction Factor for Cutting Ring Life
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Fig. A.15 Correction Factor for cutting ring vs. Quartz Content
A-4 Troubles and Countermeasures
A-4.1 Causes for Trouble.<<Trouble>> is caused by unforeseen incidentsor conditions that may be difficult to tacklewithin estimated tunneling time. Trouble inhard rock boring come from:- geological conditions- reasons related to the TBM itself and/or
from the rest of the machines andinstallation, - and/or trouble come as aconsequence of lack of experience fromsimilar works and general know-how intunneling.
1. Geological Causesa) Water Inflow is always a factor one shall
have in mind. It counts for everythingfrom occasional appearance of smallamounts of water with no practicalconsequences, to total inundation with freeflowing conditions, some times withmaterial outwash and serious tunnelingproblems. If caught unaware, theseproblems are capable of completelydisrupting tunneling activity andinfluencing the time schedules drastically.This is serious to conventional tunneling, -
it may be even worse to TBM-tunnelingwith all the sophisticated electricalinstallations.
Water may come from groundwater, ores,leakage through the overburden from lakes,rivers etc. or even from underground lakes orfrom Artesian wells. Inflow of salt water maybe damaging even in small amounts and callsfor special precautions.It creates a special atmosphere in the tunnelwith damaging effect to the electricalequipment and rust and corrosion to the steelconstruction if not taken care of.
b) Boring in Hard Rock means normally boringin Sound, Solid Rock, and <<open>> TBMsare normally chosen. Nevertheless it is notunusual to meet Faulty Fractured Zones,Unconsolidated Weak Rock, Swelling Ground,Squeezing Ground and very often so calledMixed Faces which means that face consistspartly of hard massive rock and partly offractured rock. Even one single significantfracture may influence the drillability.Consequences to the boring may naturally varyfrom minor problems to the penetration rate tofull stop with TBM stuck in the tunnel.
I-33
Swelling Ground very often comes from theinfluence of special rock materials as so calledswelling clay which starts swelling whenexposed to humidity. It may cause down-falland dangerous conditions. Squeezing Groundis found in tunnels in soft rock with largeoverburdens, and consequently high rockpressure. Rock deformations may in extremecases lead to total closing of the tunnel.
c) Even if TBM- technology and –know how issteadily improving and thus extending theframe as far as the geology and thegeological parameters are concerned, thereare still limits. The drillability is a functionof a number of rock parameters, out ofwhich fracturing and rock hardness are themost important. It is rare to get into rockwhich is so hard and so massive that boringis technically impossible with the mostpowerful TBMs on the market to day, but itmay be a challenge to the economy.
If pre-investigations reveal occurrence of rockwith the above properties it will be a matter ofcalculation to find out if the available TBM isable to do the job, and in case, -what will bethe advance rate and what will be the cost. Theabove calculation model should be usedcarefully in this case since it is based onexperiences from rock with not extremeproperties, but it will normally be goodenough. If the rock shows up unexpectedparameters one might be in trouble if the TBMis too weak, and/or the cutters have insufficientquality.
d) High Temperature Ground is found indifferent parts of the world as for instance inthe Alps, in tropical areas and/or when thetunnel goes with extreme overburden as inmines. The temperature is seldom a realobstacle to the boring itself as long as oil ischosen accordingly and cooling water formotors and cutters are available in sufficientquantities, but rather a challenge to the crew.
e) Combustible gases like methane and dustwith high content of coal are dangerous andmust be taken care of properly.
2. Machine Related TroublesAs is understood from the above a good resultwith respect to advance rates and tunnel-meter-
costs are to a very great extent dependent onthe TBM and the supplementary equipment.The geology related conditions in a tunnel arefixed as such. The result of the tunneling withrespect to advance rate and tunnel-meter-cost istherefore in fact a question of doing the rightchoice of TBM and equipment and to beprepared for conditions as they appear.
The right choice of TBM and supplementaryequipment is not only a question of looking atmachine specifications. It is also a question towhich extent it is possible to utilize the samemachine parameters. It is an experience fromhard rock boring that the TBMs have morepower than can actually be utilized becausecomponents like for instance cutters in practiceare not strong enough.Breakdowns due to Main Bearing failure or dueto failure on other important and expensivecomponents or parts are naturally disastrous totime schedule and costs. (To change a mainbearing may take from four to six weeks,provided the bearing is available.) Downtimecaused by unskilled operation of themachinery, bad maintenance and repair,waiting for supply of spares, bad ventilation,cut in power supply, waiting for muck-transport, cutter change and cutter inspectionshould always be encountered and as far aspossible be avoided or minimized.
A-4.2 Countermeasures1. For trouble caused by water inflow there arebasically two ways to go.- To stop the water before it gets into the
tunnel by Grouting Ahead of the Face forwhich purpose boring equipment has to beinstalled. The equipment should be able tomake a 360°funnel with at least 25 m longholes for grouting.
- To take care of the water when it is in thetunnel by Increased Drainage Capacity.What is the best is depending on theamount of water and where it comes from.If the inflow effects change in groundwater level and/or pressure grouting maybe required. Large inflow of water maycause damage to the machinery, and to theelectrical installation in particular, andprotection of exposed components may berequired.
I-34
2. Countermeasures to unusual and unsoundground depends on the actual caseRock Bolting, Fiber-reinforced Shotcrete aloneor together with Rock Bolts, Grouting or in situCasting with Concrete or may be necessary.The real trouble comes if the equipment is notbuilt for installation of necessary equipment tocarry out the rock support in an efficient way.Fractures are discontinuities in the rock mass.The fractures are described by thickness,length, distance between the fractures,roughness in planes of weakness, sort ofmaterials found in the fractures, if they areresults of bedding or foliation, and strike anddip if there is a definable pattern. Fractures inthe rock mass are an advantage with respect toadvance rates as long as rock support is notrequired.The above factors are strongly into the picturein the so called Q-method which is a method todefine the rock mass quality with respect tostability and the need for rock support. Variousclasses of rock mass quality which go fromexceptionally good to exceptionally poor willrequire from no support at all, spot bolting,systematic bolting, shotcrete etc. to castconcrete lining.
3. Too Hard Rock is normally a cutter-problem.The cutters are spoiling and/or heavily wornand the penetration rate is reduced. Due tofrequent cutter inspections and -changes theutility time goes down and consequently alsothe Gross Advance Rate.Great efforts are constantly made to increasethe cutter quality. Much is achieved byimproving the steel quality in the rings and byincreasing the size of the cutters and thus beable to use bigger and better bearings.To change the size of cutters is theoretical, butnormally not a practical solution to meet asection of too hard rock in a tunnel.If the <<too hard rock>> problem seems to bepermanent it is a possibility to call for a specialstudy of the rock in order to improve the cutter-result and/or to call for competing suppliers ofcutters.Cutters with tungsten-carbide inserts areexpensive, but may be the solution for a shortperiod. Tungsten-carbide inserted cutters canalso be used together with normal cutters inpositions that are most exposed, for instance asgauge cutters.
4. High Temperatures in the tunnelIn tropical areas the outdoor temperature mayalso be very high, at least during daytime.Cooling of the ventilation air will therefore bea necessity in such areas. Together with thecooling effect from the evaporation of theflushing water it is absolutely possible toachieve livable temperatures.
5. Combustible GasesThe TBM itself and supplementary machineryand all electrical installation must be insulatedto prevent any explosion to come from sparklesor heating. Gas Detection instruments must beinstalled.In dimensioning of the ventilation system theoccurrence of gases and dust must be taken intoconsideration.In countries where the above are frequentoccurrences there are normally very strictregulations with regards to what to do toprevent explosion and also what to do if theaccident should happen.Dust with quartz appears frequently inconnection with hard rock boring. It is notcombustible, but a serious hazard to the healthif breathed for a long period. It is partly aventilation matter to remove the dust from theworking area, and partly.
Germany, Switzerland and Austria
Tunnelvortriebsmaschinen Tunnel Boring Machines
Empfehlungen zur Auswahl und Bewertung von Tunnelvortriebsmaschinen
Recommendations
for
Selecting and Evaluating Tunnel Boring machines
DAUB
Deutscher Ausschuss für unterirdisches Bauen (DAUB)Österreichische Gesellschaft für Geomechanik (ÖGG) undArbeitsgruppe Tunnelbau der Forschungsgesellschaft fürdas Verkehrs- und Strass enwesenFGU Fachgruppe für Untertagbau Schweizerischer lngenieur-und Architekten-Verein
II-ii
1. Purpose of the recommendations......................................................................................................12. Geotechnics .........................................................................................................................................13. Construction methods for mined tunnels.........................................................................................2
3.1. Survey..........................................................................................................................................23.2. Explanation of the Construction Methods..............................................................................3
4. Tunneling machines TM....................................................................................................................54.1. Tunnel Boring Machines (TBM) .............................................................................................5
4.1.1. Tunnel boring machines without shields .......................................................................54.1.2. Tunnel boring machines with shields TBM-S...............................................................5
4.2. Shield Machines SM .................................................................................................................54.2.1. Shield Machines with full-face excavation SM-V........................................................54.2.2. Shield machines with partial axe excavation SM-T .....................................................7
4.3. Adaptable dual purpose shield machines................................................................................94.4. Special forms..............................................................................................................................9
4.4.1. Finger shields.....................................................................................................................94.4.2. Shields with multi-circular cross-sections .....................................................................94.4.3. Articulated shields.............................................................................................................94.4.4. Cowl shield ........................................................................................................................94.4.5. Displacement shield..........................................................................................................94.4.6. Telescopic Shields.............................................................................................................9
4.5. Supporting and lining..............................................................................................................104.5.1. Tunnel boring machines TBM.......................................................................................104.5.2. Tunnel boring machines with shield TBM-S and shield machines SM ..................10
5. Relationship between geotechnics and tunneling machines.......................................................115.1. Ranges of application for tunneling machines.....................................................................115.2. Important selection and evaluation criteria ..........................................................................125.3. Pointers for special geotechnical and constructional conditions.......................................15
II-1
1. Purpose of the recommendations
The developments in mined tunneling arecharacterized by an increased trend towardsfully mechanized tunneling with appropriatetunneling machines (TBM) in solid rock andsoft ground. The creation of special methodssuch as face supporting with fluid or slurry aswell as the successful utilization of cutter discsfor removing rock-like intrusions and bouldershave led to a considerable expansion of thefield of application and to an increase in theeconomy of these tunneling systems.The increasing application of tunnelingmachines and the related continuousimprovement of the various extractiontechniques had led to types of machines, whichhave the capacity to penetrate extremelyheterogeneous subsoil, that is respectively amixture of soft ground and solid rock. Theclear distinction between tunnel boringmachines (TBM) for solid rock and shieldmachines (SM) for soft ground, which resultedfrom their conceptional background and thespecial engineering and extraction technology,has lost its original significance. Pastdevelopments and the progress made inpractice have produced tunneling machines, inwhich the typical features of both techniqueshave been integrated in a single unit. In thisway, the possibility has been created to makeavailable tunneling machines suitable for theentire geotechnical spectrum.The anticipated geotechnical conditions inconjunction with the course of the route andgradient represent the decisive prerequisites forselecting the tunneling method. By comparisonof the cross-section needed for the purpose ofthe tunnel, its length and the geotechnicalconditions with the available technology, themost suitable tunneling machine can bedevised. These recommendations apply tointer-relationships, which exist between thegeotechnical circumstances and process andengineering techniques.When selecting tunneling machines, theenvironmental compatibility of the tunnelingmethods must also be taken into consideration.These recommendations should also be seen asan additional aid, designed to serve theengineer in arriving at a decision. A project-related analysis is, however, essential and
represents the main basis for the approach.These recommendations do not apply, or onlyto a certain extent for micro tunneling.
2. Geotechnics
The knowledge of the geotechnical conditionsis the most important principle for the planningand execution of a tunneling project. Theevaluation of general and special maps leads toinitial recognition about the geological andhydrogeological conditions and providepointers for further investigatory measures. Bymeans of suitable preliminary explorations, thenature and features of the subsoil that must bepenetrated during the construction of a tunnelcan be described. The accuracy of thisdescription depends on the type and extent ofthese pre-investigations as well as theirvalidity. Extremely variable geologicalconditions call for more intensive ofpreliminary surveys.Conditions which restrict thepre-investigations lead to a limited validity of ageotechnical report. This must be taken intoaccount when assessing the projectedgeotechnical conditions. The aim of thegeotechnical survey must be to present thegeological and hydrogeological conditionsrequired for the tunneling project ascomprehensively and lucidly as possible.The subsoil that has to be penetrated is, by andlarge, examined by means of:_ investigatory boreholes and the obtaining ofbore samples and cores_ exploration and sample-taking on the surface_ dynamic penetration tests, pressure probes_ mechanical borehole examinations, e.g.borehole expansion tests, pressiometer_ geophysical investigation methods_ pump and water injection tests_ exploratory tunnelsThrough these investigations and, above all,through the samples that were taken,characteristic values are obtained or derivedthrough further suitable investigations andcorresponding evaluations.The more comprehensively the preliminaryinvestigations are carried out and the morevalid they are the better the basis for selectingthe tunneling method and the tunneling
II-2
machines.The essential geotechnical parameters arelisted in the following:
solid rock- compressive strength (rock strength)- tensile strength, cleavage strength- shearing strength- break and bedding planes- degree of decomposition, degree of
weathering- fault zones- mineralogy/petrography- proportions of abrasive minerals- wearing hardness/hardness- water-bearing and water pressure (under-
ground water)- chemical analysis of the water
soft ground- grain distribution curves- angle of friction- cohesion- deposit thickness- compressive strength- shearing strength- pore volume- plasticity- swelling behavior- permeability- natural and artificial intrusions and faults- water-bearing and water pressure (ground
water)- chemical analysis of the water
special features- primary stress state- rock burst- fault zones- weakening due to leaching processes- heaving/swelling rock- subsidence and subsidence chimneys- karst manifestations- gases- rock temperature- seismic actionMore detailed information relating toinvestigating the subsoil is contained in DIN4020-Geotechnical Invest igat ions forConstruction Purposes. Further pointers arecontained in the “Recommendations forTunneling - Chapter 3: GeotechnicalInvestigations” , published by the DGGT.From the cited geotechnical characteristic
values and an overall appraisal of thegeological and hydrogeological conditions ofthe subsoil, generally speaking, the followingextremely important technical data can beobtained:- ease of break-out of the subsoil- stability of the subsoil- stability of the face- measures for supporting the face- nature and extent of the supporting measures- time lag between breaking-out and securing
the subsoil- deformation behavior of the subsoil- influence of underground and/or groundwater- abrasiveness of the subsoil- stickiness of the excavated soil- separability of the excavated soil (when using
a supporting fluid)- suitability for reutilization of the excavated
soil
Factors, which influence the environment,must also be observed, such as e.g.:- surface settlements- interference with and changes to
the groundwater conditions- suitability of the excavated material for
landfill- contamination of the subsoil and groundwater- health-jeopardizing influencesOn the basis of the listed geotechnicalcharacteristic values and constructional dataincluding the environmentally relevant factors,it is possible the select the construction methodand to divide the tunnel over its route intotunneling classes, which closely define thetunneling method, identify the performances tobe applied per tunneling class and describe thedegree of difficulty. Whereas the selection ofthe construction method is the prerequisite forallocation into tunneling classes (laid down bythe client), the choice of the machine should beleft open as far as possible and left up to theresponsible contractor (choice of theconstruction company).
3 . Construction methods for minedtunnels
3.1. SurveyDifferent construction methods are availablefor executing a tunnel by mining. They can besplit up into the groups-universal headings,
II-3
mechanical headings (tunneling machines) andmicro-tunnel headings. In this connection,those methods for which the extraction resp,the cutting phase is decisive are allocated tosolid rock. In the case of soft ground, on theother hand, the supporting and/or securing ofthe subsoil is accorded priority(Fig.1).In conjunction with the special demandsplaced on a tunnel and taking environmentalfactors into consideration, a general assessmentof the tunneling methods with respect to theirsuitability in individual cases can be carriedout.The remainder of these recommendations dealexclusively with the process technical featuresto be considered when using tunnelingmachines, and essential selection andevaluation criteria for the correspondinggeotechnical fields of application.
3.2. Explanation of the ConstructionMethods
The “shotcreting construction method” is anindependent method, whose possibilities orrather principles of supporting the cavitycombine with various tunneling methods.Under the term “tunneling with systematicallyadvancing support”, we understand tunnelingmethod which embrace the systematic and thusnot simply the partial application of suitablesupporting means, which are applied for theadvance stabilization of the face area. Theseinclude: the forepoling method, methods withpipe screens, screens comprising injectionlances, screens with freezing lances, screenscomprising horizontal HPG columns.Large-area freezing or grouting is methodsdesigned to improve the subsoil, which thenfacilitate the application of a constructionmethod such as shotcreting. The tunnelingclassification then relates to the improvedsubsoil conditions.Whereas the form and size of the cross-sectionin the case of the “universal headings” can beas desired and in fact, can alter within a lengthof tunnel, this flexibility does not exist whentunneling machines are applied.Generally speaking, tunneling machines inaccordance with their function are circular andthus possess a given shape. This restricts theirapplication should the utilization of a circularcross-section not be purposeful or necessaryand therefore, increases the costs. Tunnelingmachines have also been developed which do
not drive circular cross-sections.Tunneling machines are, by and large, gearedto their diameter. This applies, first andforemost, to shield machines. In the case oftunneling machines for solid rock, a certainvariation of the diameter is possible if a shieldbody is not required.Recent developments allow shield machines tobe modified for different diameter ranges in afairly straightforward fashion. In addition,shield machines have been devised which arefitted with two or three overlapping cuttingwheels staggered one behind the other. In thisway, cross-sections which are not circular canbe driven. The installations in question arespecial forms of shield machines for specialpurposes.Apart from these machines being geared to acircular form and diameter, the length of thesections to be driven represents a furtherimportant feature especially for the economicapplication of a tunneling machine.The profile accuracy of the cavity cross-sectionis particularly high when tunnel machines areused. During heading, care should be taken toensure that the predetermined drivingtolerances are adhered to. Unscheduleddeviations from the axis can,in contrast to universal headings, by and largeonly be corrected with considerable difficulty.
II-4
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Universeller
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Universal
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XX
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XX
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1 Bauverfahren f
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Construction methods for mined tunnels
Querschnitts-
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Size of cross-
section
Querschnitts-
from
From of cross-
section
tunnel
Sicherung
Ausbau
Lining
Underground
water(U)
Merkmale des Tunnels/Features of tunnel
Umwelt/Environment
Grund(G)-
Schicht(S)-
Wasser
Groundwater(G)
Tunnell
nge
Length of
X X X
X X 0
X X
X X 0
X
_X X
X X X
X X X
X X X
X X X
SX SX 0
GX
GX
GX
s s ss
q
q s
s s
II-5
4. Tunneling machines TM
Tunneling machines (TM) either head theentire tunnel cross-section with a cutter head orcutting wheel full-face or in part segments bymeans of suitable extraction equipment.During the excavation phase, the machine ismoved forward either continuously or stroke-by-stroke.A difference is drawn between tunnel boringmachines TBM and shield machines SM.Tunnel boring machines remove the rock at theface, with the support generally being installedafterwards, following up at a distance.The machines are held in place during theexcavation phase by means of grippers pressedlaterally against the tunnel walls.Shield machines generally support the subsoilthat is being penetrated and the face by directmeans during the excavation phase. The shieldis advanced during excavation by jackingagainst the completed lining.A systematic compilation of tunneling ma-chines is provided in Fig. 2, which was basedon the classification contained in this section.
4.1. Tunnel Boring Machines (TBM)A distinction is drawn between tunnel boringmachines without shield body and those withone(Fig.3).
4.1.1. Tunnel boring machines withoutshieldsTunnel boring machines are employed in solidrock with medium to high face stability. Theydo not possess a completely closed shieldbody. Economic application can be stronglyinfluenced and restricted through high wearcosts of the cutting tools.Generally speaking, only a circular cross-section can be broken out by these machines.A rotating cutter head, which is equipped withroller bits (discs), possibly with tungstencarbide bits, is pressed against the face andremoves the rock through its notch effect. Inorder to provide the contact pressure at thecutter head, the machine is held radially bymeans of hydraulically moveable grippers.Extraction is gentle on the rock and results inan accurate profile.The machine occupies a large part of the cross-section. Systematic supporting is normallycarried out behind the machine (10 to 15 m andmore behind the face). In less stable and
particularly in friable rock, it must be ensuredthat the placing of support arches, laggingplates and anchors, in certain cases, evenshotcrete, is possible directly behind the cutterhead. It should be possible to carry outpreliminary investigations a n d rockstrengthening from the machine.In the case of bore diameters of > 10 m, so-called expansion machines can also be applied.Starting from a continuous pilot tunnel, theprofile is expanded in one or two workingphases using correspondingly designed cutterheads.During excavation at the face, small pieces ofrock, accompanied by an amount of dust, areproduced. As a consequence, devices forrestricting the dust development and dedustingare necessary for these machines:_ wetting with water at the cutter head_ dust shield behind the cutter head_ dust removal with dedusting on the back-upThe material transfer and supplies for themachine call for what, in some cases, can bevery long back-up facilities.
4.1.2. Tunnel boring machines with shieldsTBM-SIn solid rock with low stability or friable rock,tunnel boring machines are equipped with aclosed shield body. In this case, it is advisableto carry out supporting within the protection ofthe shield tail skin (segments, pipes, etc.),against which the machine supports itself. Thegripper system is then no longer needed.Otherwise, the explanations already providedfor tunnel boring machines also apply here.
4.2. Shield Machines SMA distinction is drawn between Shield Ma-chines with full-face extraction (cutter head)SM-V and shield machines with part extraction(milling boom, excavator)SM-T.Shield machines are employed in loose soilswith or without groundwater, in the case ofwhich generally the subsoil surrounding thecavity and the face have to be supported. Thecharacteristic feature of these machines is thetype of face support (Fig. 3).
4.2.1. Shield Machines with full-faceexcavation SM-V4.2.1.1 SM-V1 Face without supportIf the face is stable, e.g. in clayey soils, so-called open shields can be employed. The
II-6
cutter head equipped with tools removes thesoil; the loosened soil is carried away bymeans of conveyor belts or scraper chains.
4.2.1.2 SM-V2 Face with mechanical supportSupporting of the face is carried out via analmost closed cutter head. The plates arrangedbetween the spokes are elastically supported;they are pressed up against the face. Extractionis executed full-face via the cutter headequipped with tools; the loosened soil passesthrough slits, whose opening width is variable,between the spokes and the supporting plates,into the working chamber.The material is removed via conveyor belts,scraper chains or by hydraulic means.Scraper disc shields possess a high degree ofmechanization. Through the constant full-facecontact of the cutting wheel with the face, hightorque is required.In the case of types of soil, which tend to flow,supporting in the vicinity of the slits isincomplete, which can lead to settlements. It isextremely difficult to remove obstacles.
4.2.1.3 SM-V3 Face with compressed airapplicationIf groundwater is present, it has to be held backin the case of machines belonging to typesSM-V1 and SM-V2 unless it can be lowered.Either the whole tunnel is subjected tocompressed air or the machine is provided witha bulkhead so that only the working chamber isunder pressure. Airlocks are essential in bothcases.Particular attention must be paid to thecompressed air leakage via the shield tail sealand the lining.The support which is realized by theapplication of compressed air acts directly.Through suitable measures, it is also possibleto avoid an accumulation of compressed air,e.g. when sand lenses with water underpressure occur.
4.2.1.4 SM-V4 with fluid supportIn the case of these machines, the face issupported by a fluid that is under pressure.Depending on the permeability of the subsoilthat is present, effective fluids must be used forsupporting, whose density and/or viscosity canbe varied. Bentonite suspension has proved tobe particularly effective.The working chamber is closed to the tunnel
by a bulkhead. The pressure needed forsupporting the face can be regulated with greatprecision either by means of an air cushion orby controlling the speed of the delivery andfeed pumps. Supporting pressure calculationsare required.The soil is removed full-face by means of acutter head equipped with tools. Hydraulicconveyance with subsequent separation isessential.If it is necessary to enter the working chamber(tool change, repair work, removing obstacles),the fluid must be replaced by compressed air.The supporting fluid (bentonite, polymer) thenforms a slightly air-permeable membrane at theface, whose life span is restricted. Thismembrane facilitates the supporting of the facethrough compressed air and should be renewedif need be.When the machine is at a standstill,mechanical supporting of the face is possibleby means of segments, which can be shut, inthe cutting wheel or through plates that can beextended from the rear. These solutions areadvisable on account of the limited duration ofthe membrane.Stones or banks of rock can be reduced to asize convenient for conveyance through discson the cutting wheel and/or stone crushers inthe working chamber.
4.2.1.5 SM-V5 Earth pressure balance faceThe face is supported by earth slurry, which isformed from the material that has beenremoved. The shield's working chamber isclosed to the tunnel by means of a bulkhead.More or less closed cutting wheels equippedwith tools extract the soil. An extraction screwunder pressure carries the soil out of theworking area.The pressure is checked by loadcells, whichare distributed over the front side of thebulkhead. Mixing vanes on the rear of thecutting wheel and the bulkhead are intended toensure that the soil obtains a suitableconsistency.The supporting pressure is controlled throughthe thrust of the rams and the speed of theconveyor screw. The soil material in the screwor additional mechanical installations mustensure a seal in the extraction equipment, asotherwise the supporting pressure in theworking chamber cannot be retained due to theuncontrolled escape of water or soil.
II-7
Complete supporting of the face, especially inthe upper zone, only then succeeds providingthe supporting medium soil- can betransformed into a soft to stiff-plastic mass. Inthis connection, the percentile share of the finegrain smaller than 0.6 mm has a considerableinfluence.In order to extend the range of application ofshield machines with earth pressure balancesupport, suitable agents for conditioning thesoil material can be applied: bentonite,polymer, foam from polymers. In such cases,the environmental compatibility of the materialfor landfill purposes must be taken intoconsideration.
4.2.2. Shield machines with partial axeexcavation SM-T4.2.2.1 SM-T1 Face without supportIf the face is perpendicular or stable with asteep slope, it is possible to use this type ofshield. The machine merely comprises theshield body and the extraction tool (excavator,milling boom or scarifier). The soil is removedvia conveyor belts or scraper conveyors.
4.2.2.2 SM-T2 Face with partial supportThe face can be supported by platforms and/orbreasting plates.In the case of platform shields, the frontsection is divided up by one or a number ofplatforms on which slope form, which supportthe face. The soil is removed manually or bymechanical means.Platform shields possess a low degree ofmechanization. Disadvantageous is the dangerof major settlements resulting from un-controlled face support.
II-8
TBM ohne schild TBMTBMTBM without Shield
TunnelbohrmaschinenTBMTunnel Boring Machines
TBM mit SchildTBM-S TBM-STBM with Shield
Ortsbrust ohne Stützung SM-V1Face without support
Ortsbrusut mitTunnelvortriebs- mechanischer Stützung SM-V2maschinen Face with mechanicalTVM support
TunnellingMachines Schildmaschinen Ortsbrust mit Druckluft-
mit Vollschnittabbau Beaufschlagung SM-V3SM-V Face with compressedShield Machines with air applicationfull-face
Ortsbrust mit Flüssig-Keitsstützung SM-V4Face with fluid support
Ortsbrust mit Erddruck-Schildmaschinen Stützung SM-V5SM Face with earth pressureShielded Machines balance support
Ortsbrust ohne Stützung SM-T1Face without support
Ortsbrust mit Teilstützung SM-T2Schildmaschinen mit Face with purtial supportteiltlächigem AbbauSM-T Ortsbrust mit Druckluft-Shield Machines with Beaufschlagung SM-T3part heading Face with compressed
air application
Ortsbrust mit Flüssigkeits-Stützung SM-T4Face with fluid support
Sonderformen und Kombinationen siehe Textteil / Special forms and combinations are provided in the text
2 Übersicht Tunnelvortriebsmaschinen(TVM).Sonderformen und Kombinationen sind in Text beschrieben Survey of tunnelling machines(TM). Special forms and combinations are described in the article
II-9
In the case of shield machines with breastingplates, the face is supported through breastingplates, which are mounted on hydrauliccylinders. The breasting plates are partiallyretracted for removing the soil manually or bymechanical means.A combination of breasting plates andplatforms is possible. If supporting of the roofarea is sufficient, extensible breasting platescan be used there.
4.2.2.3 SM-T3 Face with compressed airapplicationIf groundwater is present, this must be held incheck in the case of machines of the type SM-T1 and SM-T2. The tunnel is then set undercompressed air or the machines are providedwith a bulkhead. The material is removedhydraulically or dry via a material lock.
4.2.2.4 SM-T4 Face with fluid supportIn the case of this shield type, the workingchamber is also closed by a bulkhead. It isfilled with a fluid, whose pressure is regulatedvia the speed of the delivery and feed pumps.The soil is removed via a cutter, which, insimilar fashion to suction dredgers, also takesaway the fluid-soil mixture.
4.3. Adaptable dual purpose shieldmachines
A large number of tunnels pass throughstrongly varying subsoil conditions, which canrange from rock to loosely bedded soil. As aresult, tunneling methods have to be geared tothe geotechnical prerequisites and shieldmachines, which are correspondinglyadaptable, employed.a) Shield machines, in the case of which theextraction method can be changed withoutmodification:_ earth pressure balance shield SM-V5 _
compressed air shield SM-V3_ fluid shield SM-V4 _ compressed air shield
SM-V3b) Shield machines, in the case of which theextraction method can be changed throughmodification. Findings are available with thefollowing combinations:_ fluid shield SM-V4 _ shield without support
SM-V1_ fluid shield SM-V4 _ earth pressure balance
shield SM-V5_ earth pressure balance shield SM-V5 _ shield
without support SM-V1_ fluid shield SM-V4_ TBM-S
4.4. Special forms4.4.1. Finger shieldsThe shield body is split up into fingers, whichcan be extended individually. The soil isremoved via roadheaders, cutting wheels orexcavators. An advantage of finger shields isthat they deviate from the circular form ande.g. can also excavate horse-shoe profiles. Inthe latter case, the base is usually open. Theforepoling is also used.
4.4.2. Shields with multi-circular cross-sectionsThese shield types represent the latest state ofdevelopment for fully mechanized headings. Inthe case of these machines, the staggeredcutting wheels are designed to overlap.
4.4.3. Articulated shieldsPractically all-existing shields can be providedwith an articulating joint. If the ratio of theshield body length to the shield diameterexceeds the value l, generally a joint isincorporated in order to improve the steability.The arrangement can also be necessary ifextremely tight curve radii are to be driven.
4.4.4. Cowl shieldThe shield cutting edge is tapered toapproximate the natural angle of slope of thesoil. When tunneling under compressed air,this means that safety against blowout isenhanced.
4.4.5. Displacement shieldOnly suitable for soft-plastic soils. Themachine has no extraction tool. It is pressedinto the soil, which results in this beingpartially displaced and partially removedthrough an aperture in the bulkhead.
4.4.6. Telescopic ShieldsIn order to arrive at higher rates of advance,telescopic shields have been designed.Essentially, the objective is to install the liningduring the removal of the soil.
II-10
4.5. Supporting and liningAs far as the process techniques referred to inthese recommendations are concerned, thetunneling machine together with the supportand/or lining represent a single unit in terms ofprocess technology.
4.5.1. Tunnel boring machines TBMDue to the excavation procedure which isgentle on the rock and the advantageouscircular form, the extent of the necessarysupporting measures is usually less than forexample for drill + blast. In less stable rock,the exposed areas have to be supported quicklyin order to restrict any disaggregation of therock and thus retain the rock quality as far aspossible.Should breaks occur in the vicinity of thecutter head, the extent of the necessarysupporting measures can increase considerably.
4.5.1.1 Rock boltsRock bolts are generally arranged radially inthe cross-sectional profile of the tunnel, a rockmatrix-oriented set-up enhance the effect of theshear dowels. Installed locally, they prevent theflaking or detaching of rock plates, arrangedsystematically, they prevent loosening of theexposed tunnel sidewall. Rock bolts areespecially suitable for subsequently increasingthe lining strength, as they can still be installedat a later stage.The anchors are installed in the vicinity of theworking platform behind the machine or inspecial cases, directly behind the cutter head.
4.5.1.2 ShotcreteShotcrete serves to seal the exposed rocksurface either partially or completely (thick-ness 3 to 5 cm) or provide it with a supportinglayer (thickness 10 to 25 cm, in exceptionalcases, even more). In order to enhance theloadbearing capacity of the shotcrete lining, itis provided with a single-layer (on The rockside) or two-layers (rock and exposed side) ofmesh reinforcement. Alternatively, steel fibbershotcrete can be applied. The shotcrete isgenerally installed in the vicinity of theworking platform behind the machine.4.5.1.3 Support archesSupport arches serve to effectively support therock directly after the excavation and to protectthe working area. As a consequence, they are,first and foremost, applied in friable and
unstable, squeezing rock. Rolled steel sectionsor lattice girders are used as support arches.Support arches are normally installed directlybehind the cutter head in sections in the roofzone or as a closed ring.
4.5.2. Tunnel boring machines with shieldTBM-S and shield machines SMIn the case of tunnel boring machines withshield or shield machines, the support isinstalled within the protection of the shield tail.This usually consists of prefabricatedsegments.Apart from supporting the surrounding subsoil,it serves in the case of most machines of thistype as the abutment for the thrust rams.The load transfer between the lining and thesubsoil is created by grouting the annular voidat the shield tail as continuously as possible.This does not apply to lining systems, whichare directly pressed against the subsoil.In general, it must be ascertained whether alining comprising an inner shell made ofreinforced or un-reinforced concrete is needed.Segments and pipes are normally utilised assingle skin linings.
4.5.2.1 Concrete and reinforced concretesegmentsThe customary precast elements are concreteor reinforced concrete segments. Alone thestresses caused by transport and installationmakes it necessary for the segments to bereinforced. Segments with steel fibberreinforcement have also been designed in orderto strengthen the edges and corners, whichcannot be reinforced by rods, through steelfibbers.
4.5.2.2 Cast steel and steel segmentsThrough the development of castingtechnology, segments today can be suppliedmade of cast steel, e.g. with the materialdesignation GGG 50, with low overallthickness, sufficient dimensional accuracy andsufficient elasticity.In exceptional cases, as e.g. extremely narrowcurves and in the vicinity of apertures in thelining, welded steel segments can represent atechnical solution for overcoming load con-contortions on the lining.
4.5.2.3 Liner plates
II-11
Pre-formed steel plates in the form of linerplates can represent an economic solution as afull surface provisional support in extremelyfriable rock.
4.5.2.4 Extruded concreteExtruded concrete is a tunnel lining, which isinstalled, in a continuous workingprocess as an unreinforced or steel-fibrereinforced concrete support behind thetunneling machine between the shield tail anda mobile inner form. Thus, the extrudedconcrete in its fresh state already supports thesurrounding rock, also in groundwater. Anelastically supported stop-end formwork,which is pushed forwards concrete pressure,assures a constant support pressure in theliquid concrete.
4.5.2.5 Timber laggingIn non-water bearing soil, the primary supportcan comprise a wooden or reinforced concreteslatted construction, which is installed betweensteel profiles (ribs and lagging), which isassembled protected by the shield tail. Whenthe shield tail releases the steel ribs, they and,in turn, the lagging, are pressed against the soilusing hydraulic jacks. The tunneling machinecan be advanced by thrusting against this pre-stressed construction.
4.5.2.6 PipesPipe-jacking represents a special method, inthe case of which reinforced concrete or steelpipes are thrust forward from a jacking stationto serve as a support and/or final lining.For certain construction projects, rectangularcross-sections are also employed with thejacking method.
4.5.2.7 Reinforced ConcreteReinforced concrete is only used n conjunctionwith blade shields. In the same way asshotcrete, reinforced shotcrete can be appliedin conjunction with tunneling machines forsupporting purposes when they do not transferthe thrusting forces onto the lining. Thereinforced concrete is produced in 2.50 to 4.50m wide sections protected by so-called trailingblades, which are supported on the lastconcreted section by conventional means withmobile formwork.
5 . Relationship between geotechnics
and tunneling machines
5.1. Ranges of application for tunnelingmachines
The individual tunneling machines are suitablefor certain geotechnical and hydro-geographical ranges of application in con-junction with their process-related andtechnical features.The specific types of machines are related totheir main ranges of application in Fig.4 withgeo-technical terms and parameters as thebasis. In addition, it is shown there just how faran extension of the range of application ispossible should this present itself as a result ofsimplified methods, in order to increase theeconomy or with regard to the heterogeneity ofthe subsoil that is present.As one of the most essential influencingfactors for the application is the lack orpresence of groundwater, the fields ofapplication are divided into subsoil with orwithout groundwater.Extremely varied extraction tools can be usedfor removing the subsoil that is present. Theyare listed in accordance with their suitabilityfor the geotechnical ranges of application andthe machine types.The forms of supporting and lining suit ablefor the individual machines are presentedunder 4.5. As a result, they have not been listedseparately in a table.
II-12
3. Systeme der Tunnelvortriebsmaschinen
Tunneling machine systems
5.2. Important selection and evaluationcriteria
TBMThe main range of application is in stable tofriable rock, in the case of which undergroundand fissure water inbursts can be mastered. Theuni-axial compressive strength should amountroughly to between 300 and 50 [MN/m2].Higher strengths, toughness of the rock and ahigh proportion of abrasion resistant mineralsrepresent economic limits for -
application (abrasiveness according to Cerchar,Schimanek, et al). A restriction of the gripperforce of the TBM can also place its applicationin question.To assess the rock, the cleavage strength _z
≈25 to 5 [MN/m2] and the RQD value arerequired. Given a degree of decomposition ofthe rock with RQD of 100 to 50 [%] and afissure spacing of > 0.6 m the application of aTBM appears assured.Should the decomposition be higher, thestability has to be checked.
TBM-SThe main field of application is in friable tounstable rock, also with inbursts ofunderground and fissure water. The bondingstrength is greatly reduced given possibly thesame rock strength in stable rock. Thiscorresponds to a fissure gap of ≈ 0.6 to 0.06[m] and a RQD value between approx. 50 and10 [%]. Generally, however, an application ofthe TBM-S is possible given lower rockcompressive strength _D between approx. 50and 5[MN/m2] and correspondingly lesscleavage strength of _z between approx. 5 and0.5 [MN/m2].
SM-V1This type of machine is mainly used in over-consolidated and thus dry, stable clay soils. Inorder to make sure that no harmful surfacesettlements occur even given thin overburdens,the compressive strengths _D of the materialshould not be less than approx. 1.0 [MN/m2].The cohesion cu accordingly registers valuesabove approx. 30 [kN/m2].Only in rock which is relatively immune tooverbreak can underground and fissure wateringress be coped with.
SM-V2On account of the full-face supporting cutterhead, easily removed, largely dry types of soilcan be mastered, first and foremost non-stablecohesive soils or interstratifications comprisingcohesive and non-cohesive soils. Majorintercalation such as boulders is extremelydifficult to cope with.The cohesion cu of these soils amounts tobetween 30 and 5 [kN/m2]. The grain size isrestricted upwards due to the slit width in thecutter head. In order to ensure that surfacesettlements are kept to a minimum, the slit
II-13
width and contact pressure have to beoptimized.
SM-V3This machine under compressed air working ismainly used when types SM-V1 and SM-V2have to operate in groundwater. Its mainapplication must be regarded as in soils withinterstratification. The air permeability of therock and the air consumption and the relatedblow -out danger are the governing criteria forthe application of this type of machine.
SM-V4Its main range of application is tunneling innon-cohesive types of soil with or withoutgroundwater.During the excavation process, a fluid underpressure e.g. bentonite suspension supports theface. Layers of gravel and sand are the typicalsubsoil. Coarse gravel can in certain casesprevent membrane formation. In the event ofhigh permeability, the supporting fluid must beadapted to suit. Major stratification, whichcannot be pumped, is reduced in advancecrushers. The proportions of ultra-fine grain <0.02 mm should amount to ≈ 10%. Higherquantities of ultra-fine material can lead todifficulties during separation.
SM-V5Types of machines with earth pressure balancesupporting are especially suitable for withcohesive fractions. In this case, the proportionof ultra-fine grains < 0.06 mm should amountto at least 30 %. In order to produce the desiredearth slurry, groundwater has to be present orwater must be added. The necessaryconsistency of the spoil can be improvedthrough the addition of suitable conditioningagents such as bentonite or polymer. In thisway too, the danger of sticking is considerablyreduced.
SM-T1This type of machine can be used providing theface is thoroughly stable. Refer also to SM-T1.
SM-T2This type of machine can be used when thesupport due to the material lying on theplatforms at a natural sloping angle suffices fora conditional control of deformations duringtunnel advance. Breastplates can be used for
supporting purposes in the roof and platformzone. Slightly to non-cohesive clay-sand soilswith a corresponding angle of friction are themain range of application.
SM-T3The application of this type of machine isgiven when types SM-T1 and SM-T2 are to beused in groundwater. Either the entire workingarea, including the excavated tunnel or solelythe working chamber is subjected tocompressed air.
SM-T4When clay-sand mixtures are to be removedunder water, this type of machine is used. Therequirements concerning the groundcorrespond to type SM-T4. Obstacles can becleared using the cutting boom. Supportingplates are arranged in the roof zone.
II-1
4
σ σ
≥ ≥≥
Baugrund
Geo-
subsoil
standfest
nachbr
chig
bindig
bindig
Wechsellagerung
nicht bindig
technische
bis nachbr
chig
bis gebr
ch
standfest
nicht standfest
kennwerte
competent to
caving in to
cohesive
cohesive
mixed
non-cohesive
Geotechinical Parameters
caving in
unstable
stable
not stable
conditions
Gesteinsfestigkeit
D[MN/ ‡u]
Rock Compressive strength
Zugfestigkeit
z[MNl ‡u]
Tensile strength
RQD-Wert
RQD[%]
RQD value
Kluftabstand
[m]
Fissure spacing
Koh
sion
Cu[kNl ‡
u]Cohesion
Kornverteilung
<0,02[%]
30
30
10
Grain distribution
<0,06[5]
30
30
TBM
0.W.
TBM
m.W.
TBM-S mit Schild
o.W.
TBM-S with shield
m.W.
SM-V1 ohne St
zung
o.W.
SM-V1 without support m.W.
SM-V2 mechan.St
zungo.W.
SM-V2 mech.support
m.W.
SM-V3 mit Druckluft
o.W.
SM-V3 with compressed air
m.W.
SM-V4 Fl
ssigkeitsst
tzung
o.W.
SM-V4 fluid support
m.W.
SM-V5 Erddruck-St
tzung
o.W.
SM-v5 earth pressure
balance support
m.W.
SM-T1 ohne St
tzung
o.W.
SM-T1 without supportm.W.
SM-T2 Teilst
zung
o.W.
SM-T2 partial su
m.W.
SM-T3 mit Druckluft
o.W.
SM-T3 with compressed air
m.W.
SM-T4 Fl
ssigkeitsst
tzung
o.W.
SM-T4 fluid support
m.W.
Abbauwerkzeug
Vrollend
rollend
sch
lend
sch
lend
lsend/sch
lend
lsend
Extracion tool
(Diskenmei§el)
(Diskenmei§el)
(Flachmei§el)
(Flachmei§el)(Stichel/Flachmei§el)(Stichel)
rolling
rolling
stripping
stripping
loosening/strippingloosening
(cutter disc)
(disc bit)
(flat bit)
(chisel)
(cutter/flat bit)
(pick)
Tritzend
ritzend
ritzend
sch
lend
sch
lend
lsend
(Spitzmei§el)
(Spitzmei§el)
(Spitzmei§el)
(Flachmei§el)
(Flachmei§el)
(Stichel)
notching
notching
notching
stripping
stripping
loosening
(pick)
(point bit)
(point bit)
(flat bit)
(flat bit)
(pick)
o.W.=ohne Grund-bzw.Schichtwasser/
without groundwater or underground water
Haupteinsatzbereich
/Main field of appl
m.W.=mit Grund-bzw.Schichtwasser/
with groundwater or underground water
Einsatz m
glich/
application possible
4 Einsatzbereich der Tunnelvortriebsmaschinen
Ranges of application for tunnelling machines
100 bis 50
>2,0 bis 0,6
50 bis 10
0,6 bis 0,06
30
30 bis 5
30 bis 5
1,0
25 bis 5
Fels/Festgestein/
Hard rock/soil
Boden/Lockergestein/
Soft rock/soil
0,1
50 bis 5
5 bis 0,5
300 bis 50
II-15
5.3. Pointers for special geotechnical andconstructional conditions
Due to special marginal conditions, theapplication of a certain method and/or atunneling machine can be considerablyrestricted. By use of suitable measures,however, an application can be made possible,above all, providing these special conditionsonly occur locally or over a limited zone. Thedecisive factor is then the economic feasibility.Through lowering the groundwater, asimplified technique for the tunnelingmachines can be applied, which e.g. facilitatesthe removal of obstacles, should these beexpected at very frequent intervals.In the case of strongly fluctuating geotechnicalconditions, the possibility of being in aposition to adapt the operating mode of thetunneling machine brings advantages. This is,above all, purposeful when lengthy inter-connected sections are concerned (see 4.3).When selecting the suitable tunneling ma-chines, a critical evaluation of eventualadditional equipment is advisable, which maybe required to cope with any deviations fromthe projected geotechnical conditions within acertain range.By means of grouting, freezing, vibratorcompaction or soil replacement, the subsoilcan be improved. This is suitable for the entiretunnel cross-section but most importantly forthe area above the tunnel when only thinoverburden is present.Using compressed air when a thin overburdenis present, e.g. below a watercourse, ballast ora waterproofing and ballasting layer should beinstalled.When fluid support is used, additionalmeasures are required in order to avoiduncontrollable suspension losses given highpermeability of the soil and thin overburden.Should there be a high frequency of coarsegravels and boulders in the sand, the utilizationof a rock crusher enhances the operationalsafety in the case of fluid supported shieldmachines in addition to equipping the cutterhead with cutter discs.A tunneling machine is only in the position tohead a circular cross-section, which has aconstant diameter. However, it is technicallypossible to expand the driven circular cross-section over short stretches subsequently insuch a way that other, above all larger cross-sectional forms are created, e.g. for a
subterranean station, employing soilimprovements should these be called for.The greater the proportion of ultra finematerial in the subsoil, the more attention hasto be paid to spoil separation in the case offluid supported shield machines.The requirements on the water content and/orthe degree of purity of the separated soilmaterial then govern the limits of the economyof the method.The operational safety of a method is, amongother things, dependent on a tunnel’s over-burden. This should generally correspond atleast to the diameter of the tunnel excavated, ifadditional measures are to be avoided. Thismust be accorded special attention in the caseof large diameters.The unrestricted application of certain types ofmachine is not always assured as the diameterincreases and is only possible in conjunctionwith suitable measures. In the case of tunnelboring machines with large diameters,machines with shield body and systematicplacing of segments have proved themselves.As far as earth pressure balance shieldmachines are concerned, extremely hightorques at the cutter head are necessary, whichpossibly cannot be attained in the case of verylarge diameters.As far as earth pressure balance shieldmachines are concerned, cutter discs can beemployed for reducing coarse gravel andboulders. The dimensions of the screwconveyor must be designed in such a fashionthe coarse lumps which are present afterextraction can be removed. A screw without ashaft is suitable for conveying coarse lumps.Certain clays or rocks containing clay cancause the cutter head to stick and to formbridges over apertures for removing material.This phenomenon can be counteracted throughthe proper shape, flushing installations oradditives, which reduce the stickiness.Ingresses of gas require flameproof protectionfor the tunneling machines or a change ofoperational mode.
Italy
ITA WORKING GROUP No. 14(ITA WG14)
“MÉCANISATION DE L’EXCAVATION”“MECHANIZATION OF EXCAVATION”
Tuteur/Tutor Animateur Vice-AnimateurS.KUWAHARA N.MITSUTA M.DIETZ
PRÉPARATION DU RAPPORT “RECOMMANDATIONSPOUR LE CHOIX DES MACHINES FOREUSES”
PREPARATION OF THE REPORT “GUIDELINES FOR THESELECTION OF TBM’S”
(Contribution from the Italian Tunneling Association“Mechanized Tunneling”working group - GL14, to the ITA
WG14)
World Tunnel Congress‘98Tunnel and Metropolis
24th ITA Annual Meeting25 - 30 April 1998Sao Paulo - Brazil
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CONTENTS
1. Aim and Scope (deleted)........................................................................................................................12. Classification and Outline of Tunnel Excavation Machines .............................................................1
2.1. Classification of tunnel excavation machines.............................................................................12.2. Rock tunneling machines ..............................................................................................................3
2.2.1. Unshielded TBMs..................................................................................................................32.2.2. Special Unshielded TBMs....................................................................................................32.2.3. Single Shielded TBMs: SS-TBMs ......................................................................................32.2.4. Double Shielded TBMs: DS-TBMs....................................................................................4
2.3. Soft Ground Tunneling Machines ................................................................................................42.3.1. Open Shields ..........................................................................................................................42.3.2. Mechanically Supported Closed Shields............................................................................42.3.3. Mechanical Supported Open Shields..................................................................................52.3.4. Compressed Air Closed Shields ..........................................................................................52.3.5. Compressed Air Open Shields.............................................................................................52.3.6. Slurry shields..........................................................................................................................52.3.7. Open slurry shields................................................................................................................62.3.8. Earth Pressure Balance Shields – EPBS ............................................................................62.3.9. Combined Shields: Mixshield, Polyshield.........................................................................7
3. Conditions for Tunnel Construction and Selection of TBM Tunneling Method ...........................73.1. Investigations ..................................................................................................................................7
3.1.1. Introduction ............................................................................................................................73.1.2. Parameter selection..............................................................................................................123.1.3. Monitoring during construction.........................................................................................243.1.4. TBM tunneling monitoring system...................................................................................24
4. REFERENCES......................................................................................................................................28
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1. Aim and Scope (deleted)
2. Classification and Outline ofTunnel Excavation Machines
2.1. Classification of tunnel excavationmachines
All over the world there are differentclassification schemes for tunnel excavationmachines (TMs), based on differentclassification purposes.
The proposed classificat ion schemerepresented in fig. l is based on the possibilityof dividing TMs on the basis of_
_ ground support system_ excavation (method and tools)_ reaction force tool
Following the two machine categories intowhich all TMs may be grouped, the nextparagraphs broadly illustrate all types of TMs.
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2.2. Rock tunneling machines
2.2.1. Unshielded TBMs
Function principle – A cutterhead, rotating onan axis which coincides with the axis of thetunnel being excavated, is pressed against theexcavation face; the cutters (normally disccutters) penetrate into the rock, pulverizing itlocally and creating intense tensile and shearstresses. As the resistance under each disccutter is overcome, cracks are created whichintersect creating chips. Special buckets in thecutterhead allow the debris to be collected andremoved to the primary mucking system. Theworking cycle is discontinuous and includes:1) excavation for a length equivalent to theeffective stroke; 2) regripping; 3) new -excavation.Main components of the machine - The TBMbasically consists of:_the traveling element which basically consists
of the rotating cutting head and the primarymucking system_
_a stationary element which counters the thrustjacks of the cutterhead using one or morepairs of grippers which anchor the TBMagainst the tunnel walls_
_a rear portion containing the driving gear andback-up elements;
Depending on the type of stationary element itis possible to divide unshielded TBMs into:main beam types or kelly types.Main field of application - Rock masses whosecharacteristic range from optimal to moderatewith medium to high self-supporting time.
2.2.2. Special Unshielded TBMs
2.2.2.1 Reaming Boring Machines - RBMsFunction principle - The Boring Machine is aTM which allows a tunnel made using a TBM(pilot tunnel) to be widened (reaming).The function principle on which it is based isidentical to that for the unshielded TBM; theworking stages are also the same as for theunshielded TBM.Main components of the machine - The RBM
basically consists of:_the traveling element which basically consists
of the reaming head, on which the cuttingtools are fitted_and the primary muckingsystem_
_a stationary element located inside the pilottunnel opposite the reaming head, whichcounters the thrust jacks on the cutting headusing two pairs of grippers;
_a rear portion containing the engines_thedriving gear and back-up elements.
A special type of RBM is the Down ReamingBoring Machine_this machine is used for shaftexcavation and enables the top-to-bottomreaming of a pilot tunnel dug using a RaiseBorer_see below_.Main field of application - Rock masses whosecharacteristics range from optimal to moderatewith medium to high self-supporting time.
2.2.2.2 Raise BorerFunction principle - The Raise Borer is amachine used for shaft excavation whichenables the top-to-bottom reaming of a smalldiameter pilot tunnel created using a drillingrig.A cutterhead, rotating on an axis, whichcoincides, with the axis of the tunnel beingexcavated, is pulled against the excavation faceby a drilling rod guided through the pilottunnel. The cutters provoke crack formationusing the same mechanism illustrated for theunshielded TBMs. Debris falls to the bottom ofthe shaft where it is collected and removed.Main components of the machine - The RaiseBorer basically consists of 3 parts:_ the cutterhead (discs or pin discs);_ the drilling rod which provides torque and
pull to the cutterhead;_ a body, housed outside the shaft, which gives
the drilling rod the necessary torque and pullfor excavation.
Main field of an application - Rock masseswith optimal to poor characteristics.
2.2.3. Single Shielded TBMs: SS-TBMsFunction principle -See the section forunshielded TBMs. Inthis case the workingcycle is also -
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discontinuous and includes:l) excavation for a length equivalent to theeffective stroke; 2) regripping (using thelongitudinal thrust jacks braced against theprecast segments of the tunnel lining) andsimultaneous laying of tunnel lining usingprecast segments; 3) new excavation.Main components of the machine_the cutterhead (discs), which can be
connected rigidly to the shield or articulated;_ the protective shield which is cylindrical or
slightly truncated cone-shaped and containsthe main components of the machine; theshield may be monolithic (the machine isguided by the thrust system and/-or cutterhead) or articulated (the machine isguided by the thrust
system and/or shield articulation);_ the thrust system which consists of a series
of longitudinal/hydraulic jacks placed insidethe shield which are braced against thetunnel lining.
Main field of application - Rock masses whosecharacteristics vary from moderate to poor.
2.2.4. Double Shielded TBMs: DS-
TBMs
Function principle -Similar to unshieldedTBMs, but offers thepossibility of a -continuous work cycle
owing to the double thrust system, making itmore versatile since it can move forward evenwithout laying the tunnel lining of precast -segments.Main components of the machine:_ the cutterhead (discs);_ the protective shield which is cylindrical or
slightly truncated cone-shaped and -articulated, and contains the main machinecomponent;
_ the double thrust system which consists of: 1) a series of longitudinal jacks; 2) a series of grippers, positioned inside the
front part of the shield which use thetunnel walls to brace against the thrustjacks.
Main field of application - Rock masses whosecharacteristics range from excellent to poor.
2.3. Soft Ground Tunneling Machines
2.3.1. Open
ShieldsFunction principle -The open shield is aTM in which face
excavation is -accomplished using a partial sectioncutterhead.At the base of the excavating head are handshields and partly mechanized shields in whichexcavation is accomplished using a roadheaderor using a bucket attached to the shield, andusing an automatic unloading and muckingsystem.
Main components of the machine_ the face excavation system;_ the protective shield whose shape can be
altered to suit the type of section to beexcavated (non-obligatory circular section);
_ the thrust system consisting of longitudinaljacks.
Main field of application - Rock masses whosecharacteristics vary from poor to very bad, -cohesive or self-supporting ground in general.It can also be used in ground, which lacks self-supporting capacity using appropriatepreconsolidation or presupport of the -excavation face.
2.3.2. Mechanically Supported Closed
Shields
Function principle -This mechanicallysupported, closedshield is a TBM inwhich the cutterheadplays the dual role of
acting as the cutterhead and supporting theface using mobile plates, integral to thecutterhead, thrust against the face by specialhydraulic jacks. The debris is extractedthrough adjustable openings or buckets andconveyed to the primary mucking system.Main components of the machine_ the cutterhead (blades and teeth);_ the protective cylindrical shield containing
all the main components of the machine;_ longitudinal thrust jacks.Main field of application - Soft rocks, cohesiveor partially cohesive ground, self-supportingground in general. Absence of groundwater.
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2.3.3. Mechanical Supported Open
Shields
Function principle -Similar to that -described for open -Shields; face stability isachieved using metal
plates which thrust alternatively against theface.Main components of the machine - Similar tothose described for open shields; the metal facesupport plates are located in the upper part ofthe section and are integral to the shield.Main field of an application - Soft rocks,cohesive or partially cohesive ground, self-supporting ground in general. Absence ofgroundwater.
2.3.4. Compressed Air Closed Shields
Function principal - Incompressed air closedshields the rotating -cutterhead acts as themeans of excavation
whereas face support is ensured by compressedair at a sufficient level to balance the -hydrostatic pressure of the ground. Debris isextracted from the pressurized excavationchamber using a ball valve-type rotary hopperand then conveyed to the primary muckingsystem.
Main components of the machine_ the cutterhead (blades and teeth);
_ the protective cylindrical shield containingall the main components of the machine; thefront part is closed by a bulk head, whichguarantees the separation between theexcavation chamber (pressurized), housingthe cutterhead, and the zone containing themachine components (unpressurized);
_ longitudinal thrust jacks.Main field of application - Ground lackingself-supporting capacity and with medium-lowpermeability (k ≤ 10 –4m/s). Presence of -groundwater. Higher permeability can belocally reduced by injecting bentonite slurryonto the excavation face. The operating limit ofthe machine is the maximum pressureapplicable based on regulations for the use ofcompressed air in force in different countries.
2.3.5. Compressed Air Open Shields
Function principle - Asin the case of openshields, face -excavation is achievedusing a roadheader;face support is -
provided by compressed air in sufficientquantities to balance the hydrostatic pressureof the ground.Main components of the machine_face excavation system ( roadheader,
excavator);_ protective shield shaped to fit the type of
section to be excavated; the front part, whichhouses the roadheader, is closed by abulkhead separating the shield and -excavation chamber (pressurized);
_ longitudinal thrust jacks.Main field of application - The same as forcompressed air closed shields.
2.3.6. Slurry shields
2.3.6.1.Slurry shields-SS
Function principle - The cutterhead acts as themeans of -excavation whereasface support is -provided by slurry
counterpressure,namely a suspension of bentonite or a clay andwater mix (slurry).This suspension is pumped into the excavationchamber where it reaches the face andpenetrates into the ground forming the filtercake, or the impermeable bulkhead (fineground) or impregnated zone (coarse ground)which guarantees the transfer of -couneterpressure to the excavation face.Excavated debris by the tools on the rotatingcutterhead consists partly of natural soil andpartly of the bentonite or clay and watermixture (slurry). This mixture is pumped(hydraulic mucking) from the excavationchamber to a separation plant (which enablesthe bentonite/clay slurry to be recycled)normally located on the surface.Main components of the machine_ cutterhead (discs, blades or teeth);_ protective shield containing all the main
components of the machine; the front part is
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sealed by a bulkhead which guarantees theseparation between the shield and the
excavation chamber (pressurized) containingthe cutterhead;
_ longitudinal thrust jacks;_ mud and debris separation system (normally
located on the surface).Main field of application - Ground with limitedself-supporting capacity. In granulometric -terms, slurry shields are mainly suitable forexcavation in sand and gravels with silts. Theinstallation of a crusher in the excavationchamber allows any lumps, which would notpass through the hydraulic mucking system tobe crushed. The use of disc cutters enables themachine to excavate in rock. Polymers can beused to excavate ground containing much siltand clay. Presence of groundwater.
2.3.6.2 Hydroshields HS
Function principle -Identical to that -described for -uncompensated slurryshields; the only -
difference is the way of transferring thecounterpressure to the face.In the closed slurry shield in which thecounterpressure is compensated inside theexcavation chamber, in addition to the rotatinghead, there is always a metal buffer whichcreates a chamber partially filled with airconnected to a compressor which can adjustthe counterpressure at the face independent ofthe hydraulic circuit (supply of bentonite slurryand mucking of slurry and natural ground)
Main components of the machine - Similar tothose described for closed slurry shields withuncompensated counterpressure.
2.3.7. Open slurry shields
Function principle -It is identical to thatdescribed for -compressed air openshields. In this case face
support is provided by slurry counterpressure.Depending on the function of the cutterheadused, the following types can be identified:
Thixshield: excavation using a roadheaderHydrojetshield: excavation using high-pressurewater jetsMain components of the machine – Similar tothose described for compressed air openshields.Main field of application - Similar to thatdescribed for the closed slurry shield.
2.3.8. Earth Pressure Balance Shields
– EPBS
2.3.8.1 Earth Pressure Balance Shields -EPBS.
Function principle - Thecutterhead serves as themeans of excavationwhereas face support isprovided by the -
excavated earth which is kept under pressureinside the excavation chamber by the thrustjacks on the shield (which transfer the pressureto the separation bulkhead between the shieldand the excavation chamber, and hence to theexcavated earth).Excavation debris is removed from theexcavation chamber by a screw conveyorwhich allows the gradual reduction of pressure.Main components of the machine_ cutterhead: rotates with cutting spokes;_ protective shield similar to that used for
closed slurry shields;_ thrust system: longitudinal jacks which brace
against the lining of precast segments.Main field of application - Ground with limitedor no self-supporting capacity. In -granulometric terms, earth pressure balanceshields are mainly used for excavating in siltsor clays with sand. The use of additives, suchas high-density mud or foams, enablesexcavations in sandy-gravely soil.
2.3.8.2 .Special EPBSDK shield - Differs from the earth pressurebalance shield because of the geometry of thecutterhead whose central cutter projects furtherthan the cutters on the spokes, thus creating aconcave cavity.Double shield (DOT shield) - These are twopartially interpenetrated earth pressure balanceshields which operate simultaneously on thesame plane, creating a “binocular” tunnel.Flexible Section Shield Tunneling Method -
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Earth pressure balance shield in which theexcavation system is based on the presence ofseveral rotating cutterheads which enable theconstruction of non-cylindrical sections.Elliptical Excavation Face Shield Method -Earth pressure balance shield in which thecombined action of a circular cutterhead andadditional cutters enables an elliptical sectionto be excavated.
Triple Circular Face Shield Tunnel - Thisconsists of three shields, operating using earthor slurry pressure balance, which allow largeexcavation sections to be constructed, such asthose required to house an undergroundrailway station.Vertical Horizontal Continuous Tunnel - Thisis a slurry pressure balance TM consisting of amain shield, for shaft excavation, whichcontains a spherical joint housing a secondaryshield.When the main shield has reached theappropriate depth, the spherical joint is rotated90_ and the secondary shield starts tunnelexcavation.Horizontal Sharp Edge Curving Tunnel -Similar to the Vertical-Horizontal ContinuousTunnel, it enables the construction of twotunnels intersecting at right angles.Double Tube Shield Technology - This is a TMfitted with two concentric shields. The mainshield excavates the tunnel with the largesection; the secondary shield then excavatesthe tunnel with the smaller section.
2.3.9. Combined Shields: Mixshield,
Polyshield
Function principle - The closed combinedshield is a machine, which can be adapted todifferent excavating conditions mainly byaltering the excavation face support system.The following combinations have already beenused:l ) air pressure balance _ _ no pressure balance,2 ) slurry pressure balance _ _ no pressurebalance,3 ) earth pressure balance _ _ no pressurebalance,Main components of the machine_ rotating cutterhead (rotates with cutterspokes more or less closed);_ protective shield;_ thrust system:longitudinal jacks.
Main field of application - The versatility ofcombined closed shields lends them to be usedin rocks and soils under the groundwater tablewith limited or no self -supporting capacity.
3. Conditions for TunnelConstruction and Selection of TBMTunneling Method
3.1. Investigations
3.1.1. Introduction
In underground works, construction inducescomplex and often time-dependent soil-structure interaction. Design must thereforedevelop both of the basic aspects, whichdetermine the interaction: statics of theexcavation and the construction methodemployed.
The success of a project, in terms of time andcosts, strongly depends on the method ofexcavation employed and the timing of thevarious construction phases.
The planning of investigation and tests musttake into account these considerations andmust be inserted into a well-defined designplanning.
Figure 3.1 shows the schematic structure ofthe“Guidelines for Design, Tendering andConstruction of Underground Works adoptedby the main Italian Engineering Associationsin relation to tunneling.These“guidelines”a r e based o n theidentification of the“key points”and theirorganization into“subjects”representing thevarious successive aspects of the problem to beanalyzed and quantified during design/ -tendering/construction. The degree of detail ofeach“key point”will depend on the -Peculiarities of the specific project and designstage.In general planning for design, tendering andconstruction, as illustrated in Figure 3.2, thevarious“key points”and“subjects”are linked.The relationship between site investigations(Geological Survey and/or Geotechnical -geomechanical studies) and the Preliminarydesign of excavation and support (Choice ofexcavation techniques and support measures) isindicated.
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F gure 3.1 Schematic structure of the Guidelines for Design, Tendering and Construction ofUnderground Works
1. Main Themes 2. Key points 3. Subjects
_ Functional Requirements_ Design Constraints_ Environmental Aspects_ Comparative analysis of alternative routes
_ Collection and examination of technical documents_ Assessment of the degree of completeness of the design
_ General technical judgment of project and recommendations_ Indication of possible design adjustments_ Considerations regarding possible alternatives_ Special conditions for tendering and construction
_ Literature review
_ Structure_ Stratigraphy_ Geomorphology_ Hydrology and Hydrogeology
_ Evaluation of interaction with geotechnical and geomechanical investigations (C2)_ Planning of site investigations
_ Structural geological setting_ Meso – structural features_ Lithostratigraohic features_ Mineralogical and petrographic features_ Reliability of the qeoloqical model
_ Geomorphological setting_ Interaction between morphogenetic dynamics and designed structures
_ General Hydrology and Hydrogeology_ Water Chemistry_ Structure acquifer interaction_ Presence of other fluids
_ Seismicity of the area and neotectonic aspects
A2.Critical examination of previous design stages
A3.Codes and standards
B1.Acquisition of available data
B2.Preliminary geological model
B3.Site investigations
B4.Final geological model
B5.Geomorphology
B6.Hydrology and hydrogeology
B7.Geothermal studies
B8.Seismicty
GENERALSETTING OF THEUNDERGROUNDWORK
GEOLOGICALSURVEY
A
B
A1.General setting of the works and its relationship with the general design
A4.Reccommendations for subsequent stages of design and construction
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4. Main Themes 5. Key points 6. Subjects
_ Review of data from geological study_ Review of data from literature
_ Evaluation of the relation-ship withsite investigation (B3)
_ Planning of investigation and tests_ Summary of results_ Additional investigations
_ Soil and rock-mass structure
_ Soil and intact rock characterization
_ Mechanical characterization of discontinuities
_ Hydraulic properties of soil and rock masses
_ Geomechanical classification of rock masses
_ Geotechnical and geomechanical models
_ Calculation of behavior of face and profile of excavation without support
_ Effects of underground excavations on the surface
_ Effects of excavation on the surrounding mass
_ Effects of tunneling on the existing hydrogeologic equilibrium
_ Study of different methods of excavation and suppout:traditional and mechanized_ Choice of general criteria for construction
C1.Preliminaryl ti
C2.Geotechnical andgeomechanicalinvestigations
C3.Soil or rock masscharacterization
C4.Natural state of stress
D1.Subdivision of the routeinto“homogeneous”zones
D2.Evaluation of the excavationstability conditions for eachhomogeneous zone
D3.Surface and undergroundconstraints
D4.Preliminary design of methods of excavation and
support
GEOTECHNICALGEOMECHANICALSTUDIES
PREDICTION OFMECHANICALBEHAVIOR OF THEMASSES
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_ Definition of applicable methods ofexcavation
_ Definition of section type_ Design of the stabilization interventions
_ Design loads_ Model of construction phases_ Structural design of final lining_ Design of finishing
_ Evaluation of the safety factors_ Crisis scenarios and collapse hypothesis_ Definition of counter measures
_ Design of portals_ Ventilation systems_ Monitoring plan_ Disposal and borrow areas_ Ancillary works_ Construction sites and access roads_ Environmental impact study
_ Technical documents which form part of the contract_ Plan of safety and coordination
_ Geological survey_ Hydrogeological measurements_ Geomechanical measurements_ Monitoring stress-strain response_ Monitoring the state of stress and strain in the lining_ Effectiveness of consolidation and stabilization measures_ Monitoring nearby structures above and below ground
E1.Choice of excavation techniques and support measures for each homogeneous zone
E2.Structural design
E3.Evaluation of safety index
E4.Design optimization
F1.Design of auxiliary works
F2.Tender documents
G1.Monitoring duringconstruction
G2.Checking validity ofdesign and abjustmentsduring construction
DESIGN CHOICESAND CALCULATIONS
DESIGN OFAUXILIARY WORKSAND TENDER
MONITORINGDURINGCONSTRUCTIONAND OPERATION
G3.Auditing
G4.Monitoring during operation
_ Probabilistic evaluation of construction times and costs of the design solution
_ Comparison between design assumption and measurements during construction_ Adjustments of design according to the observed differences
_ Structural auditing_ System auditing
_ Monitoring of stress and strain in ground-stucture complex_ Hydrogeological measurements_ Surveys
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Soil
and
rock
mas
sch
arac
teri
zatio
n
Subd
ivis
ion
into
"hom
ogen
cous
"zon
es
Eva
luat
ion
of e
xaca
vatio
nst
abili
ty f
or e
ach
hom
ogen
eous
zon
em
etho
ds o
f ex
cava
tion
and
supp
ort
Surf
ace
and
unde
rgro
und
cons
trai
nts
Cho
ise
of e
xcav
atio
nte
chni
ques
and
sup
port
mea
sure
sSt
ruct
ural
des
ign
Eva
lutio
n of
the
safe
ly in
dex
Des
ign
optim
izat
ion
Des
ign
of a
uxili
ary
wor
ks
Mon
itori
ng d
urin
gco
nstr
uctio
nC
heck
ing
valid
ity o
fde
sign
and
abj
ustm
ents
Aud
iting
GeologicalGeneral setting ofunderground works
Geotechnical-geomechanical
studies
Prediction of mechanicalbehavior of the masses
Design choiseand calculation
Des
ign
of a
uxili
ary
wor
ks a
nd te
nder
doc
umen
ts
Mon
itori
ng d
urin
g co
nstr
uctio
n an
d op
erat
ion
Mon
itori
ng d
urin
g op
rrat
ion
Tend
er d
ocum
ents
III-12
3.1.2. Parameter selection
In line with the general criteria discussed in the previoussection the parameters to be investigated for obtaininguseful information for mechanized tunnel design andconstructionhave been divided in two categories:
1. geological parameters;2. geotechnical - geomechanical parameters.
In the first category, the parameters are common to alltunnel studies and/or design, not restricted to mechanizedtunneling (Table 3.1).
The geotechnical - geomechanical parametersspecifically to mechanized tunneling arepresented in Table 3.2.
In accordance also with the work carried out by theFrench Tunneling Association -(AFTES),the parameters have been divided in different groups:
l. state of stress,2. physical,3. mechanical,4. hydrogeological,5. other parameters.
The following information are reported for each group inTable 3.2:a) the parameter symbol (s)
b) the relationship with TBM excavation, in terms of: _ tunnel face and cavity stability _ cutting head _ cutting tools _ mucking system
c) the stage of the work in which the parameter isrequired, in terms of:
_ FS feasibility study/preliminary design _ DD detailed design _ DC construction stage
d) notes related to particular conditions.
III-13
Table 3.1: Geological parameters and investigations required for thedesign of mechanized tunnel excavation
No. OBJECTIVE OF INVESTIGATION INVESTIGATION TYPEGEOLOGICAL
12
Regional structural settingMesostructural and lithostratigraphic features
TopographyPhotogrammetryPhotointerpretationRemote sensingRegional geological studies and mapping
Detailed geological studies and mapping3 Type of soils/rocks Detailed geological studies and mapping
Boreholes4 Soils/rocks structure (fabric, stratification,
fracturing)Detailed geological studies and mappingBoreholes
56
Overburden and layers thickness ,Degree and depth of weathering
Detailed geological studies and mappingGeophysical methodsBoreholes
7 Geological structural discontinuities (faults,shear zones, crushed areas, main joints)
Detailed geological studies and mappingGeophysical methodsBoreholes
8 Special formation (salt, gypsum, tale, organicdeposits)
Detailed geological studies and mapping ,Boreholes
9 Karst phenomena: location of cavities, degreeof karstification, age and origin, infilling andkarst water
Detailed geological studies and mappingSpeleological studiesBoreholesMicro-gravimetric survey
GEOMORPHOLOGY
10 General geomorphological condition TopographyPhotogrammetryPhotointerpretationRegional geomorphological studies and mappingDetailed geomorphological studies and mapping
11 Active or potentially active processes Detailed geomorphological studies and mapping
HYDROLOGY AND HYDROGEOLOGY12
13
Hydrologic condition
Groundwater features ( swampy ground areas,springs or seepage position, notes ongroundwater properties )
TopographyPhotogrammetryPhotointerpretationRegional hydrological studies and mappingDetailed hydrological studies and mappingDetailed geological studies and mappingDetailed hydrogeological studies and mapping
14 No. of groundwater bodies, groundwaterlevels ( and potential groundwater levels )
Detailed hydrogeological studies and mappingBoreholes
15 Soil/rock masses permeability types Detailed hydrogeological studies and mappingGEOTHERMAL CONDITIONS
16 Hydrotermal conditions Regional geological studies17 Gas emanations Regional geological studies and mapping
Detailed geological studies and mappingBoreholes
SEISMICDONDITIONS
18 Seismicity Regional geological studies
III-
14
Tab
le 3
.2:
Geo
-Par
amet
ers
rela
ted
to
mec
han
ized
tu
nn
elin
g
Rel
atio
nshi
p w
ith T
BM
exc
avat
ion
Exc
avat
ion
Stag
e of
the
wor
k in
whi
ch th
epa
ram
eter
is r
equi
red
No.
PAR
AM
ET
ER
Sym
bol
Tun
nel f
ace
and
cavi
tyst
abili
tyC
uttin
g he
adC
uttin
g to
ols
Muc
king
syst
emF
SD
DD
CN
OT
E
1ST
AT
E O
F S
TR
ESS
1.1
1.2
1.3
1.4
1.5
Nat
ural
str
ess
Ver
tical
str
ess
Hor
izon
tal/V
ertic
al t
otal
str
ess
ratio
Hor
izon
tal/V
ertic
al e
ffec
tive
stre
ss r
atio
Co
nso
lid
atio
n
deg
ree
(com
pact
ion,
deco
mpr
.)
σ 1,σ
2,σ 3
,σ v
Kt_
(σh/
σ v)
KO
R S/R
S/R S S
S/R
S/R
A A A A
A N N N NO
A-O N
2P
HY
SIC
AL
2.1
Inde
x pr
oper
ties
2.11
2.12
2.13
2.14
2.15
2.16
Vol
umet
ric
wei
ght
Wat
er c
onte
nt, s
atur
atio
n de
gree
, voi
d ra
tioPl
astic
ity i
ndex
Gra
nulo
met
ric
char
acte
rist
ics
Act
ivity
Min
eral
ogic
and
pet
rogr
aphi
c fe
atur
es
γ,γd
,γs,
w, S
i, e
wl,
wn
S/R
S/R S S
S/R
S/R S S
S/R S S/R
S/R
S/R
S/R S
A A A A A A
N-O
N-O
N-O
N-O
N-O
N-O
A A A A A A
Abs
olut
ely
nece
ssar
y in
so
ftgr
ound
2.2
Glo
bal e
valu
atio
n qu
ality
2.21
2.22
2.23
Gen
eral
qua
lity
inde
xA
ltera
tion
inde
xQ
ualit
y in
dex
AM t O
S/R R R
S/R R R
R R
N-O
N-O
A-O
N
2.3
Dis
cont
inui
ties
2.31
2.32
2.33
Dis
cont
inui
ties
dens
ityN
umbe
r of
set
sSe
ts c
hara
cter
istic
s:_
Ori
enta
tion
(dip
and
dip
dir
ectio
n)_
Spa
cing
_ P
ersi
sten
ce_
Rou
ghne
ss_
Ape
rtur
e_
Inf
illin
g_
See
page
_ S
hear
str
engt
h_
Gen
esis
(fo
liatio
n, j
oint
)
RQ
D,λ
Nl,
NX
R R R
R R R
N-O A A
N-O
N-O
N-O
N N N
III-
15
Rel
atio
nshi
p w
ith T
BM
exc
avat
ion
Exc
avat
ion
Stag
e of
the
wor
k in
whi
ch th
epa
ram
eter
is r
equi
red
No.
PAR
AM
ET
ER
Sym
bol
Tun
nel f
ace
and
cavi
tyst
abili
tyC
uttin
g he
adC
uttin
g to
ols
Muc
king
syst
emF
SD
DD
CN
OT
E
2.4
Wea
ther
abili
ty
2.41
2.42
2.43
Sens
ibili
ty t
o w
ater
, sol
ubili
tySe
nsib
ility
to
hydr
omet
ric
vari
atio
nsSe
nsib
ility
to
ther
mic
var
iatio
ns
S/R
S/R
S/R
S/R
S/R
S/R
S/R
S/R
A AN
-ON
-O A
A A AN
ot f
requ
ently
use
d
2.5
Wat
er c
hem
istr
y
2.51
2.52
Che
mic
al c
hara
cter
istic
sW
aste
con
ditio
nsS/
RS/
RA
N-O N
A N3
ME
CH
AN
ICA
L
3.1
Stre
ngth
3.11
3.12
3.13
3.14
3.15
Shea
r (s
hort
tim
e)U
niax
ial
com
pres
sive
Tens
ileR
esid
ual
Gen
eral
str
engt
h in
dex
τs f
,σc
σ t, I
S
S/R
S/R R S/R
S/R
S/R
S/R R S/R
S/R
S/R R
N(S
)N
(R)
A-O A
N-O
N-O
N-O
A-O
A A A A A3.
2G
loba
l eva
luat
ion
qual
ity
3.21
3.22
3.23
3.24
Ani
sotr
opy
elas
tic c
onst
ants
Isot
ropi
c el
astic
con
stan
tsV
isco
-beh
avio
rSw
ellin
g
E,υ
E(t
), E
(q)
R S/R
S/R
S/R
R S/R
S/R
N-O A N
A N-O
N-O
N-O
A A A A3.
3D
ynam
ic c
hara
cter
istic
s of
soi
l/roc
k m
ass
3.31
3.32
3.33
P an
d S
wav
es v
eloc
ityD
efor
mab
ility
mod
ules
Liq
uefa
ctio
n po
tent
ial
S/R
S/R S
A A A
N-O
N-O
N-O
A A A
4H
YD
RO
GE
OL
OG
ICA
L4.
14.
24.
34.
4
Ani
sotr
opy
perm
eabi
lity
Isot
ropi
c pe
rmea
bilit
yPi
ezom
etri
c le
vel,
hydr
aulic
gra
dien
tW
ater
flo
w
k X, k
V, k
Z,
k H, i Q
S/R
S/R
S/R
S/R
S/R
N-O N
A-O
N-O
N-O
A-O
N-O
N-O
III-
16
Cut
ting
head
Cut
ting
tool
s
5O
TH
ER
PA
RA
ME
TE
RS
5,1
Abr
asiv
ityS/
RS/
RA
-ON
-O5,
2H
ardn
ess
RR
A-O
N-O
All
thes
e pa
ram
eter
s ar
e pa
rticu
larly
5,3
Dril
labi
lity
RN
-Ore
quir
ed f
or m
echa
nize
d tu
nnel
ing
5,4
Stic
ky b
ehav
ior
S/R
S/R
S/R
A-O
N-O
A5,
5G
roun
d fr
ictio
nS/
RA
A-O
A-O
S=So
il; R
=Roc
kFS
=Fea
sibi
lity
Stud
y/Pr
elim
inar
y D
esig
n, D
D=D
etai
led
Des
ign;
DC
=Dur
ing
Con
stru
ctio
nN
=Nec
essa
ry; A
=Adv
isab
le; O
=Qua
ntifi
catio
n of
this
par
amet
er is
don
e th
roug
h sp
ecifi
c te
sts
Exc
avat
ion
Muc
king
syst
em
NO
TE
No.
PAR
AM
ET
ER
Sym
bol
Stag
e of
the
wor
k in
whi
ch t
he p
aram
eter
is
requ
ired
FS
DD
DC
Rel
atio
nshi
p w
ith T
BM
exc
avat
ion
Tun
nel
face
an
d ca
vity
st
abili
ty
III-
17
Tab
le 3
.3:
Ge
o-p
ara
met
ers
an
d r
elat
ed i
nves
tig
atio
ns
No .
PA
RA
ME
TE
RIN
VE
ST
IGA
TIO
N T
YP
EL
oca
tio
nS
=si
te
L=
=L
ab.
NO
TE
1S
TA
TE
OF
ST
RE
SS
1.1
1.2
1.3
1.4
1.5
Nat
ural
str
ess
Ver
tica
l st
ress
Ho
rizo
nta
l/V
erti
cal
tota
l st
ress
rat
io
Ho
rizo
ntal
/Ver
tica
l ef
fect
ive
stre
ss r
atio
Co
nso
lid
atio
n
deg
ree
(co
m
acti
on
,d
ecom
pr.)
Bo
reh
ole
Slo
tter
str
essm
eter
met
ho
d (
R)
Ov
erco
rin
g m
eth
od
s (R
)
Hy
dra
uli
c F
ract
uri
ng
Tec
hn
iqu
e (R
) '
Dil
ato
met
er (
S/R
)A
edo
met
er
test
w
ith
la
tera
l p
ress
ure
co
ntr
ol
(S)
Tri
axia
l te
st
wit
h
late
ral
def
orm
atio
n
con
tro
l(S
)D
ilat
om
eter
(S
/R)
Fla
t ja
ck m
etho
d (R
)M
arch
etti
dil
ato
met
er (
S)
Oed
omet
ric
test
(S
)O
edom
etri
c te
st (
S)
S S S S S L L S S S L L
In b
ore
hol
e te
stIn
bo
reh
ole
test
In b
ore
hol
e te
stM
in.
5-6
tes
ts a
re r
equ
ired
, u
sefu
lal
so f
or
soft
ro
ckE
xp
erim
enta
l m
eth
od
No
t fr
equ
entl
y us
edN
ot
freq
uen
tly
used
Ex
per
imen
tal
met
ho
d
2PH
YSI
CA
L2.
1In
dex
prop
ertie
s1.
11
2.12
2.13
2.14
2.15
2.16
Un
it w
eigh
t
Wat
er
con
ten
t,
satu
rati
on
d
egre
e,
void
inde
xP
last
icit
y i
nde
xG
ranu
lom
etri
c ch
arac
teri
stic
s
Act
ivit
yM
iner
alo
gic
an
d p
etro
grap
hic
fea
ture
s
Den
sity
tes
ts (
S/R
)G
amm
a-d
ensi
met
er (
S)
Lab
ora
tory
in
dex
tes
ts (
S/R
)A
tter
berg
lim
its
(S)
Gra
in-s
ize
anal
yse
s an
d
sed
imen
tati
on
anal
yse
s (S
)P
etro
grap
hic
an
aly
ses
(R)
Min
eral
og
ic a
nal
yse
s (S
)M
iner
alo
gic
an
aly
ses
(S/R
)P
etro
grap
hic
an
aly
ses
(S/R
)C
hem
ical
an
aly
ses
(S/R
)
L S L L L L L L L L
2.2
Glo
bal e
valu
atio
n of
qua
lity
2.21
2.22
Gen
era
qual
ity
inde
x
Alt
erat
ion
inde
x
Geo
ph
ysi
cal
met
hods
: .s
eism
ic,
geo
elec
tric
,m
icro
gra
vim
etri
c, g
eora
dar
(S
/R)
Bo
reh
ole
per
fora
tio
n
par
amet
ers:
ve
loci
ty,
torq
ue,
pre
ssu
re (
S/R
)V
isu
al e
xam
inat
ion
of
the
mat
eria
l (R
)S
lake
du
rab
ilit
y te
st (
R)
S S S L
Qu
alit
ativ
e ev
alua
tion
Ou
tcro
ps,
inve
stig
atio
n ga
ller
ies,
bo
reh
ole
sam
ple
s
III-
18
No.
PAR
AM
ET
ER
INV
EST
IGA
TIO
N T
YPE
Lo_a
tion
S=si
teL
=Lab
NO
TE
2,23
Qua
lity
inde
xSo
nic
wav
es te
st (R
)L
Min
eral
ogic
al a
naly
sis
(R)
LPe
trogr
aphi
c an
alys
is (
R)
L2,
3D
isco
ntin
uitie
s2,
31D
isco
ntin
uitie
s den
sity
Site
mea
sure
men
ts (
R)
SO
utcr
opR
ock
Qua
lity
Des
igna
tion-
RQ
D (R
)S/
LB
oreh
ole
sam
ples
Seis
mic
_ur
vey(
R)
SQ
ualit
ativ
eev
alua
tion
2,32
Num
ber
ofse
tsSi
te m
easu
rem
ents
+ s
tere
ogra
phic
ana
lyse
s (R
)S/
L2,
33Se
ts c
hara
cter
istic
s:1.
Orie
ntat
ion
(dip
and
dip
dire
ctio
n)1.
Site
mea
sure
men
t1.
S2.
Spac
ing
2. S
ite m
easu
rem
ent
2.S
3. P
ersi
sten
ce3.
Site
mea
sure
men
t3.
S_.
Rou
ghne
ss4.
Site
mea
sure
men
t4.
S5.
Ape
rture
5. S
ite m
easu
rem
ent
5.S
6.In
fillin
g6.
Site
obs
erva
tion
and_
min
eral
ogic
al te
st6.
S7.
Seep
age
7. S
ite m
easu
rem
ent
7.S
8.
Shea
r st
reng
th8.
Shea
rtes
t8.
L9.
Gen
esis
(fol
iatio
n, b
eddi
ng, j
oint
)9.
Geo
logi
cal o
bser
vatio
ns9.
S2,
4W
eath
erab
ility
2,41
Sens
itivi
ty to
wat
er, s
olub
ility
Site
obs
erva
tion
(S/R
)S
Min
eral
ogic
al a
naly
ses
(S/R
)L
Swel
ling
test
(R)
Let
c.)C
yclic
test
s (w
et-d
ry) (
R)
LSo
lubi
lity
test
(R)
L2,
42Se
nsib
ility
to h
ygro
met
ric v
aria
tions
Min
eral
ogic
ana
lyse
s (S
/R)
LSi
te o
bser
vatio
n (S
/R)
S2,
43Se
nsib
ility
to th
erm
ic v
aria
tions
Hea
ting
test
(S/R
)L
Free
zing
test
(S/R
)L
2,5
Wat
er c
hem
istry
2,51
Che
mic
alch
arac
teris
tics
Che
mic
al a
naly
ses:
sal
t co
nten
t, a
ggre
ssiv
ity,
Lha
rdne
ss, p
H v
alue
, tem
pera
ture
, etc
.2,
52w
aste
con
ditio
nsC
hem
ical
ana
lyse
sL
3M
EC
HA
NIC
AL
3,1
Stre
ngth
3,11
Shea
r (s
hort
time)
Cas
agra
nde
shea
r bo
x te
st, u
ndra
ined
con
ditio
ns (
S)S/
LD
irect
She
ar te
st (R
)L
In s
itu d
irect
she
ar te
st (
R)
STr
iaxi
al te
st (S
/R)
S/L
Soils
: l
ower
lim
it va
lues
; r
ocks
: u
pper
lim
it va
lues
Scis
som
eter
/ V
ane
test
(S)
S/L
Incl
ayed
bore
hole
sam
ples
III-
19
No.
PA
RA
ME
TE
RIN
VE
STIG
AT
ION
TY
PE
Loc
atio
nS=
site
L=
Lab
NO
TE
3,12
Uni
axia
l co
mpr
essi
veU
niax
ial
com
pres
sion
tes
t (S
/R)
LPo
intl
oad
test
(R)
S/L
Indi
rect
mea
sure
men
t of
the
par
amet
er3,
13T
ensi
leD
irec
t ten
sile
test
(R
)L
Bra
zili
ante
st(R
)L
Indi
rect
mea
sure
men
t of
the
par
amet
erPo
intl
oad
test
(R)
S/L
_ndi
rect
mea
sure
men
t of
the
par
amet
er3,
14R
esid
ual
Res
idua
l st
reng
th t
est
(she
ar, t
riax
ial
test
s)S/
L3,
15G
ener
al s
tren
gth
inde
xB
oreh
ole
per
fora
tion
pa
ram
eter
m
easu
rem
ents
:ve
loci
ty, t
orqu
e, p
ress
ure
(S/R
)3.
,2D
efor
mab
ility
3,21
Isot
ropi
c/A
niso
trop
icel
_stic
cons
tant
sPl
ate
load
ing
test
(R
/S)
SR
ock
surf
ace
test
Dir
ectio
nal d
ilato
met
er te
st (
S/R
)S
Insi
debo
reho
lete
sts
Uni
axia
l -T
riax
ial
com
pres
sive
tes
ts o
n di
rect
iona
lL
sam
ples
(S/
R)
P-S
wav
e m
easu
rem
ent
(_/R
)S/
LQ
uali
tati
vem
easu
rem
ent
Def
orm
atio
n m
easu
rem
ent
(S/R
):S
Roc
k su
rfac
e te
st (
i.e. e
xper
imen
tal-
_. C
onve
rgen
ce/d
ilata
ncy
galle
ry)
2.
Ext
enso
met
er3.
In
clin
ome_
ers
4. S
ettle
men
ts3,
22V
isco
-beh
avio
rFl
at ja
ck m
etho
d (R
)S
Roc
ksu
rfac
ete
stL
ong-
time
plat
e lo
adin
g te
st (
R)
SR
ock
surf
ace
test
C
reep
load
test
(S)
LC
ycle
dila
tom
eter
test
(S/
R)
SIn
side
bore
hole
test
s_e
form
atio
n m
easu
rem
ents
(S/
R)
SR
ock
surf
ace
test
3,23
Swel
ling
Swel
ling
test
(S/R
)L
/S3,
3D
ynam
ic c
hara
cter
isti
cs o
f so
il/r
ock
mas
s3,
31P
and
S w
aves
vel
ocity
Seis
mic
sur
vey:
cro
ss-h
ole,
dow
n-ho
leS
Insi
debo
reho
lete
s_s
3,32
Def
orm
abili
tym
odul
esSe
ism
ic s
urve
y: c
ross
-hol
e, d
own-
hole
SIn
side
bor
ehol
e te
sts
3,33
Liq
uefa
ctio
npo
tent
ial
Stan
dard
pen
etra
tion
tes
tS
Insi
debo
reho
lete
sts
4H
YD
RO
GE
OL
OG
ICA
L4,
1A
niso
trop
icpe
rmea
bilit
yO
bser
vatio
n du
ring
bor
ehol
e dr
illin
gS
Qua
litat
ive
dete
rmin
atio
nPe
rmea
bilit
yte
sts:
SIn
side
bor
ehol
e te
ests
1.
Lef
ranc
2.
Lug
eon
3. D
irec
tiona
l, co
nsta
nt o
r va
riab
le w
ater
leve
l
III-
20
No.
PAR
AM
ETER
INV
ESTI
GA
TIO
N T
YPE
Loca
tion
S=sit
eL=
Lab
NO
TE
4.2
Isot
ropi
c pe
rmea
bilit
yPu
mpi
ngte
stS
Inje
ctio
n te
st S
4.3
Piez
omet
ric le
vel,
hydr
aulic
gra
dien
tPi
ezom
eter
(ope
nty
pe)
S P
iezo
met
er (c
lose
type
)S
4.4
Wat
er fl
ow
Tunn
el m
easu
rem
ents
S S
prin
gs m
easu
rem
ents
S
OTH
ER P
AR
AM
ETER
S5.
1A
bras
ivity
Abr
asiv
ity IS
RM
LC
erch
ar te
st (R
)L
Abr
asiv
ity (N
orw
egia
n In
stitu
re o
f Tec
hnol
ogy)
LLC
PT te
st (S
/R)
L5.
2
H
ardn
ess
Har
dnes
s IS
RM
(R
)L
Schm
ith h
amm
er (
R)
LLC
PT te
stL
Kno
opS/
LC
one
Inde
nter
test
(NC
B)
LPu
nch
test
(Col
orad
o Sh
ool o
f Min
es)
LD
rop
test
(Nor
weg
ian
Inst
itute
of T
echn
olog
y)L
Los A
ngel
es te
st (S
/R)
L5.
3D
rilla
bilit
y Si
ever
’ste
stL
Dril
labi
lity
tests
L5.
4St
icky
beh
avio
rM
iner
alog
ical
ana
lyse
s (S
/R)
LIn
dire
ct m
easu
rem
ent,
rela
ted
with
A
tterb
erg
limits
(S)
Lph
ysic
alin
dex
prop
ertie
s
III-21
In Table 3.3 an international standard is given for each investigation or test related to mechanized tunneling.Table 3.3: Investigations, test methods and references
METHODS REFERENCESITE INVESTIGATIONTopography,aerotopography,photogrammetryphotointerpretationEngineering geological investigationsGeophysical methods:_ micro-gravity_ seismic_ geoelectric_ georadarDrilling,borehore cameras and televisionTrenches,shafts and galleries
ISRM 1975
ISRM 1975
ASTM D4428-84
SITE TESTPlate loading test (R)Overcoring methods (R)Flat jack method (R)Hydraulic fracturing method (R)Compression Test (R)Direct shear test (R)Dilatometer (S/R)Standard penetration test: SPT (S)Cone penetration test: CPT (S)Rock Quality Designation (RQD)Vane Shear Test (S)Discontinuities (R)Deformation measurements (S/R):1. Convergence/dilatancy2. Extensometer3. Inclinometers4. SettlementsLong-time plate bearing test (R)Creep test (S/R)Cycle dilatometer test (S/R)Deformation measurements (S/R)Permeability tests:1. Lefranc2. Lugeon3. Directional, constant or variable, water levelPumping testInjection testPiezometer (open type)Piezometer (close type)Tunnel measurements
ISRM11 / ISRM19 / ASTM D4394-84 / ASTM D4395-84ASTM D4623-86ASTM D4729-87ASTM D4645-87ASTM D4555-90
ASTM D4971-89 / ASTM D4506 -90ASTM D1586-84 / ASTM D4633 - 86ASTM D3441-86
ASTM D2573-72ISRM07 / ISRM14 / ASTM D4554 - 90
ASTM D4553-90
ASTM D2434-68
ASTM D4750-87
LABORATORY - SOILIdentification tests :_ Volumetric weights (natural, dry, satured)_ natural water content, saturation degree_ porosity, void ratio_ Atterberg limits_ Activity (clay)
ASTM D4318-84 / ASTM D4254-83 / ASTM D3282-88ASTM D2487-90 / ASTM D4404-84 /ASTM D4959-89 / ASTM D854-83ASTM D427-83 / ASTM D2210-90
III-22
METHODS REFERENCE
Grain-size analyses and sedimentation analysesGamma-densimeterMineralogic analyses (diffractometer)Chemical analysesPermeabilityOedometric test:_ Natural consolidation_ compressibility characteristics (consolidation
index, edometric compressibility index)_ permeability_ swelling pressure/ swelling indexswelling test (Huder-Amberg)Shear test:_ total coesion_ total frictional angleTriaxial test:_ drained coesion_ drained frictional angle_ undrained coesion_ total coesion_ total frictional angle
ASTM D422-63 / ASTM D2487-90 / ASTM D1140-54
ISRM 1977 / ASTM D4452-85
ASTM D2438-90ASTM D4186-90 / ASTM D2435-90 / ISRM 89ASTM D2435-90 / ASTM D2166-85
ASTM D3080-90 / ASTM D2435-90
ASTM D4767-88 / BS1377 / ASTM D2850-87
LABORATORY - ROCKIndex laboratory tests:_ Density_ natural water content_ porositySlake durability testPetrographic analysesMineralogic analysesChemical analysesUniaxial compression test (R)Point load test (R)Triaxial test (R)
Direct Shear test (R)Direct tensile test (R)Brazilian test (R)CreepSonic waves test (R)Swelling test (R)Cyclic tests (wet-dry) (R)Solubility test (R)Thermal expansion test (S/R)Frozing test (S/R)Abrasivity_ Abrasivity_ Cerchar test (CAI index)_ Abrasivity test (AV – AVS)Hardness_ Hardness_ Schmith hammer_ Knoop_ Cone Indenter (INCB)_ Punch test_ Los Angeles test (S/R)
ISRM09
ISRM09 / ASTM D4644-87ISRM01
ISRM08 / ASTM D3148-86 / ASTM D2938-86ISRM16 / ISRM25ISRM02 / ISRM13 / ASTM D2664-86ASTM D4767 / BS1377 / AGI 1994ISRM05 / ASTM D2936-84 / ASTM D3967-86ISRM24
ASTM D4341-84 / ASTM D4406-84 / ASTM D4405-84ASTM D2845-90 / ISRM03ISRM09
ASTM D4611-86
ISRM04West 1989NIT 1990
ISRM04ISRM 1977
National Coal Board, UK, 1964
III-23
METHODS REFERENCEDrillability
• Sievers test NIT 1990
• Drillability test
• Resistance to crushing : Drop test NIT 1990
LABORATORY - WATERChemical analyses:_• salt content / organic materials Standard Methods for examination of wa
• aggressivity_ waters. American Public Health Associa
• hardness• pH value
• temperature
III-24
3.1.3. Monitoring during construction
The deterministic design of a tunnel is based onjudgment in selecting the most probablevalues within the ranges of possible values ofengineering properties. As construction -progresses the geotechnical - geomechanical conditionsare observed, work performance ismonitored and the design judgments can be evaluatedor, if necessary, updated. Thus,engineering observations during tunnel works are oftenan integral part of the design process,and geotechnical - geomechanical -instrumentation is a tool, which assists with theseobservations.
From a general point of view, the scope of themonitoring scheme is to:
A. control the stability and stress - strain conditions ofthe structures in the new underground construction;
B. control the stability and stress-strain conditions ofthe existing structures which potentially interfere withthe new construction; and
C. control ground movement around the newunderground constructions;
D. monitor environmental aspects.
The design of the general monitoring scheme comprisesthe following activities:
1. identification of the significant parameters whichneed to be monitored in consideration of: _ construction geometries and materials; _ stability of existing structures (surface and/or
underground) and their potentialinterference with the new construction;
_ geotechnical – geomechanical parameters of theground and their range of variation;
_ geo-structural calculations and structural analysis;and
_ construction sequence.
2. definition of the adequate types of instruments;
3. specification of the caution and alarm values for eachparameter to be monitored;
4. definition of the counter – measures in case thatcaution and/or alarm leveis are exceeded.The different investigation/monitoring possibilities are _ from ground surface, or from underground _ before, during and after excavation.In the following subsections we will only examine theunderground investigation/-monitoring systems specifically related to TBMtunneling (investigation before -excavation and monitoring during excavation from
underground).
3.1.4. TBM tunneling monitoring system
Monitoring systems are used to study the stress-strainbehavior of the surrounding ground and lining duringand after -construction.
The use of a TBM for the construction of a tunnel doesnot permit continuous, directobservation of the ground being excavated.Therefore, all the necessary geological-geomechanical information required both during theconstruction phase for evaluating the ground conditionsahead of the excavation face and subsequently for thepurpose ofdocumentation when the work is completed, arenormally obtained using indirect methods.
Usually the studies on the interaction between thesoil/rock mass and the TBM aim tocharacterize the quality of the ground mass, above all,to assess its borability.
However, the current problem is an inverse one: giventhat there is no question that the groundcan be excavated, efforts must be focused on thecharacterization itself through analysis andelaboration of all construction parameters that couldpossibly be recorded.
Through precise and objective documentation of whatthe TBM encounters during excavationit is possible to derive the principal -characteristics of the soil/rock mass because variationsin TBM behavior are usually correlated with changes inthe geotechnical-geomechanicalsituations.
It is important to underline right from the outset that theprerequisites for making a correctevaluation of the ground mass using all the constructionparameters that can possibly berecorded may be summed up as follows:_ the use of a TBM fitted with appropriate
instrumentation._in this approach skilled engineering geologists with
experience should be employed to collect andinterpret all the relevant data.
_ The data collected should be stored in a dynamicdatabase so that multiple-parametercorrelation can be not only established but alsocontinuously updated in quasi-real time, as well asoffering the possibility to carry out ground conditionsextrapolation and forecasting.
From a tunnel excavated by TBM it is possible toinvestigate the ground ahead of the tunnelface using the methods listed it Table 3.4.
III-25
The TBM monitoring systems which can be used tocollect data during tunnel construction are listed inTable 3.5.
III-26
Table 3.4: Types of soil/rock mass investigations used ahead TBM face
INVESTIGATION TYPE NOTE
Direct investigation
Boreholes with core recovery Horizontal boreholes are normally performed through the TBMcutting head; inclined boreholes are normally possible immediatelybehind the cutting head in open TBM, through the shield in shieldedTBM. Radial boreholes are possible in all TBM types through thelining.
The objective of boreholes is to:
_ determine the lithological nature of the ground to be excavatedthrough by the TBM.
_ determine the presence of water_ determine thepresence of voids (karst) and/or decompressed
zones;
The drilling is realized with a rig positioned behind the TBM cuttinghead. In the case of shielded TBMs, it is also possible to utilizea“preventer”system to avoid the ingress of groundwater to the tunnelduring execution of the drilling.
Horizontal and/or inclined boreholes with core-recovery is notcommonly used because the time and drilling diameter required.
Boreholes without core recovery The method of no-core-recovery with registration of the followingdrilling parameters using a data-logger.
_ drilling rate (VA, m/h) ;_ pressure on drill bit (PO,bar) ;_ pressure of the drilling fluid (PI, bar) ;_ torque (CR, bar) ;
It is possible to use either a drilling hammer or a tricone bit. Thediameter of the drill hole may be limited to 75mm, whereas thedrilling rods may be of the aluminum type in order to reduce potentialproblems associated with the advance of the TBM later in the casethat the drilling rods might be completely lost in the drill hole.
Geostructural mapping of the face and/orof the sidewalls
The mapping must be performed using the same methodologiesadopted for the face mapping in tunnels excavated by conventionalmethods.
This type of investigation can be performed only when the TBM stopsexcavation and thus it can be executed at more or less regularintervals in function of the various construction needs. The mappinginvolves the collection of all geological, structural and geomechanicaldata of the soil/rock mass. The purpose of this kind of investigationis:
_ direct characterization and classification of the soil/rock mass;_calibration of all construction parameters which may permit indirect
characterization of the rock mass.Indirect investigation
Georadar (in borehole)
Other borehole logs Gamma ray logNeutron logsGeoelectric logs
Seismic methods Tunnel Seismic Prediction method (TSP)Soft Ground Sonic Probing System (SSP)
Table 3.5: TBM monitoring systems
III-27
Category Parameter UdM TBMtype
Power kW
Torque Knm
Thrust KN
Rotation speed RPMCut
ting
head
Penetration rate mm/s
Consumption -
Exc
avat
ion
Cutting
tools Wedge position mm
All TBM
Air pressure kPa
Air discharge m3/h
Closed slurry shield (hydroshield)Compressed air close shield
Slurry pressure kPa
Slurry level mmClosed slurry shield
Supp
ort i
n th
e
exca
vatio
n
cham
ber
Earth pressure kPa Earth pressure balance shield
Slurry discharge m3/h
Slurry density kg/dm3
Discharge m3/h
Density kg/dm3
Closed slurry shield
Weight kN
Am
ount
Amount m3
Unshielded, single-double shielded TBM, mec.supported, comp. air, closed slurry and EPB shields
Petrographic characteristics -
Grain-size distribution -
Muc
king
Cha
ract
.
mechanical parameters -
All TBM (in slurry shield or EPB shield TBM is not required)
Shield position (x y z) m All TBM
Gripper thrust kN
Gripper stroke mm
Open TBM and some doubleshielded TBM
Jack thrust kN
Jacks stroke mm
Single-double shielded TBM, mec. suppoted, comp.
air, closed slurry and EPB shields TBM
Injection (through the shield) pressure kPa
Injection (through the shield) amount m3Closed slurry and EPB shield
Concrete injection pressure kPa
Oth
er p
aram
eter
s
Concrete injection amount m3
Shielded TBM with extrudedconcrete lining system
Excavation cycle (min. - med. - max.) h
Advance rate per shift/day/week/month m
Perf
orm
ance
Lining rings per shift/day/week/month N°
Planned (holidays, tools change, other ordinarymaintenance) h
Due to machine problem (mechanical, electrical, etc.) h
Due to unpredicted rock mass behavior, (water inflow,tunnel face and /or cavity instabilities, squeezing ground,karst, etc.) h
Due to lining problems h
Diverse (back-up problems, others) h
Con
stru
ctio
n da
ta
TB
M s
tops
Due to mucking system problems (slurry circuit, screwconveyor, belt conveyor, muck cars, etc.) h
All TBM
III-28
4. REFERENCES
A) ASTM (American Society for TestingMaterials)
D4750-87“Subsurface Liquid Levels in aBorehole or Monitoring Well(Observation Well ) ,Determining”.
D1140-54“Amount of Material in Soils Finerthan the No. 200 (75-_m) Sieve”.
D4428-84“Crosshole Seismic Testing”.D2487-90“Classification o f Soi ls for
Engineering Purposes”.D2166-85“Compressive Strength, Unconfined,
of Cohesive Soil”.D4767-88“Consolidated-Undrained Triaxial
Compression Test on CohesiveSoils”.
D4404-84“Determination of Pore Volume andPore Volume Distribution of Soiland Rock by Mercury IntrusionPorosimetry”.
D4959-89“Determination of Water (Moisture)Content of Soil by Direct HeatingMethod”.
D4829-88“Expansion Index of Soils”.D2573-72“Field Vane Shear Test in Cohesive
Soil”.D4318-84“Liquid Limit, Plastic Limit, and
Plasticity Index of Soils”.D2435-90“One-Dimensional Consolidation
Properties of Sails”.D4186-90“One-Dimensional Consolidation
Properties of Soils UsingControlled-Strain Loading” .
D2434-68“Permeability of Granular Soil(Constant Head)”.
D4719-87“Pressuremeter Testing in Soil”.D2844-89“Resistance R-Value and Expansion
Pressure of Compacted Soils”.D427-83 “Shrinkage Factors of Soils”.D854-83 “Specific Gravity of Soils”.D2850-87“Unconsolidated,Undrained
Compressive Strength of CohesiveSoils of Cohesive Soils in TriaxialCompression”.
D3441-86“Deep, Quasi-Static, Cone andFriction-Cone Penetration Testsof Soil”.
D3080-90“Direct Shear Test of Soils UnderConsolidated Drained -Conditions”.
D422-63“Particle-Size Analysis of Soils”.
D2216-90“Water (Moisture) Content of Soil,Rock, and Soil-Aggregate -Mixtures, Laboratory -Determination of ...”.
D4452-85“X-Ray Radiography of Soil -Samples”.
D4341-84“Creep of Cylindrical Hard RockCore Specimens in UniaxialCompression”.
D4406-84“Creep of Cylindrical Rock CoreSpecimens in Triaxial -Compression”.
D4405-84“Creep of Cylindrical Soft RockCore Specimens in UniaxialCompression”.
D4555-90“Deformability and Strength ofWeak Rock by Conducting an InSitu Uniaxial Compressive Test,Determining”.
D497l-89“Determining the In Situ Modulus ofDeformation of Rock UsingDiametrically Loaded 76-mm (3-in.) Borehole Jack”.
D2936-84“Direct Tensile Strengh of IntactRock Core Specimens”.
D3148-86“Elastic Moduli of Intact Rock CoreSpecimens in Uniaxial -Compression”.
D4553-90“In Situ Creep Characteristics ofRock,Determining”.
D4554-90“In Situ Determination of DirectShear Strength of Rock -Discontinuities”.
D4395-84“In Situ Modulus of Deformation ofRock Mass Using the FlexiblePlate Loading Method,Determining”.
D4506-90“In Situ Moudulus of Deformationof Rock Mass Using a RadialJacking Test, Determining”.
D4394-84“In Situ Modulus of Deformation ofRock Mass Using the Rigid PlateLoading Method, Determining”.
D4623-86“In Situ Stress in Rock Mass byOvercoring Method - USBMBorehole Deformation Gage,Determination of ...”.
D4729-87“In Situ Stress and Modulus ofDeformation Determination Usingthe Flat jack Method”.
D4645-87“In Situ Stress in Rock Using theHydraulic Fracturing Method”.
D4644-87“Slake Durability of Shales andSimilar Weak Rocks”.
III-29
D4611-86“Specific Heat of Rock and Soil”.D3967-86“Splitting Tensile Strength of Intact
Rock Core Specimens”.D2664-86“Triaxial Compressive Strength of
Undrained Rock Core SpecimensWithout Pore Pressure -Measurements”.
D2938-86“Unconfined Compressive Strengthof Intact Rock Core Specimens”.
D2845-90“Laboratory Determination of PulseVelocities and Ultrasonic ElasticConstants of Rock”.
B) ISRM (International Society of RockMechanic)
ISRM01“Suggested methods for petrographicdescription of rocks”. 1978,International Journal of RockMechanics. Mining Sciences andGeomechanical Abstract,vol. 15,n_2,pp. 41-46.
ISRM02“Suggested methods for determiningstrength of rock materials in triaxialcompression”. 1978, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol.15, n_2, pp. 47.52.
ISRM03“Suggested methods for determiningsound velocity”. 1978,InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol.15,n_2, pp. 53-58.
ISRM04“Suggested methods for determininghardness and abrasiveness of rocks”.1978, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.15,n_2,pp. 89-98.
ISRM05“Suggested methods for determiningtensile strength of rock materials”.1978,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.15,n_2,pp.-99-104.
ISRM06“Suggested methods for monitoringrock movements using boreholeextensometers”. 1978, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 15, n_6, pp. 305-318.
ISRM07“Suggested method f o r thequantitative description of -discontinuities in rock masses”.
1978, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 15,n_6, pp. 319-368.
ISRM08“Suggested methods for determiningthe uniaxial compressive strength anddeformability of rock materials”.1979, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.16,n_2,pp. 135-140.
ISRM09“Suggested methods for determiningwater content, porosity, density,absorption, and related properties andswelling and slake-durability indexproperties”. 1979, InternationalJournal of Rock Mechanics,MiningSciences and Geomechanical -Abstract, vol. l6, n_2, pp. 141-l56.
ISRM10“Suggested methods for determiningin situ deformability of rock”. 1979,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.16,n_3,pp. 195-214.
ISRM11“Suggested methods for pressuremonitoring using hydraulic cells”.1980, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 17,n_2, pp. 117-128.
ISRM12“Suggested methods for geophysicallogging of boreholes”. 1981,International Journal of RockMechanics, Mining Sciences andG e o m e c h n i c a l Abstract,vol.18,n_1,pp.67-84.
ISRM13“Suggested methods for determiningthe strength of rock materials intriaxial compression: revised -version”. 1983, International Journalof Rock Mechanics, Mining Sciencesand Geomechanical Abstract, vol. 20,n_6, pp. 283-290.
ISRM14“Suggested methods for surfacemonitoring movements acrossdiscontinuities”. 1984, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 21 , n_5, pp. 265-276.
ISRM15“Suggested methods for pressuremonitoring using hydraulic cells”.1985, International Journal of RockMechanics, Mining Sciences and
III-30
Geomechanical Abstract, vol. 22,n_2, pp. 51-60.
ISRM16“The equivalent core diameter methodof size and shape correction is pointload testing”. 1985, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 22, n_2, pp. 61-70.
ISRM17“Suggested methods for rocka n c h o r a g e testing”. 1985,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract,vol. 22, n_2,pp. 71-84.
ISRM18“Suggested methods for deformabilitydetermination using a large flat jacktechnique”. 1986, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 23, n_2, pp.131-140.
ISRM19“Suggested methods for rockdetermination”. 1987, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 24, n_ 1, pp. 53-74.
ISRM20“Suggested methods for deformabilitydetermination using a flexibledilatometer”. 1987, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 24, n_2, pp. 123-134.
ISRM21“Suggested methods for determiningthe fracture toughness or rock”. 1988,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 25, n_2,pp. 71-96.
ISRM22“Suggested methods for seismictesting within and betweenboreholes”. 1988, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 25, n_6, pp. 447- 472.
ISRM23“Suggested methods for deformabilitydetermination using a large flat jacktechnique”.
ISRM24“Suggested methods for determingShear Strength”. February 1974.
C) OTHER REFERENCES
ITA (International Tunneling Association),
1987, “Guidelines for Good TunnelingPractice”.
BTS (British Tunneling Society), 1997,“Model Specification for Tunneling”.
AFTES (Association Francaise des Travaux enSouterrain)
_Text of recommendations for a descriptionof rock masses useful for examination thestability of underground works (WorkingGroup n . l : Geology-geotechnicalengineering). 1993;
_Proposals concerning the measurementsand testing to be performed in connectionwi th a mechanical cut t ing :characterization of rocks and soils(Working Group n.4: Mechanizedexcavation), 1993.
SIG (Società Italiana Gallerie), 1997,“National Project for Design andConstruction Standards in UndergroundWorks Guidelines for Design, Tenderingand Construction of Underground Works”,Gallerie e Grandi Opere Sotterranee,marzo 1997.
AGI (Associazione Geotecnica Italiana), 1977,“Raccomandazioni sulla programmazioneed esecuzione delle indagini geotecniche”.
AGI (Associazione Geotecnica Italiana),1994,“Raccomandazioni sulle prove - geotecniche di laboratorio”.
SIA (Société Suisse des Ingégneurs et desArchitects), 1975, “Norma 199 conoscenzadei massicci rocciosi nei lavorisotterranei”. Zurich.
SIA (Société Suisse des Ingégneurs et desArchitects),1993, “NORMA 198 Lavori insotterraneo”. Zurich.
AUSTRIAN NORM, 1983, “ONORM2203”and “VORNORM 2203”, 1975.
D E U T S C H E R AU S S C H U S S FÜRUNTERIRDISCHES BAUE N: DAUB;ÖSTERREICHISCHE
GESELLSCAFT FÜR GEOMECHANIKUND ARBEITSGRUPPE TUNNELBAUDER FORSCHUNGESELLSCHAFT FÜRDAS VERKEHRS – UND -STRASSENWESEN: FACHGRUPPPE
III-31
FÜR UNTERTAGEBAU DES -SCHWEIZERISCHEN INGENIEUR - UNDARCHITEKTENVHREIN,1996, Empefelung zur Auswal undBewentung von Tunnelvotriebsmachinen.Vol. Spec.
GEHRING K.H., 1995, “Deciding aboutRange of Application for Shield System,Prerequisites,Concepts, Examples”. Attidel la giornata d i studio: “Scavomeccanizzato integrale delle gallerie.Progettazione integrata e criteri di sceltadelle macchine”. Roma.
NATIONAL COAL BOARD (NCB), 1964,“Methods of assessing rock cuttability”,C.E.E. Report, N_ 65 ( 1 ).
NIT - NORWEGIAN INSTITUTE OFTECHNOLOGY, 1988, “Hard rock tunnelboring”. General Report.
NIT - NORWEGIAN INSTITUTE OFTECHNOLOGY, 1990, “Drillabilily, drillingrate index catalogue”, PR 13.90 Universityof Trondheim.
PACHER F., RABCEWICZ L.V., GOLSER J.,1974, Zum derzeitigem Stand derGebirgsklassifizierung in Stollen - undTunnelbau. Preference S 1-8.
AFTESNEW RECOMMENDATIONS ON
CHOOSING MECHANIZED TUNNELLING TECHNIQUES
TEXT PRESENTED BYP. LONGCHAMP, MODERATOR OF AFTES WORK GROUP NO. 4 - TECHNICAL MANAGER, UNDERGROUND WORKS -
BOUYGUES TRAVAUX PUBLICS
WITH THE ASSISTANCE OF A. SCHWENZFEIER, CETU
THESE SUBGROUPS WERE MODERATED BY
J.M. DEMORIEUX, SETEC - F. MAUROY, SYSTRA - J.M. ROGEZ, RATP - J.F. ROUBINET, GTMTHESE RECOMMENDATIONS WERE DRAWN UP BY A NUMBER OF SUB WORK GROUPS WHOSE MEMBERS WERE:
A. AMELOT, SPIE BATIGNOLLES - D. ANDRE, SNCF - A. BALAN, SNCF - H. BEJUI=, AFTES -F. BERTRAND, CHANTIERS MODERNES - F. BORDACHAR, QUILLERY - P. BOUTIGNY, CAMPENON BERNARD SGE -
L. CHANTRON, CETU - D. CUELLAR, SNCF - J.M. FREDET, SIMECSOL - J.L. GIAFFERI, EDF-GDF - J. GUILLAUME, PICO GROUPE RAZEL - P. JOVER, S.M.A.T. - CH. MOLINES, FOUGEROLLES BALLOT -
P. RENAULT, PICO GROUPE RAZEL - Y. RESCAMPS, DESQUENNE ET GIRAL
ACKNOWLEDGEMENTS ARE DUE TO THE FOLLOWING FOR CHECKING THIS DOCUMENT:M. MAREC, MISOA - M.C. MICHEL, OPPBTP - P. BARTHES, AFTES
A.F.T.E.S. will be pleased to receive any suggestions concerning these recommendations
Version 1 - 2000 -approved by the Technical Committee of 23 November 1999 Translated in 2000
INTRODUCTION
The first recommendations on mecha-nized tunnelling techniques issued in1986 essentially concerned hard -
rock machines.The shape of the French market has chan-ged a great deal since then. The deve-lopment of the hydropower sector whichwas first a pioneer, then a big user ofmechanized tunnelling methods has pea-ked and is now declining. In its place, tun-nels now concern a range of generallyurban works, i.e. sewers, metros, roadand rail tunnels.Since most of France’s large urbancentres are built on the flat, and often onrivers, the predominant tunnelling tech-nique has also switched from hard rockto loose or soft ground, often below thewater table.To meet these new requirements, France
has picked up on trends from the east(Germany and Japan).Faced with France’s extremely variedg e o l o g y, project owners, contractors,engineers, and suppliers have adaptedthese foreign techniques to their newconditions at astonishing speed.Now, this new French technical culture isbeing exported throughout the world( G e rm a n y, Egypt, United Kingdom,Australia, China, Italy, Spain, Venezuela,Denmark, Singapore, etc.).This experience forms the basis for theserecommendations, drawn up by a groupof 25 professionals representing the dif-ferent bodies involved.Before the large number of parametersand selection criteria, this group soonrealized that it was not possible to drawup an analytical method for choosing the
most appropriate mechanized tunnellingmethod, but rather that they could pro-vide a document which:
1) clarifies the different techniques, des-cribing and classifying them in differentgroups and categories,
2) analyzes the effect of the selection cri-teria (geological, project, environmentalaspects, etc.),
3) highlights the special features of eachtechnique and indicates its standardscope of application, together with thepossible accompanying measure s . I nother words, these new re c o m m e n d a-tions do not provide ready-made ans-wers, but guide the reader towards a rea-soned choice based on a combination oftechnical factors.
Beaumont machine, 1882. First attempt to drive a tunnel beneath the English Channel. IV-1
IV-2
Choosing mechanized tunnelling techniques
1.PURPOSE OF THESE RECOMMENDATIONS
2. MECHANIZED TUNNELLING TECHNIQUES2.1. Definition and limits2.2. Basic functions
2.2.1. Excavation2.2.2. Support and opposition to hydrostatic pressure2.2.3. Mucking out
2.3. Main risks and advantages of mechanized tunnellingtechniques
3. CLASSIFICATION OF MECHANIZED TUNNELLING TECH-NIQUES
4. DEFINITION OF THE DIFFERENT MECHANIZED TUNNEL-LING TECHNIQUES CLASSIFIED IN CHAPTER 34.1. Machines not providing immediate suppor t4.1.1. General
4.1.2. Boom-type tunnelling machine4.1.3. Main-beam TBM4.1.4. Tunnel reaming machine
4 . 2 . Machines providing immediate support peripherally4.2.1. General4.2.2. Open-face gripper shield TBM4.2.3. Open-face segmental shield TBM4.2.4. Double shield
4.3. Machines providing immediate peripheral and frontalsupport simultaneously
4.3.1. General4.3.2. Mechanical-support TBM4.3.3. Compressed-air TBM4.3.4. Slurry shield TBM4.3.5. Earth pressure balance machine4.3.6. Mixed-face shield TBM
5.EVALUATION OF PARAMETERS FOR CHOICE OF MECHA-NIZED TUNNELLING TECHNIQUES5.1. General5.2. Evaluation of the effect of elementary selection para-meters on the basic functions of mechanized tunnelling tech-niques5.3. Evaluation of the effect of elementary selection para-meters on mechanized tunnelling solutions
6. SPECIFIC FEATURES OF THE DIFFERENT TUNNELLINGTECHNIQUES6.1. Machines providing no immediate support
6.1.1. Specific features of boom-type tunnelling machines6.1.2. Specific features of main-beam TBMs6.1.3. Specific features of tunnel reaming machines
6.2. Specific features of machines providing immediate per-ipheral support
6.2.1. Specific features of open-face gripper shield TBMs
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6.2.2. Specific features of open-face segmental shieldTBMs
6.2.3. Specific features of double shield TBMs6.3. Specific features of TBMs providing immediate frontaland peripheral support
6.3.1. Specific features of mechanical-support shield TBMs6.3.2. Specific features of compressed-air TBMs6.3.3. Specific features of slurry shield TBMs6.3.4. Specific features of earth pressure balance
machines
7. APPLICATION OF MECHANIZED TUNNELLING TECH-NIQUES7.1. Machines not providing immediate support
7.1.1. Boom-type tunnelling machines7.1.2. Main-beam TBMs7.1.3. Tunnel reaming machines
7 . 2 . Machines providing immediate peripheral support7.2.1. Open-face gripper shield TBMs7.2.2. Open-face segmental shield TBMs7.2.3. Open-face double shield TBMs
7.3. Machines providing immediate frontal and peripheralsupport
7.3.1. Mechanical-support shield TBMs7.3.2. Compressed-air TBMs7.3.3. Slurry shield TBMs7.3.4. Earth pressure balance machines
8. TECHNIQUES ACCOMPANYING MECHANIZED TUNNEL-LING8.1. Preliminary investigations from the surface
8.1.1. Environmental impact assessment8.1.2. Ground conditions8.1.3. Resources used
8.2. Forward probing8.3. Ground improvement8.4. Guidance8.5. Additives8.6. Data logging8.7. Tunnel lining and backgrouting
8.7.1. General8.7.2. Lining8.7.3. Backgrouting
9. HEALTH AND SAFETY9.1. Design of tunnel boring machines9.2. Use of TBMs
APPENDIX 1APPENDIX 2APPENDIX 3
1 - PURPOSE OF THESERECOMMENDATIONSThese recommendations supersede the pre-vious version which was issued in 1986 andwhich dealt essentially with hard - rock or“main-beam” tunnel boring machines( T B M s ) .
The scope of this revised version has beenb roadened to include all (or nearly all) typesof tunnelling machines.
The recommendations are intended to serv eas a technical guide for the difficult and ofteni rreversible choice of a tunnel bor ingmachine consistent with the expected geolo-gical and hydrogeological conditions, thee n v i ronment, and the type of the tunnel pro-j e c t .
To start with, the diff e rent kinds of machinesa re classified by group, category, and type.Since all the machines share the commoncharacteristic of excavating tunnels mecha-n i c a l l y, the first criterion for classification isnaturally the machine's ability to pro v i d eimmediate support to the excavation.
This is followed by a list of the parameterswhich should be analyzed in the selectionp rocess, then by details of the extent to whichthese parameters affect mechanized tunnel-ling techniques, and finally a series of fun-damental comments on the diff e rent kinds ofm a c h i n e .
By combining these parameters, decision-makers will arrive at the optimum choice.
The principal specific features of the diff e re n tg roups and categories of techniques are thenoutlined, and the fundamental fields of appli-cation of each category are explained.
L a s t l y, accompanying techniques, which areoften common to several techniques and vitalfor proper operation of the machine, are lis-ted and detailed. It should be noted that datalogging techniques have meant re m a r k a b l ep ro g ress has been made in technical analy-sis of the problems that can be encountere d .
Since health and safety are of constantc o n c e rn in underg round works, a specialchapter is devoted to the matter.
2 - MECHANIZED TUNNEL-LING TECHNIQUES
2.1 - DEFINITION ANDL I M I T S
For the purposes of these re c o m m e n d a t i o n s ,“mechanized tunnelling techniques” (asopposed to the so-called “conventional”techniques) are all the tunnelling techniques
in which excavation is perf o rmed mechani-cally by means of teeth, picks, or discs. Therecommendations there f o re cover all (ornearly all) categories of tunnelling machines,ranging from the simplest (backhoe digger)to the most complicated (confinement-typeshield TBM).
The mechanized shaft sinking techniquesthat are sometimes derived from tunnellingtechniques are not discussed here .
For drawing up tunnelling machine supplycontracts, contractors should refer to therecommendations of AFTES WG 17,“Pratiques contractuelles dans les travauxs o u t e rrains ; contrat de fourn i t u re d’un tun-nelier” (Contract practice for underg ro u n dworks; tunnelling machine supply contract)(TOS No. 150 November/December 1998).
2.2 - BASIC FUNCTIONS
2.2.1 - Excavation
Excavation is the primary function of all theset e c h n i q u e s .
The two basic mechanized excavation tech-niques are :
• Partial-face excavation
• Full-face excavation
With partial-face excavation, the excavationequipment covers the whole sectional are aof the tunnel in a succession of sweeps acro s sthe face.
With full-face excavation, a cutterhead -generally ro t a ry - excavates the entire sec-tional area of the tunnel in a single opera-t i o n .
2.2.2 - Support and opposition tohydrostatic pressure
Tunnel support follows excavation in the hie-r a rchy of classification.
“ S u p p o rt” here means the immediate sup-p o rt provided directly by the machine (wherea p p l i c a b l e ) .
A distinction is made between the techniquesp roviding support only for the tunnel walls,roof, and invert (peripheral support) andthose which also support the tunnel face (per-ipheral and frontal support ) .
T h e re are two types of support: passive andactive. Passive or “open-face” support re a c t spassively against decompression of the sur-rounding ground. Active or “confinement-p re s s u re” support provides active support ofthe excavation.
P e rmanent support is sometimes a direct andintegral part of the mechanized tunnelling
p rocess (segmental lining for instance). Thisaspect has been examined in other AFTESrecommendations and is not discussed fur-ther here .
Recent evolution of mechanized tunnellingtechniques now enables tunnels to be drivenin unstable, permeable, and water- b e a r i n gg round without improving the ground befo-rehand. de ceux-ci.This calls for constantopposition to the hydrostatic pre s s u re andpotential water inflow. Only confinement-p re s s u re techniques meet this re q u i re m e n t .
2.2.3 - Mucking out
Mucking out of spoil from the tunnel itself isnot discussed in these re c o m m e n d a t i o n s .H o w e v e r, it should be recalled that muckingout can be substantially affected by the tun-nelling technique adopted. Inversely, theconstraints associated with mucking opera-tions or spoil treatment sometimes affect thechoice of tunnelling techniques.
The basic mucking-out techniques are :
• haulage by dump truck or similar
• haulage by train
• hydraulic conveyance system
• pumping (less fre q u e n t )
• belt conveyors
2.3 - MAIN RISKS ANDA D VA N TAGES OF MECHANIZED TUNNELLINGT E C H N I Q U E S
The advantages of mechanized tunnellinga re multiple. They are chiefly:
• enhanced health and safety conditions forthe workforce,
• industrialization of the tunnelling pro c e s s ,with ensuing reductions in costs and lead-t i m e s ,
• the possibility some techniques provide ofc rossing complex geological and hydro g e o-logical conditions safely and economically,
• the good quality of the finished pro d u c t( s u rrounding ground less altered, pre c a s tc o n c rete lining segments, etc.)
H o w e v e r, there are still risks associated withmechanized tunnelling, for the choice oftechnique is often irreversible and it is oftenimpossible to change from the technique firstapplied, or only at the cost of immenseupheaval to the design and/or the econo-mics of the pro j e c t .
Detailed analysis of the conditions underwhich the project is to be carried out shouldsubstantially reduce this risk, something for
- Choosing mechanized tunnelling techniques
IV-3
Choosing mechanized tunnelling techniques
which these recommendations will be ofg reat help. The experience and technicalskills of tunnelling machine operators arealso an important factor in the reduction ofr i s k s .
3 - CLASSIFICATION OFMECHANIZED TUNNELLINGTECHNIQUESIt was felt to be vital to have an official clas-sification of mechanized tunnelling tech-niques in order to harmonize the term i n o-logy applied to the most common methods.
The following table presents this classifica-tion. The corresponding definitions are givenin Chapter 4.
The table breaks the classification down intog roups of machines (e.g. boom-type unit) onthe basis of a pre l i m i n a ry division into typesof immediate support (none, peripheral, per-ipheral and frontal) provided by the tunnel-ling technique.
To give more details on the diff e rent tech-niques, the groups are further broken down
into categories and types.
4 - DEFINITION OF THE DIF-FERENT MECHANIZED TUN-NELLING TECHNIQUESCLASSIFIED IN CHAPTER 3
4.1 - MACHINES NOT PROVIDING IMMEDIAT ES U P P O RT
4.1.1 - General
Machines not providing immediate supporta re necessarily those working in ground notrequiring immediate and continuous tunnels u p p o rt .
4.1.2 - Boom-type tunnellingmachine
Boom-type units (sometimes called “tunnelheading machines”) are machines with aselective excavation arm fitted with a tool ofsome sort. They work the face in a series of
sweeps of the arm. Consequently the facesthey excavate can be both varied andvariable. The penetration force of the tools isresisted solely by the weight of the machineLaréaction à.
This group of machines is fitted with one oft h ree types of tool:
• Backhoe, ripper, or hydraulic impact bre a-k e r
• In-line cutterhead (ro a d h e a d e r )
• Transverse cutterhead (ro a d h e a d e r )
AFTES data sheets: No. 8 – 14 (photo 4.1.2)
4.1.3 - Main-beam TBM
A main-beam TBM has a cutterhead thatexcavates the full tunnel face in a single pass.
The thrust on the cutterhead is reacted bybearing pads (or grippers) which pushradially against the rock of the tunnel wall.
The machine advances sequentially, in twop h a s e s :
• Excavation (the gripper unit is stationary )
• Regripping
CLASSIFICATION OF MECHANIZED TUNNELLING TECHNIQUES
IV-4
*For microtunnellers (diameter no greater than 1200 mm), refer to the work of the ISTT.**Machines used in pipe-jacking and pipe-ramming are included in these groups.
Spoil is collected and removed re a rw a rds bythe machine itself.
This type of TBM does not play an active ro l ein immediate tunnel support .
AFTES data sheets: No. 1 to 7, 10 to 13, 15to 24, 26 to 30, 67(photo 4.1.3)
➀ Transverse cutterhead
Boom➁Muck conveyor➂
Loading apron
Crawler chassis
➃➄
Phot o 4 .1 .2 - RoadheaderSchéma 4.1 .2
➀➁
➃ ➄
Phot o 4.1 .4 - Sauges t unnel (Swit zerland)
- Choosing mechanized tunnelling techniques
IV-5
4.1.4 - Tunnel reaming machine
A tunnel reaming machine has the same basic functions asa main-beam TBM. It bores the final section from an axialtunnel (pilot bore) from which it pulls itself forw a rd bymeans of a gripper unit.
➀ Pilot bore
gripper unit (traction)➁
➁
Cutterhead➂Rear support
Muck conveyor➃➃➄
➄
Phot o 4 .1 .3 - Lesot ho Highlands Wat er Project
▼
▼
➂
➀ ➁➂ ➃
➄
➀ Canopy/Hood/Roof
Rear gripper➁Front gripper➂Muck conveyor
Rear lift leg➃➄
➀➂
Choosing mechanized tunnelling techniques
4.2 - MACHINES PROVI -DING IMMEDIATE PERIPHE -R A L S U P P O RT
4.2.1 - General
Machines providing immediate peripherals u p p o rt only belong to the open-face TBMg ro u p .
While they excavate they also support the
sides of the tunnel. The tunnel face is not sup-p o rted. d’aucune façon.
They can have two types of shield:
• one-can shield,
• shield of two or more cans connected bya rt i c u l a t i o n s .
The diff e rent configurations for peripheral-s u p p o rt TBMs are detailed below.
4.2.2 - Open-face gripper shieldTBM
A gripper shield TBM corresponds to the defi-nition given in § 4.1.32 except that it ismounted inside a cylindrical shield incorpo-rating grippers.
The shield provides immediate passive per-ipheral support to the tunnel walls.
AFTES data sheet: N° 25
IV-6
Phot o 4 .2.2 - Main CERN t unnel
➀ Cutterhead
Muck extraction conveyor➁ ➅ Muck transfer conveyor
Motor➆Segment erector➇
Télescopic section➂Thrust ram
Grippers (radial thrust)
➃
➄
4.2.3 - Open-face segmentalshield TBM
An open-face segmental shield TBM is fittedwith either a full-face cutterhead or an exca-vator arm like those of the diff e rent boom-
type units. To advance and tunnel, the TBM'slongitudinal thrust rams react against thetunnel lining erected behind it by a speciale rector incorporated into the TBM.
AFTES data sheets: No. 31 - 32 - 41 - 66
▼
a Cutterhead
Shieldb
f Muck extraction conveyor
Muck transfer conveyorgGathering armh
ij Motor
Tailskin articulation (option)kThrust ringl
Muck hopperArticulation (option)cThrust ram
Segment erector
de
Phot o 4 .2 .3Athens met ro
▼
4.2.4 - Double shield
A double shield is a TBM with a full-face cut-t e rhead and two sets of thrust rams that re a c tagainst either the tunnel walls (radial grip-pers) or the tunnel lining. The thrust method
used at any time depends on the type ofg round encountered. With longitudinalt h rust, segmental lining must be installedbehind the machine as it advances.
The TBM has three or more cans connected
by articulations and a telescopic central unitwhich relays thrust from the gripping/thru s-ting system used at the time to the front of theT B M .
AFTES data sheets: No. 65 – 68 – 71
- Choosing mechanized tunnelling techniques
IV-7
▼
a Cutterheadb Front canc Telescopic sectiond Gripper unite Tailskinf Main thrust rams
g Longitudinal thrust ramsh Grippersi Tailskin articulation (option)j Segment erectork Muck extraction conveyorl Muck transfer conveyor
Phot o 4 .2 .4 - Salazie wat er t ransfer project(Reunion Island)
4.3 - MACHINES PROVI -D I N G I M M E D I ATE PERIPHE -RAL AND FRONTAL SUP -P O RT SIMULTA N E O U S LY
4.3.1 - General
The TBMs that provide immediate peripheraland frontal support simultaneously belong tothe closed-faced gro u p .
They excavate and support both the tunnelwalls and the face at the same time.
Except for mechanical-support TBMs, they all
have what is called a cutterhead chamber atthe front, isolated from the re a rw a rd part ofthe machine by a bulkhead, in which a confi-nement pre s s u re is maintained in order toactively support the excavation and/orbalance the hydrostatic pre s s u re of theg ro u n d w a t e r.
The face is excavated by a cutterhead wor-king in the chamber.
The TBM is jacked forw a rd by rams pushingo ff the segmental lining erected inside theTBM tailskin, using an erector integrated intothe machine.
4.3.2 - Mechanical-support TBM
A mechanical-support TBM has a full-facec u t t e rhead which provides face support byconstantly pushing the excavated materialahead of the cutterhead against the sur-rounding gro u n d .
Muck is extracted by means of openings onthe cutterhead fitted with adjustable gatesthat are controlled in real time.
AFTES data sheets: No. 38 – 39 – 40 – 51 –58 – 64
a Cutterheadb Shieldc Articulation (option)d Thrust rame Segment erectorf Muck extraction conveyor
g Muck transfer conveyorh Muck hopper (with optional gate)i Cutterhead drive motorj Gated cutterhead openingsk Peripheral seal between cutterhead and shieldl Tailskin articulation (option)
▼
Phot o 4.3 .2 RER Line D (Pa ris)
Choosing mechanized tunnelling techniques
4.3.3 - Compressed-air TBM
A compressed-air TBM can have either a full-face cutterhead or excavating arms like thoseof t he d i f f e r en t boom-type uni t s .Confinement is achieved by pressurizing theair in the cutting chamber.
Muck is extracted continuously or interm i t-tently by a pre s s u re - relief discharge systemthat takes the material from the confinementp re s s u re to the ambient pre s s u re in the tun-n e l .
AFTES data sheets: No. 37 – 42 – 43 – 53 –54 – 70
IV-8
a Excavating armb Shieldc Cutting chamberd Airtight bulkheade Thrust ramf Articulation (option)
g Tailskin sealh Airlock to cutting chamberi Segment erectorj Screw conveyor (or conveyor and gate)k Muck transfer conveyor Phot o 4 .3.3 - Compressed air TBM - Boom type
4.3.4 - Slurry shield TBM
A slurry shield TBM has a full-face cutte-rhead. Confinement is achieved by pre s s u r i-zing boring fluid inside the cutterhead cham-b e r. Circulation of the fluid in the chamberflushes out the muck, with a regular pre s s u rebeing maintained by directly or indire c t l yc o n t rolling discharge rates.
AFTES data sheets:No. 33 – 34 – 35 – 36 –44 – 50 – 52 – 56 – 57 -60 – 62 – 63 – 69 – 76 –C a i ro – Sydney
▼
a Cutterheadb Shieldc Air bubbled Watertight bulkheade Airlock to cutterhead chamber
f Tailskin articulation (option)
g Thrust ramh Segment erectori Tailskin seal
j Cutterhead chamberk Agitator (option)l Slurry supply line
m Slurry return linePhoto 4 .3 .4 - Cairo met ro
a b c d e f g
h i j ke
▼
4.3.5 - Earth pressure balancemachine
An earth pre s s u re balance machine (EPBM)has a full-face cutterhead. Confinement isachieved by pressurizing the excavatedmaterial in the cutterhead chamber. Muck isextracted from the chamber continuously or
i n t e rmittently by a pre s s u re - relief discharg esystem that takes it from the confinementp re s s u re to the ambient pre s s u re in the tun-n e l .
EPBMs can also operate in open mode orwith compressed-air confinement if speciallye q u i p p e d .
AFTES data sheets: No. 45 – 46 - 47 – 48 –49 – 55 – 59 – 61 – 72 – 73 – 74* - 77 to8 5
*TBMs also working with compre s s e d - a i rc o n f i n e m e n t
- Choosing mechanized tunnelling techniques
IV-9
a Cutterheadb Shieldc Cutterhead chamberd Airtighte Thrust ram
f Articulation (option)g Tailskin sealh Airlock to cutterheau chamberi Segment erector
j Screw conveyork Muck transfer conveyor
▼
Phot o 4.3 .5 - CaluireTunnel, Lyons (France)
4.3.6 - Mixed-face shield TBM
Mixed-face shield TBMs have full-face cutte-rheads and can work in closed or open modeand with diff e rent confinement techniques.
Changeover from one work mode to anotherre q u i res mechanical intervention to changethe machine configuration.
D i ff e rent means of muck extraction are usedfor each work mode.
T h e re are three main categories of machine:
• Machines capable of working in open
mode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with earth pre s s u re balanceconfinement provided by a screw conveyor;
• Machines capable of working in openmode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with slurry confinement pro-vided by means of a hydraulic mucking outsystem (after isolation of the belt conveyor);
• Machines capable of providing earth pre s-s u re balance and slurry confinement.
TBMs of this type are generally restricted tol a rge-diameter bores because of the spacere q u i red for the special equipment re q u i re dfor each confinement method.
AFTES data sheets: A86 Ouest (Socatop),Madrid metro packages 2 & 4, KCR 320(Hong Kong)
Phot o 4.3 .6b - A86 Ouest t unnel (Socat op) Madrid met ro
Phot o 4 .3.6aA86 Oues t unnel (Socat op)
Choosing mechanized tunnelling techniques
5 - EVALUATION OF PARA-METERS FOR CHOICE OFMECHANIZED TUNNELLINGTECHNIQUES
5 . 1 .G E N E R A L
It was felt useful to assess the degree to whiche l e m e n t a ry parameters of all kinds affect thedecision-making process for choosing bet-ween the diff e rent mechanized tunnellingt e c h n i q u e s .
The objectives of this evaluation are :
• to rank the importance of the elementaryselection parameters, with some indicationof the basic functions concern e d .
• to enable project designers envisaging amechanized tunnelling solution to check thatall the factors affecting the choice have beene x a m i n e d .
• to enable contractors taking on constru c-tion of a project for which mechanized tun-nelling is envisaged to check that they are inpossession of all the relevant information ino rder to validate the solution chosen.
This evaluation is presented in the form of twotables (Tables 1 and 2).
Table 1 (§ 5.2.) indicates the degree to whicheach of the elementary selection parametersa ffects each of the basic functions of mecha-nized tunnelling techniques (all techniquesc o m b i n e d ) .
Table 2 (§ 5.3) indicates the degree to which
each of the elementary selection parametersa ffects each individual mechanized tunnel-ling technique.
These evaluation tables are complementedby comments in the appendix.
The list of parameters is based on that drawnup by AFTES recommendations work gro u pNo. 7 in its very useful document "Choix desp a r a m è t res et essais géotechniques utiles àla conception, au dimensionnement et àl'exécution des ouvrages creusés en souter-rain" (Choice of geotechnical parametersand tests of relevance to the design andc o n s t ruction of underg round works). This ini-tial list has been complemented by factorsother than geotechnical ones.
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Basic funct ion SUPPORT OPPOSITION TOEXCAVATION
MUCKING OUT,Element ary
Front al PeriphericalHYDROSTATIC EXTRACTION,
paramet ers PRESSURE TRANSPORTSTOCKPILING
A B C D E
1. NATURAL CONTRAINTS 2 2 SO 1 0
2. PHYSICAL PARAMETERS 2.1 Ident ificat ion 2 1 2 2 12.2 Global appreciat ion of qualit y 2 2 0 1 02.3 Discont inuit ies 2 2 2 1 02.4 Alt erabilit y 1 1 SO 1 12.5 Wat er chemist ry 1 0 SO 0 1
3. MECHANICAL PARAMETERS3.1 St rengt h Soft ground 2 2 SO 1 0
Hard rock 1 1 SO 2 03.2 Deformabilit y 2 2 SO 0 03.3 Liquefact ion pot ent ial 0 0 0 0 0
4. HYDROGEOLOGICAL PARAMETERS 2 2 2 1 0
5. OTHER PARAMETERS5.1 Abrasiveness - Hardness 0 0 0 2 15.2 Propensit y t o st ick 0 0 0 2 25.3 Ground/ machine f rict ion 0 1 0 0 05.4 Présence of gas 0 0 0 0 0
6. PROJECT CHARACTERISTICS6.1 Dimensions, shape 2 2 2 1 26.2 Vert ical alignment 0 0 0 0 26.3 Horizont al alignment 0 0 0 0 16.4 Environment
6.4.1 Sensit ivit y t o set t lement 2 2 2 0 06.4.2 Sensit ivit y to disturbance and work const raint s 0 0 0 0 2
6.5 Anomalies in ground6.5.1 Het erogeneit y of ground in t unnel sect ion 1 1 0 2 06.5.2 Nat ural/ art if icial obst acles 0 0 0 1 06.5.3 Voids 2 2 2 0 0
2 : Decisiv e 1 : Has ef f ect 0 : No ef f ect SO: Not appl icable
See comment s on t his t able in Appendix 1
5.2 - EVALUATION OF THE EFFECT OF ELEMENTARY SELECTION PARAMETERS ON THEBASIC FUNCTIONS OF MECHANIZED TUNNELLING TECHNIQUES
Table 1
Choosing mechanized tunnelling techniques
6 - SPECIFIC FEATURES OFTHE DIFFERENT TUNNEL-LING TECHNIQUES
6.1 - MACHINES PROVI -DING NO IMMEDIATE SUP -P O RT
6.1.1 - Specific features of boom-type tunnelling machines
a) GeneralBoom-type tunnelling machines are gene-rally suited to highly cohesive soils and softrock. They consist of an excavating arm orboom mounted on a self-propelling chassis.T h e re is no direct relationship between themachine and the shape of the tunnel to bedriven; the tunnel cross-sections excavatedcan be varied and variable. The face can beaccessed directly at all times. Since thesemachines react directly against the tunnelf l o o r, the floor must have a certain bearingc a p a c i t y.
b) ExcavationThe arms or booms of these machines aregenerally fitted with a cutting or milling headwhich excavates the face in a series ofsweeps. These machines are called ro a d-headers. The maximum thrust on the ro a d-header cutterhead is directly related to themass of the machine. The cutters work eithertransversally (perpendicular to the boom) orin-line (axially, about the boom axis). In mostcases the spoil falling from the face is gathe-red by a loading apron fitted to the front ofthe machine and transported to the back ofthe machine by belt conveyor. This excava-tion method generates a lot of dust which hasto be controlled (extraction, water spray, fil-tering, etc.).
In some cases the cutterhead can be re p l a-ced by a backhoe bucket, ripper, or hydrau-lic impact bre a k e r.
c) Support and opposition to hydro s t a -tic pre s s u reT h e re is no tunnel support associated withthis type of machine. It must be accompaniedby a support method consistent with theshape of the tunnel and the ground condi-tions encountered (steel ribs, rockbolts, shot-c rete, etc.).
This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary.
d) Mucking outMucking out can be associated with this kind
of machine or handled separately. It can bedone directly from the face.
6.1.2 - Specific features of main-beam TBMs
a) GeneralThe thrust at the cutterhead is reacted to oneor two rows of radial thrust pads or gripperswhich take purchase directly on the tunnelwalls. As with shield TBMs, a trailing backupbehind the machine carries all the equipmentit needs to operate and the associated logis-tics. Forw a rd probe drilling equipment isgenerally fitted to this type of TBM. The facecan be accessed by retracting the cutterh e a df rom the face when the TBM is stopped.
The machine advances sequentially (bore ,regrip, bore again).
b) ExcavationThese full-face TBMs generally have a ro t a ryc u t t e rhead dressed with diff e rent cutters (disccutters, drag bits, etc.). Muck is generallyremoved by a series of scrapers and a buc-ket chain which delivers it onto a conveyort r a n s f e rring it to the back of the machine.Water spray is generally re q u i red at the faceboth to keep dust down and to limit the tem-p e r a t u re rise of the cutters.
c) Support and opposition to hydro s t a -tic pre s s u reTunnel support is independent of the machine(steel ribs, rockbolts, shotcrete, etc.) but canbe erected by auxiliary equipment mountedon the beam and/or backup. If support ise rected from the main beam, it must takeaccount of TBM movement and the gripperadvance stroke. The cutterhead is not gene-rally designed to hold up the face. A canopyor full can is sometimes provided to pro t e c toperators from falling blocks.
This kind of TBM cannot oppose hydro s t a t i cp re s s u re . Accompanying measu re s( g roundwater lowering, drainage, gro u n di m p rovement, etc.) are re q u i red if the expec-ted pre s s u res or inflows are high.
d) Mucking out Mucking out is generally done with wagonsor by belt conveyor. It is directly linked to theTBM advance cycle.
6 . 1 . 3 . Specific features of tunnelreaming machines
a) GeneralTunnel reaming machines work in much thesame way as main-beam TBMs, except thatthe cutterhead is pulled rather than pushed.This is done by a traction unit with grippersin a pilot bore. As with all main-beam andshield machines, the cutterhead is rotated by
a series of hydraulic or electric motors. Thetunnel can be reamed in a single pass with asingle cutterhead or in several passes withc u t t e rheads of increasing diameter.
b) ExcavationSee Chapter 6.1.2 § b) (main-beam TBM).
c) Support and opposition to hydro s t atic pre s s u re The support in the pilot bore must be des-t ructible (glass-fibre rockbolts) or re m o v a b l e(steel ribs) so that the cutterhead is not dama-ged. The final support is independent of thereaming machine, but can be erected fro mits backup.
For details on opposition to the hydro s t a t i cp re s s u re, see Chapter 6.1.2 § c (main-beamT B M ) .
d) Mucking outSee Chapter 6.1.2.§ d) (main-beam TBM).
6.2 - SPECIFIC FEATURES OFMACHINES PROVIDINGI M M E D I ATE PERIPHERALS U P P O RT
6.2.1 - Specific features of open-face gripper shield TBMs
a) GeneralAn open-face gripper shield TBM is the sameas a main-beam TBM except that it has acylindrical shield.
The thrust of the cutterhead is reacted againstthe tunnel walls by means of radial pads (orgrippers) taking purchase through openingsin the shield or immediately behind it. As withother TBM types, a backup trailing behindthe TBM carries all the equipment it needs tooperate, together with the associated logis-tics.
The TBM does not thrust against the tunnellining or support .
b) ExcavationSee Chapter 6.1.2 § b) (main-beam TBM).
c) Support and opposition to hydro s t atic pre s s u reThe TBM provides immediate passive per-ipheral support. It also protects workers fro mthe risk of falling blocks. If permanent tunnels u p p o rt is re q u i red, it consists either of seg-ments (installed by an erector on the TBM) orof support erected independently.
This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terr a i n .
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d) Mucking outSee Chapter 6.1.2 § d) (main-beam TBM) .
6.2.2 - Specific features of open-face segmental shield TBMs
a) GeneralAn open-face shield segmental TBM haseither a full-face cutterhead or an excavatinga rm like those of the diff e rent boom-type tun-nelling machines. The TBM is thrust forw a rdby rams reacting longitudinally against thetunnel lining erected behind it.
b) ExcavationTBM advance is generally sequential:
1) boring under thrust from longitudinalrams reacting against the tunnel lining
2) retraction of thrust rams and erection ofnew ring of lining.
c) Support and opposition to hydro s t a -tic pre s s u reThe TBM provides passive peripheral sup-p o rt and also protects workers from the riskof falling blocks.
The tunnel face must be self-supporting. Evena full-face cutterhead can only hold up theface under exceptional conditions (e.g. limi-tation of collapse when the TBM is stopped).
Te m p o r a ry or final lining is erected behindthe TBM by an erector mounted on it. It isagainst this lining that the rams thrust to pushthe machine forw a rd.
This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terr a i n .
d) Mucking outMuck is generally removed by mine cars orbelt conveyors. Mucking out is directly linkedto the TBM advance cycle.
6.2.3 - Specific features of doubleshield TBMs
Double shield TBMs combine radial pur-chase by means of grippers with longitudi-nal purchase by means of thrust rams re a c-ting against the lining. A telescopic sectionat the centre of the TBM makes it possible forexcavation to continue while lining segmentsa re being erected.
Excavation proceeds as follows: with the re a rsection of the TBM secured by the grippers,the front section thrusts against it by meansof the main rams between the two sections,and tunnels forw a rd. A ring of segmentallining segments is erected at the same time.The grippers are then released and the lon-
gitudinal rams thrust against the tunnel liningto shove the rear section forw a rd. The re a rsection regrips and the cycle is repeated.
6.3 - SPECIFIC FEATURES OFTBMS PROVIDING IMME -D I ATE FRONTAL AND PER -IPHERAL SUPPORT
6.3.1 - Specific features of mecha-nical-support shield TBMs
a) GeneralM e c h a n i c a l - s u p p o rt shield TBMs ensure thestability of the excavation by retaining exca-vated material ahead of the cutterhead. Thisis done by partially closing gates on ope-nings in the head.
b) ExcavationThe face is excavated by a full-face cutte-rh e a d .
c) Support and opposition to hydro s t a -tic pre s s u reReal-time adjustment of the openings in thec u t t e rhead holds spoil against the face.
F rontal support is achieved by holding spoilagainst the face (in front of the cutterh e a d ) .
The shield provides immediate passive per-ipheral support .
The tunnel lining is ere c t e d :• either inside the TBM tailskin, in which caseit is sealed against the tailskin (tail seal) andback grout is injected into the annular spacea round it,• or behind the TBM tailskin (expandedlining, segments with pea-gravel backfill andg rout).
This type of machine cannot oppose hydro-static pre s s u re as a rule, so accompanyingm e a s u res (ground improvement, gro u n d w a-ter lowering, etc.) may be necessary whenworking in water-bearing or unstable ter-r a i n .
d) Mucking outMucking out is generally by means of minecars or belt conveyors.
6.3.2 - Specific features of com-pressed-air TBMs
a) GeneralWith compressed-air TBMs, only pre s s u r i-zation of the air in the cutter chamberopposes the hydrostatic pre s s u re at the face.
C o m p ressed-air confinement pre s s u re ispractically uniform over the full height of theface. On the other hand, the pre s s u re dia-
gram for thrust due to water and ground atthe face is trapezoidal. This means there ared i ff e rences in the balancing of pre s s u res atthe face. The solution generally adoptedinvolves compressing the air to balance thewater pre s s u re at the lowest point of the face.The greater the diameter, the greater theresulting pre s s u re diff e rential; for this re a s o nthe use of compressed-air confinement inl a rge-diameter tunnels must be studied verya t t e n t i v e l y.
C o m p ressed-air TBMs are generally usedwith moderate hydrostatic pre s s u res (lessthan 0.1 MPa).
b) ExcavationThe face can be excavated by a variety ofequipment (from diggers to full-face cutte-rheads dressed with an array of tools). In thecase of rotating cutterheads, the size of thespoil discharged is controlled by the ope-nings in the cutterheadla ro u e .
Muck can be extracted from the face by as c rew conveyor (low hydrostatic pre s s u re) orby an enclosed conveyor with an airlock.
c) Support and opposition to hydro s t a -tic pre s s u reMechanical immediate support of the tunnelface and walls excavation is provided by thec u t t e rhead and shield re s p e c t i v e l y.
The hydrostatic pre s s u re in the ground isopposed by compressed air.
d) Mucking outMuck is generally removed by conveyor orby wheeled vehicles (trains, trucks, etc.).
6.3.3 - Specific features of slurryshield TBMs
a) GeneralThe principle of slurry shield TBM operationis that the tunnel excavation is held up bymeans of a pressurized slurry in the cutte-rhead. The slurry entrains spoil which isremoved through the slurry re t u rn line.
The tunnel lining is erected inside the TBMtailskin where a special seal (tailskin seal)p revents leakage.
Back grout is injected behind the lining as theTBM advances.
b) ExcavationThe face is excavated by a full-face cutte-rhead dressed with an array of cutter tools.Openings in the cutterhead (plus possibly ac rusher upline of the first slurry re t u rn linesuction pump) control the size of spoil re m o-ved before it reaches the pumps.
- Choosing mechanized tunnelling techniques
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Choosing mechanized tunnelling techniques
c) Support and opposition to hydro s t a -tic pre s s u reF rontal and peripheral support of the tunnelexcavation are the same, i.e. by means of thes l u rry pre s s u re generated by the hydraulicmucking out system.
In permeable ground (K ≥ 5 x 10-5 m/s) it ispossible to pressurize the chamber by cre a-ting a ‘cake’ of thixotropic slurry (bentonite,p o l y m e r, etc.), generally with relative densityof between 1.05 and 1.15, on a tunnel faceand walls.
With such a ‘cake’ in place it is possible forworkers to enter the pressurized cutterh e a d(via an airlock).
The TBM can be converted to open mode, butthe task is complex.
As for tunnel support, the hydrostatic pre s-s u re is withstood by forming a ‘cake’ to helpf o rm a hydraulic gradient between theh y d rostatic pre s s u re in the ground and thes l u rry pre s s u re in the cutterhead chamber.
Together with control of the stability of theexcavation and of settlement, opposition toh y d rostatic pre s s u re is a design considera-tion for the confinement pre s s u re; the confi-nement pre s s u re is regulated either by dire c tadjustment of the slurry supply and re t u rnpumps or by means of an “air bubble” whoselevel and pre s s u re are controlled by a com-p ressor and relief valves. With an “airbubble” in the cutterhead chamber the confi-nement pre s s u re can be measured and re g u-lated within a very narrow range of varia-t i o n .
d) Mucking outMuck is removed by pumping it through thepipes connecting the TBM to the slurry sepa-ration and recycling plant.
In most cases the muck is often treated out-side the tunnel, in a slurry separation plant.This does introduce some risks associatedwith the type of spoil to be treated (cloggingof plant, difficulties for disposal of re s i d u a ls l u d g e ) .
The pump flowrate and the treatment capa-city of the separation plant determine TBMp ro g re s s .
6.3.4 - Specific features of earthpressure balance machines
a) General The principle of EPBM operation is that theexcavation is held up by pressurizing thespoil held in the cutterhead chamber tobalance the earth pre s s u re exerted. If neces-s a ry, the bulked spoil can be made moreplastic by injecting additives from the ope-nings in the cutterhead chamber, the pre s-
s u re bulkhead, and the muck-extractions c rew conveyor. By reducing friction, theadditives reduce the torque re q u i red to churnthe spoil, thus liberating more torque to workon the face. They also help maintain aconstant confinement pre s s u re at the face.
Muck is extracted by a screw conveyor, pos-sibly together with other pre s s u re - re l i e fd e v i c e s .
The tunnel lining is erected inside the TBMtailskin, with a tailskin seal ensuring there areno leaks. Back grout is injected behind thelining as the TBM advances.
b) ExcavationThe tunnel is excavated by a full-face cutte-rhead dressed with an array of tools. The sizeof spoil removed is controlled by openings inthe cutterhead which are in turn determ i n e dby the dimensional capacity of the scre wc o n v e y o r.
The power at the cutterhead has to be highbecause spoil is constantly churned in thec u t t e rhead chamber.
c) Support and opposition to hydro s t a -tic pre s s u reFace support is uniform. It is obtained bymeans of the excavated spoil and additiveswhich generally maintain its relative densityat between 1 and 2. Peripheral support canbe enhanced by injecting products thro u g hthe shield.
For manual work to proceed in the cutte-rhead chamber, it may be necessary toc reate a sealing cake at the face thro u g hc o n t rolled substitution (without loss of confi-nement pre s s u re) of the spoil in the chamberwith bentonite slurry.
L’ a rc h i t e c t u re de ce type de tunnelier perm e tun passage rapide du mode fermé en modeo u v e rt .
The hydrostatic pre s s u re is withstood by for-ming a plug of confined earth in the cham-ber and screw conveyor; the pre s s u re gra-dient between the face and the spoild i s c h a rge point is balanced by pre s s u relosses in the extraction and pre s s u re - re l i e fd e v i c e .
C a re must be take over the type and locationof sensors in order to achieve proper mea-s u rement and control of the pre s s u re in thec u t t e rhead chamber.
d) Mucking outAfter the muck-extraction screw conveyor,spoil is generally transported by conveyorsor by wheeled vehicles (trains, tru c k s ) .
The muck is generally “diggable”, enablingit to be disposed of without additional tre a t-ment; however, it may be necessary to study
the biodegradability of the additives if thedisposal site is in a sensitive enviro n m e n t .
The arc h i t e c t u re of this type of TBM allows forrapid changeover from closed to open modeand vice versa.
7 - APPLICATION OFMECHANIZED TUNNELLINGTECHNIQUES
7.1 - MACHINES NOT PRO -VIDING IMMEDIATE SUP -P O RT
7.1.1 - Boom-type tunnellingmachines
Boom-type units are generally suitable forhighly cohesive soils and soft rock. Theyreach their limits in soils with compre s s i v es t rength in excess of 30 to 40 MPa, whichc o rresponds to class R3 to R5 in the classifi-cation given in Appendix 3 (depending onthe degree of cracking or foliation). Thee ffective power of these machines is dire c t l yrelated to their weight.
When these machines are used in water-bearing ground, some form of gro u n di m p rovement must be carried out before-hand to overcome the problem of significantwater inflow.
When excavating clayey soils in water, thecutters of roadheaders may become cloggedor balled; in such terrain, a special study ofthe cutters must carried out to overcome thep roblem. It may be advisable to use a back-hoe instead.
These techniques are particularly suitable forexcavating tunnels with short lengths of dif-f e rent cross-sections, or where the tunnel isto be driven in successive headings.
The tunnel support accompanying thismethod of excavation is independent of themachine used. It will be adapted to the condi-tions encountered (ground, enviro n m e n t ,etc.) and the shape of the excavation.
7.1.2 - Main-beam TBMs
Main-beam TBMs are particularly suited totunnels of constant cross-section in rock ofs t rength classes R1 to R4 (see rock classifi-cation in Appendix 3).
For the lower strength classes (R3b-R4), thebearing surface of the grippers is generallyi n c reased in order to prevent them punchinginto the ground. If there is a risk of alterationof the tunnel floor due to water, laying ac o n c rete invert behind the machine will faci-
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litate movement of the backup. To pro v i d es h o rt - t e rm stabilization of the excavation, itwill be necessary to have rapid support - e re c-tion systems that will be independent of butn e v e rtheless compatible with the TBM.
For the higher strength classes (R1-R2a), allthe boreability parameters must be taken intoaccount in the TBM design.
In hard and abrasive ground in part i c u l a r, itis recommended that every precaution betaken to allow for cutters to be replaced inp e rfect safety.
A system for spraying water on the tunnelface will cool the cutters and keep dust down.It can be complemented by dust scre e n s ,extraction, and filters.
Main-beam TBMs are generally fitted withd e s t ructive drilling rigs for forw a rd pro b edrilling, together with drill data-loggingequipment. The probe holes are drilled whenthe TBM is not working.
The design of these machines does not allowthem to support non-cohesive soils as theyadvance, or to oppose hydrostatic pre s s u re .For this reason accompanying measure ssuch as drainage and/or consolidation ofthe ground are necessary before themachines traverse a geological accident.Consequently the TBM must be equipped todetect such features and to treat the gro u n dahead of the face when necessary.
7.1.3 - Tunnel reaming machines
Tunnel reamers are suitable for excavatingl a rge horizontal or inclined tunnels (upward sof 8 m in diameter) in rock (R1 to R3, some-times R4 and R5).
The advantages of reaming a tunnel from apilot bore are as follows:
• The ground is investigated as the pilot boreis driven
• Any low-strength ground encountered canbe consolidated from the pilot bore beforefull-diameter excavation
• The ground to be excavated is drained
• The pilot bore can be used for dewateringand ventilation
• Te m p o r a ry support can be erected inde-pendently of the machine.
7.2 - MACHINES PROVI -DING IMMEDIATE PERIPHE -RAL SUPPORT
7.2.1 - Open-face gripper shieldTBMs
Open-face gripper shield TBMs are part i c u-larly suitable for tunnelling in rock of stre n g t hclasses between R1 and R3
The shield provides immediate support forthe tunnel and/or protects the workforc ef rom falling blocks.
The shield can help get through certain geo-logical difficulties by avoiding the need fors u p p o rt immediately behind the cutterh e a d .
Application of this technique can be limitedby the ability of the ground to withstand theradial gripper thru s t .
The general considerations outlined in §7.1.2 also apply here .
7.2.2 - Open-face segmentalshield TBMs
An open-face segmental shield TBM re q u i re sfull lining or support along the length of thetunnel against which it can thrust to advance.
Its field of application is soft rock (stre n g t hclasses R4 and R5) and soft ground re q u i r i n gs u p p o rt but in which the tunnel face holds up.
The general considerations outlined in §7.1.2 also apply here .
This type of TBM can traverse certain typesof heterogeneity in the ground. It alsoenables the tunnel support to be industriali-zed to some extent. On the other hand, thep resence of the lining and shield can give riseto difficulties when crossing obstacles suchas geological accidents, since they hinderaccess to the face for treatment or consoli-dation of the gro u n d .
7.2.3 - Open-face double shieldTBMs
Open-face double shield TBMs combine theadvantages and disadvantages associatedwith radial grippers and longitudinal thru s trams pushing off tunnel lining: they needeither a lining or ground of sufficient stre n g t hto withstand gripper thru s t .
This greater technical complexity is some-times chosen when lining is re q u i red so thatboring can proceed (with gripper purc h a s e )while the lining ring is being ere c t e d .
7.3 - MACHINES PROVI -DING IMMEDIATE FRONTA LAND PERIPHERAL SUPPORT
7.3.1 - Mechanical-support shieldTBMs
The diff e rence between mechanical-supportshield TBMs and open-face segmental shieldTBMs lies in the nature of the cutterh e a d .M e c h a n i c a l - s u p p o rt TBMs have:
• openings with adjustable gates
• a peripheral seal between the cutterh e a dand the shield.
Face support is achieved by holding spoilahead of the cutterhead by adjusting theopenings. It does not provide ‘genuine’confinement, merely passive support of thef a c e .
Its specific field of application is there f o re insoft rock and consolidated soft ground withlittle or no water pre s s u re
7.3.2 - Compressed-air TBMs
C o m p ressed-air TBMs are particularly sui-table for ground of low permeability with nomajor discontinuities (i.e. no risk of suddenloss of air pre s s u re ) .
The ground tunnelled must necessarily havean impermeable layer in the overburd e n .
C o m p ressed-air TBMs tend to be used toexcavate small-diameter tunnels.
Their use is not recommended in circ u m-stances where the ground at the face is hete-rogeneous (unstable ground in the ro o fwhich could cave in). They should be pro h i-bited in organic soil where there is a risk off i re .
In the case of small-diameter tunnels, it maybe possible to have compressed air in all orp a rt of the finished tunnel.
7.3.3 - Slurry shield TBMs
S l u rry shield TBMs are particularly suitablefor use in granular soil (sand, gravel, etc.)and heterogeneous soft ground, though theycan also be used in other terrain, even if itincludes hard - rock sections.
T h e re might be clogging and difficulty sepa-rating the spoil from the slurry if there is clayin the soil.
These TBMs can be used in ground with highp e rmeability (up to 10-2 m/s), but if there ishigh water pre s s u re a special slurry has tobe used to form a watertight cake on theexcavation walls. However, their use isusually restricted to hydrostatic pre s s u res ofa few dozen MPa.
- Choosing mechanized tunnelling techniques
IV-15
Choosing mechanized tunnelling techniques
Generally speaking, good control of slurryquality and of the regularity of confinementp re s s u re ensures that surface settlement iskept to the very minimum.
Contaminated ground (or highly aggre s s i v ewater) may cause problems and re q u i re spe-cial adaptation of the slurry mix design.
The presence of methane in the ground is nota problem for this kind of TBM.
If the tunnel alignment runs through contras-ting heterogeneous ground, there may bed i fficulties extracting and processing thes p o i l .
7.3.4 - Earth pressure balancemachines
EPBMs are particularly suitable for soilswhich, after churning, are likely to be of aconsistency capable of transmitting the pre s-s u re in the cutterhead chamber and form i n ga plug in the muck-extraction screw conveyor(clayey soil, silt, fine clayey sand, soft chalk,marl, clayey schist).
They can handle ground of quite high per-meability (10–3 to 10-4 m/s), and are alsocapable of working in ground with occasio-nal discontinuities requiring localized confi-nement.en l’absence
In hard and abrasive ground it may ben e c e s s a ry to use additives or to take specialm e a s u res such as installing hard-facing orwearplates on the cutterhead and scre wc o n v e y o r.a vitesse de pro g ression de l’usurepar
In permeable ground, maintenance in thec u t t e rhead chamber is made complexbecause of the need to establish a watert i g h tcake at the face beforehand, without losingconfinement pre s s u re .
8 - TECHNIQUES ACCOMPA-NYING MECHANIZED TUN-NELLING
8.1 - PRELIMINARY INVES -T I G ATIONS FROM THE SUR -FA C E
8.1.1 - Environmental impactassessment
At the pre l i m i n a ry design stage an enviro n-mental impact assessment should be carr i e dout in order to properly assess the dimensio-nal characteristics proposed for the tunnel,p a rticularly its cross-section, sectional are a ,and overburd e n .
In addition, the effect and sensitivity of sett-
lement-especially in built-up are a s - s h o u l dbe given special attention. This is a decisivefactor in choosing the tunnelling and supportmethods, the tunnel alignment, and thec ro s s - s e c t i o n .
The environmental impact assessment shouldbe thorough, taking account of the density ofexisting works and the diversity of their beha-v i o u r s .
For existing underg round works, the com-patibility of the proposed tunnelling and sup-p o rt methods or the adaptations re q u i re d(special treatment or accompanying mea-s u res) should be assessed through speciala n a l y s i s .
8.1.2 - Ground conditions
The purpose of pre l i m i n a ry investigations isnot just for design of the temporary and per-manent works, but also to check the feasibi-lity of the project in constructional terms, i.e.with respect to excavation, mucking out, ands h o rt- and long-term stability.
Design of the works involves determ i n i n gshape, geological cross-sections, the physi-cal and mechanical characteristics of theg round encountered by the tunnel, and theh y d rogeological context of the project as aw h o l e .
P roject feasibility is determined by the poten-tial reactions of the ground, including detailsof both the formations traversed and of thet e rrain as a whole, with respect to the loa-dings generated by the works, i.e. with re s-pect to the excavation/confinement methoda d o p t e d .
Depending on the context and the specificre q u i rements of the project, the synopsis ofinvestigation results should there f o re dealwith each of the topics detailed in the AFTESrecommendations on the choice of geotech-nical tests and parameters, irrespective of thegeological context (cf.: T.O.S No. 28, 1978,re-issued 05/93 – review in pro g ress; andT.O.S No. 123, 1994).
If the excavation/confinement method isonly chosen at the tender stage, and depen-ding on the confinement method chosen bythe Contractor, additional investigationsmay have to be carried out to validate thevarious options adopted.
8.1.3 - Resources used
Depending on the magnitude and com-plexity of the project, pre l i m i n a ry investiga-tions - traditionally based on boreholes andb o rehole tests - may be extended to “larg e -scale” observation of the behaviour of theg round by means of test adits and shafts.
Advantage can be taken of the investigation
period to proceed with tests of the tunnellingand support methods as well as any asso-ciated tre a t m e n t s .
If there are to be forw a rd probe investiga-tions, matching of the boring and investiga-tion methods should be envisaged at the pre-l i m i n a ry investigation stage.
In the event of exceptional overburden condi-tions and difficult access from the surf a c e ,d i rectional drilling investigation (miningand/or petroleum industry techniques) oflong distances (one kilometre or more) alongthe tunnel alignment may be justified, espe-cially if it is associated with geophysicalinvestigations and appropriate in situ tes-t i n g .
8.2 - FORWARD PROBING
The concept of forw a rd probing must be setagainst the risk involved. This type of inves-tigation is cumbersome and costly, for itpenalizes tunnelling pro g ress since—in thecase of full-face and shield TBMs—themachine has to be stopped during pro b i n g(with current-day technology). It should the-re f o re be used only in response to an expli-cit and absolute re q u i rement to raise anyu n c e rtainty over the conditions to be expec-ted when crossing areas where site safety,p re s e rvation of existing works, or the dura-bility of the project might be at risk.
I rrespective of the methodology selected, itmust give the specialists implementing it re a lpossibilities for avoiding difficulties byimplementing corrective action in good time.
The first condition that forw a rd probing mustmeet in order to achieve this objective is thatit give sufficiently clear and objective infor-mation about the situation ahead of the face(between 1 and 5 times the tunnel diameterahead), with a leadtime consistent with therate of tunnel pro g ress.
The second condition is that in terms of qua-lity it must be adapted to the specific re q u i-rements of the project (identification of clearvoids, of decompressed areas, faults, etc.).These criteria should be determined jointlyby the Designer, Engineer, and Contractorand should be clearly featured in specifica-tions issued to the persons carrying out theinvestigations.
During tunnelling, analysis of results is gene-rally the responsibility of the investigationsc o n t r a c t o r, but the interpretation of data, inc o rrelation with TBM advance parameters(monitoring), should in principle be the re s-ponsibility of the contractor operating theT B M .
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8.3 - GROUND IMPROVE -M E N T
Prior ground improvement is sometimesn e c e s s a ry, particularly in order to cro s s :
• singular features such as break-ins andb reakouts, including on works along theroute (shafts, stations, etc.)
• discontinuities and fault zones identifiedb e f o rehand
• p e rmeable water-bearing gro u n d .
If the problem areas are of limited extent,g round improvement will sometimes enablea less sophisticated - and there f o re less costly- tunnelling technique to be adopted.
Since ground improvement is long and costlyto carry out from the tunnel (especially whenthe alignment is below the water table), thework is generally done from the surface (inthe case of shallow overburd e n ) .
These days, however, there is a trend forTBMs to be fitted with the basic equipment(such as penetrations in the bulkhead and/orcans) enabling ground improvement to bec a rried out from the machine should water-bearing ground not compatible with the tun-nelling technique adopted be encountere du n e x p e c t e d l y. This can also be the case whenlocal conditions prohibit treatment from thes u rf a c e .
When confinement-type TBMs are used,geological and hydrogeological conditionsoften re q u i re special treatment for bre a k - i n sand breakouts. This point should not be over-looked, neither at the pre l i m i n a ry designstage (surface occupation, ground and net-work investigations, works schedule) norduring the construction phase, for this is oneof the most difficult phases of tunnelling.
Special attention should be given to the com-patibility of ground treatment with the tun-nelling process (foaming, reaction withs l u rry and additives, etc.)
The most commonly used ground impro v e-ment techniques are :
• p e rm e a t i o n - g routed plug of bentonite-cement and/or gel
• diaphragm-wall box
• total replacement of soil by bentonite-c e m e n t
• j e t - g routed plug
8.4 - GUIDANCE
Guidance of full-face TBMs is vital. The per-f o rmance of the guidance system used mustbe consistent with the type of TBM and lining,and with the purpose of the tunnel.
The development of shield TBMs incorpora-ting simultaneous erection of precast seg-mental lining has led to the design of highlysophisticated guidance systems, becausewith tunnel lining it is impossible to re m e d ydevia t ion f rom the cor rec t cour se .C o n s e q u e n t l y, the operator (or automaticoperating system) must be given re a l - t i m ei n f o rmation on the position of the face andthe tunnelling trend relative to the theore t i c a lalignment. However, when considering thec o n s t ruction tolerance it must be re m e m b e-red that the lining will not necessarily be cen-t red in the excavation, and that it may be sub-je c t t o i ts own deformat ion (o f f s e t ,ovalization, etc.). The generally acceptedtolerance is an envelope forming a circ l eabout 20 cm larger in diameter than the theo-retical diameter.
Whatever the degree of sophistication of theguidance system, it is necessary to:
• reliably transfer a traverse into the tunneland close it as soon as possible (bre a k o u tinto shaft, station, etc.)
• c a rry out regular and precise topographi-cal checks of the position of the TBM and ofthe tunnel
• know how quickly (speed and distance) theTBM can react to modifications to the trajec-t o ry it is on.
8.5 - ADDITIVES
a) General Mechanized tunnelling techniques make useof products of widely differing physical andchemical natures that can all be labelled“conditioning fluids and slurries”. Before anychemical additives are used, it should bechecked that they present no danger for thee n v i ronment (they will be mixed in with themuck and could present problems when it isdisposed of) or for the workforce (part i c u-larly during pressurized work in the cutte-rhead chamber where the temperature canbe high).
b) Wa t e rWat er w i l l be pr esent in t he gr ound inv a rying quantities, and will determine thesoil's consistency, as can be seen from diff e-rent geotechnical characterization tests orc o n c rete tests (Atterberg limits for clayeysoils and slump or Abrams cone test for gra-nular soils). It can be used alone, with clay
(bentonite), with hydrosoluble polymers, orwith surfactants to form a conditioning fluid( s l u rry or foam).
c) AirBy itself air cannot be considered to be aboring additive in the same way as water orother products; its conditioning action is verylimited. When used in pressurized TBMs - ifthe permeability of the ground does not pro-hibit it - air helps support the tunnel. As ac o m p ressible fluid, air helps damp confine-m e n t - p re s s u re variations in the techniquesusing slurry machines with “air bubbles” andEPB machines with foam. As a constituent offoam, air also helps fluidify and reduce thedensity of muck, and helps regulate the confi-nement pre s s u re in the eart h - p re s s u re -balance pro c e s s .
d) BentoniteOf the many kinds of clay, bentonite is mostc e rtainly the best-known drilling or boringmud. It has extremely high swell, due to thep resence of its specific clayey constituent,montmorillonite, which gives it very intere s-ting colloidal and sealing qualities.
In the slurry-confinement technique, therheological qualities of bentonite (thixo-t ropy) make it possible to establish a confi-nement pre s s u re in a permeable medium bysealing the walls of the excavation thro u g hp ressurized filtration of the slurry into the soil( f o rmation of a sealing cake through a com-bination of permeation and membrane), andto transport muck by pumping.
Bentonite slurry can also be used with an EPBmachine, to improve the consistency of thegranular material excavated (homogeniza-tion, plastification, lubrication, etc.).
In permeable ground, the EPB technique usesthe same principle of cake formation beforework is carried out in the pressurized cutte-rhead chamber.
e) PolymersOf the multitude of products on the market,only hydrosoluble or dispersible compoundsa re of any interest as tunnelling additives.Most of these are well known products in thedrilling industry whose rheological pro p e r-ties have been enhanced to meet the specificre q u i rements of mechanized tunnelling.
These modifications essentially concernenhanced viscosifying power in order to bet-ter homogenize coarse granular materials,and enhanced lubrifying qualities in order tolimit sticking or clogging of the cutterh e a dand mucking out system when boring in cer-tain types of soil.
Polymers may be of three types:
• natural polymers (starch, guar gum, xan-
- Choosing mechanized tunnelling techniques
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Choosing mechanized tunnelling techniques
than gum, etc.)
• modified natural or semi-synthetic poly-mers (CMC [carboxymethylcellulose], etc.)
• synthetic polymers (polyacry l a m i d e s ,p o l y a c rylates, etc.)
f) Foams (surf a c t a n t s )Foams are two-phase systems (a gas phaseand a liquid phase containing the foamingagent) which are characterized physically bytheir expansion factor (volume occupied bythe air in the foam relative to the volume ofliquid).
Foams are easy to use. They are similar toaerated slurries, combining the advantagesof a gas (compre s s i b i l i t y, practically zerod e n s i t y, etc.) and of a slurry (fluidification,lubrication, pore filling, etc.). With EPBmachines they are used to facilitate confine-ment and sometimes excavation and muc-king out as well.
8.6 - DATA LOGGING
The acquisition and restitution of TBM ope-rating parameters is undoubtedly the biggestfactor in the technical pro g ress of mechani-zed tunnelling in the last ten years.
It makes for objective analysis of the opera-ting status and dysfunctions of the machineand its auxiliaries.
The status of the machine at any given timeis short-lived and changes rapidly. Wi t h o u tdata logging, this gave rise to varied andoften erroneous interpretations in the past.
Logging gives a “true” technical analysis thatis indispensable for smooth operation onp rojects in difficult or sensitive sites.
Data logging also provides a basis for com-puterized control of TBM operation andautomation of its functions (guidance, muc-king out, confinement pre s s u re re g u l a t i o n ,e t c . ) .
Data logging also provides an exact re c o rdof operating statuses and their durations (cf.recommendation on analysis of TBM opera-ting time and coefficients, TOS No. 148, July9 8 ) .
They also constitute operating feedback thatcan be used to optimize TBM use.
8.7 - TUNNEL LINING ANDB A C K G R O U T I N G
8.7.1 - General
In t he case of segment al TBMs, t helining and its backgrouting are inseparablef rom the operation of the machine.
Without any transition and in perf e c t l yc o n t rolled fashion, the lining and backgro u tmust balance the hydrostatic pre s s u re, sup-p o rt the excavation peripherally, and limits u rface settlement.
Because of their interfaces with the machine,they must be designed in parallel and ini n t e rdependence with the TBM.
8.7.2 - Lining
The lining behind a shield TBM generallyconsists of re i n f o rced concrete segments.Sometimes (for small-diameter tunnels) cast-i ron segments are used. More exceptionallythe lining is slipcast behind a sliding form .
R e i n f o rced concrete segments are by far themost commonly used. The other techniquesa re gradually being phased out for econo-mic or technical re a s o n s .
The segments are erected by a machineincorporated into the TBM which grips themeither mechanically or by means of suction.
The following AFTES recommendations exa-mine tunnel lining:
• Recommandations sur les re v ê t e m e n t spréfabriqués des tunnels circ u l a i res au tun-nelier (Recommendations on precast liningof bored circular tunnels), TOS No. 86
• Recommandation sur les joints d’étan-chéité entre voussoirs (Recommendations ongaskets between lining segments), TOS No.116, March/April 1993
• Recommandations “pour la conception etle dimensionnement des revêtements envoussoirs préfabriqués en béton armé instal-lé s à l ’ar r i è re d ’un tunne l i er”(Recommendations “on the design of pre c a s tre i n f o rced concrete lining segments installedbehind TBMs”) drawn up by AFTES workg roup No. 18, published in TOS No. 147,May/June 1998.
8.7.3 - Backgrouting
This section concerns only mechanized tun-nelling techniques involving segmentall i n i n g .
Experience shows the extreme importance ofc o n t rolling the grouting pre s s u re and fillingof the annular space in order to control andrestrict settlement at the surface and to secu-rely block the lining ring in position, giventhat in the short term the lining is subject toits selfweight, TBM thrust, and possibly flota-tional forc e s .
G routing should be carried out continuously,with constant control , as the machineadvances, before a gap appears behind theTBM tailskin.
In the early days backfilling consisted of
either pea gravel or fast-setting or fast-har-dening cement slurry or mortar that wasinjected intermittently through holes in thes e g m e n t s .
Since management of the grout and its har-dening between mixing and injection is av e ry complex task, there has been a constantt rend to drop cement-based products infavour of products with re t a rded set (pozzo-lanic reac t ion) and low compre s s i v es t rength. Such products are injected conti-nuously and directly into the annular spaced i rectly behind the TBM tailskin by means ofg rout pipes routed through the tailskin.
9 - HEALTH AND SAFETYMechanization of tunnelling has very sub-stantially improved the health and safetyconditions of tunnellers. However, it has alsoinduced or magnified certain specific risksthat should not be overlooked. These include:• risk of electrical fire or spread of fire tohydraulic oils• risk of electro c u t i o n• risks during or subsequent to compre s s e d -air work • risks inherent to handling of heavy part s(lining segments)• mechanical risks• risk of falls and slips (walkways, ladders,e t c . )
9.1 - DESIGN OF TUNNEL -LING MACHINES
Tunnelling machines are work items that mustcomply with the regulations of the MachineryD i rective of the European Committee forS t a n d a rdization (CEN).
These regulations are aimed primarily atdesigners—with a view to obtaining equip-ment compliant with the Directive—but alsoat users.
The standards give the minimum safety mea-s u res and re q u i rements for the specific risksassociated with the diff e rent kinds of tunnel-ling machines. Primarily they apply tomachines manufactured after the date ofa p p roval of the European standard .• At the time of writing only one standardhad been homologated:- NF EN 815 “Safety of unshielded tunnelboring machines and rodless shaft boringmachines for rock” (December 1996)• T h ree are in the approval pro c e s s :- Pr EN 12111 “Tunnelling machines -Roadheaders, continuous miners and impact
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rippers – Safety re q u i re m e n t s ”- Pr EN 12336 “Tunnelling machines –Shield machines, horizontal thrust boringmachines, lining erection equipment - Safetyre q u i rements ”- Pr EN 12110 “Tunnelling machines –Airlocks – Safety re q u i rements ”
9.2 - USE OF TUNNELLINGM A C H I N E S
Machine excavation of underg round worksinvolves specific risks linked essentially toatmospheric pollution (gas, toxic gases,noise, temperature), flammable gases andother flammable products in the gro u n d ,electrical equipment (low and high voltage),hydraulic equipment (power or contro ldevices), and compressed-air work (work inl a rge-diameter cutterhead chambers underc o m p ressed air, pressurization of whole sec-tions of small-diameter tunnels).
A variety of bodies dealing with safety onpublic works projects have drawn up textsand recommendations on safety. In France,these include OPPBTP, CRAM, and INRS, fore x a m p l e .
All their re q u i rements should be incorpora-ted into the General Co-Ordination Plan andHealth and Safety Plan at the start of works.
APPENDICES 1, 2, 3, AND 41 . Comments on Table No. 1 in Chapter 52 . Comments on Table No. 2 in Chapter 53 . G round classification table4 . Mechanized tunnelling project datas h e e t s
Choosing mechanized tunnelling techniques
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Choosing mechanized tunnelling techniques
APPENDIX 1
COMMENTS ON TABLE NO.1 IN CHAPTER 5.
1 - Natural constraints
S u p p o rt (columns A and B)With knowledge of natural constraints:• a choice can be made f r om among t het unnel l i ng t echni que gr oups ( f r omboom- t y pe uni t s t o conf inement - t y peTBMs)
• r elax at ion of st r esses can be mana-ged ( f r om s i m pl e def or m at i on-conv er gence t o f ai lur e) .
2 - PHYSICAL PARAMETERS
2.1 - Identification
❑ Face suppor t (column A )
Wi t h know ledge of phy sical par ame-t er s:
• t he suppor t met hod can be assessed,and t he t unnel l i ng t echnique gr oupchosen
• t he r equi r ement f or f ace suppor tcan be assessed.
❑ Per ipher al suppor t (column B)
Wi t h know ledge of phy sical par ame-t er s t he r equi r ement f or per ipher alsuppor t ar ound t he machine can beassessed.
❑ Opposi t ion t o hy dr ost at ic pr essur e(column C)
Wi t h know ledge of phy sical par ame-t er s and of gr ain and block sizes, t heper meabi l i t y of t he t er r ai n can beassessed, leading t o a pr oposal f or t hew ay hy dr ost at i c pr essur e could becont r ol led.
❑ Ex cav at ion (column D)
Of t he par amet er s concer ned, gr ainand block size ar e decisiv e f or asses-sing t he ex cav at ion met hod (design ofcut t er head, cut t er s, et c.) .
2 . 2 - Global appre c i a t i o nof quality
❑ Suppor t (columns A and B)
Global appr eci at i on of qual i t y pr o-v ides addi t ional inf or mat ion f or iden-t i f i cat i on t hat concer ns onl y t hesample. This dat a def ines mor e globalinf or mat ion at t he scale of t he soi lhor izon concer ned.
2.3 - Discontinuities
❑ Suppor t (columns A and B)
This dat a concer ns r ock and coher entsof t gr ound. Wi t h know ledge of dis-cont i nui t i es a choi ce can be madeamong t he t unnel t echnique gr oups( f r om boom- t y pe uni t s t o conf ine-ment - t y pe TBMs).
❑ Opposi t ion t o hy dr ost at ic pr essur e(column C)
Wi t h know ledge of discont inui t ies t hecr ack per meabi l i t y and w at er pr es-sur e t o be t aken int o account f or t hepr oj ect can be assessed. This enablest he t y pe of t echnique t o be chosen.
❑ Ex cav at ion (column D)
In conj unct ion w i t h know ledge of blocksi zes, know ledge of di scont i nui t ies(nat ur e, size, and f r equency ) can bedecisiv e or mer ely hav e an ef f ect ont he ex cav at ion met hod t o be adopt ed.
3 - MECHANICAL PARAME-TERS
3.1 - Stre n g t h
❑ Suppor t (columns A and B)
Wi t h know ledge of mechani cal par a-met er s a pr el iminar y choice can bemade f r om among t he t unnel l ing t ech-nique gr oups ( f r om boom- t y pe uni t st o conf inement - t y pe TBMs).
❑ Ex cav at ion (har d r ock)(column D)
Know ledge of mechani cal par amet er sis par t icular ly impor t ant f or def ining
t he ar chi t ect ur e of t he machine andhelps det er mine i t s t echnical char ac-t er ist i cs ( t or que, pow er , et c.) andt he choice of cut t ing t ools.
3 . 2 - Deform a b i l i t y
❑ Suppor t (columns A and B)
Wi t h know ledge of def or mabi l i t y t her elax at ion of st r esses can be asses-sed and t aken i nt o account ( f r omsimple def or mat ion or conv er gence t of ai lur e) .
3 . 3 - Liquefaction potential
❑ Suppor t and mucking out (columnsA, B and E)
Know ledge of t he l iquef act ion pot en-t ial has an ef f ect in sei smic zones andin cases w her e t he t echnique chosenmight set up v ibr at i ons in t he gr ound(blast i ng, et c.) .
4 - HYDROGEOLOGICALPARAMETERS❑ Suppor t , opposi t ion t o hy dr ost at icpr essur e, and ex cav at i on (ColumnsA, B, C and D)
Know ledge of t hese par amet er s i sdecisiv e in appr eciat i ng cont r ol of t hest abi l i t y of t he t unnel , bot h at t he f aceand per i pher al l y , and t her ef or e i nchoosing t he met hod f r om t he v ar ioust unnel l ing t echniques. In t he case oft unnels beneat h deep ov er bur den i t isnot easy t o obt ain t hese par amet er s.They should be est imat ed w i t h t hegr eat est car e and analy zed w i t h cau-t ion.
5 - OTHER PARAMETERS❑ Ex c av a t i on and m uc k i ng ou t(Columns D and E)
The par amet er s of abr asiv eness andhar dness ar e deci si v e or hav e anef f ect in appr eciat ion of t he ex cav a-t ion and mucking- out met hods t o beused. These par amet er s should be
Comments on Table No. 1 inChapter 5
1 - NATURAL CONSTRAINTSThe st r ess pat t er n in t he gr ound is ver yimpor t ant in deep t unnels or in cases ofhigh anisot r opy . If t he r ate of st r essr elease is high, w it h main- beam TBMs,shield TBMs, and r eaming machines, itmay cause:
• j amming of the machine (j amming oft he cut ter head or body)
• r ockbur st at t he f ace or in t unnel walls,r oof , or inver t .
Wit h slur r y - shield TBMs or EPBMs it isr ar e for t he natur al st r ess pat ter n t o bedecisive in t he choice of machine t ypesince t hey ar e gener ally used f or shal-low t unnels.
2 - PHYSICAL PA R A M E T E R S
2.1 - Identification
The t ype of gr ound plays a decisive r olein t he choice and design of a shield TBM.Consequent ly the par ameter s char acte-r izing t he ident if icat ion of t he gr oundmust be examined car efully when choo-sing t he excavat ion/ suppor t method.
The most impor t ant of t he ident if icat ionpar ameter s ar e plast icity and - f orhar dness, clogging potent ial, and abr a-siveness - miner alogy which ar e par -t icular ly decisive in t he select ion ofshield TBM component s.
Chemical analysis of t he soil can be deci-siv e in t he case of conf inement - t ypeshield TBMs because of t he ef f ect soilmight have on t he addit ives used in t hesetechniques.
2.2 - Global appreciation ofq u a l i t y
Global appr eciat ion of quali t y r esult sf r om combining par ameter s which ar eeasy t o measur e in t he labor ator y or insi t u (bor ehole logs, RQD) and v isualappr oaches.
Weat her ed zones and zones w i t hcont r ast ing har dness can cause specif icdif f icult ies f or t he dif f er ent t unnell ingtechniques, e.g. f ace instabil i ty , insuf f i-
cient st r ength f or gr ipper s, conf inementdif f icult ies.
The degr ee of weather ing of r ock has anef f ect but is not gener ally decisive forslur r y shields and EPBMs. In all cases ithas an ef f ect f or cut t er head design.
2.3 - Discontinuities
For r ock, know ledge of t he si t uat ionr egar ding discont inui t ies is decisiv e(or ientat ion and densit y of t he networ k),f or it w ill af f ect t he choice of t he tun-nell ing and suppor t t echnique as well asthe tunnell ing speed.
Wi th open- f ace main- beam TBMs andshields and mechanical- suppor t TBMs,at t ent ion should be given to t he r isk ofj amming of t he machine induced by thedensit y of a networ k of discont inuit ieswhich could quit e r apidly lead to doubt -f ul st abil i t y of the t er r ain. The ex ist enceof unconsolidated inf i l l ing mater ial canaggr avate t he r esult ing instabili t y .
The pr esence of maj or discont inuit iescan have a maj or ef fect on t he choice oft unnell ing technique.
Slur r y shi el ds and compr essed- ai rTBMs ar e gener ally mor e sensit ive t ot he pr esence of discont inui t ies t hanEPBMs. If t her e ar e maj or discont inui-t ies (high densit y of f r actur at ion), thecompr essed- air conf inement TBM mayhave t o be eliminated f r om the possibler ange.
In gener al t he over all per meabil i ty of theter r ain should be examined in conj unc-t i on w i t h i t s di scont inui t i es bef or eselect ing t he type of conf inement .
2 . 4 - Alterability
Al t er abi l i t y char act er ist ics concer nt er r ai n t hat i s sensi t iv e t o w at er .Alt er abili t y data should be obtained att he ident if icat ion st age.
Special at t ent ion should be given t o alte-r abil i t y when mechanized t unnell ing is t ot ake place in water - sensit iv e gr oundsuch as cer tain molasses, mar ls, cer t ainschist s, act ive clays, indur ated clays,etc.
Alt er abil i t y has an ef f ect on conf ine-ment - t ype TBMs; it can r esult in changesbeing made to t he design of t he machineand t he choice of addit ives.
2.5 - Water chemistry
Pr oblems r elated t o t he aggr essiv it y ort he degr ee of pollut ion of water mayar ise in ver y specif ic cases and have t obe dealt w it h r egar dless of t he t unnell ingpr inciples adopted.
Wit h conf inement - t ype TBMs t his par a-meter may be decisive because of i t sef f ect on t he qualit y of t he slur r y oraddit ives.
3 - MECHANICAL PA R A M E-T E R S
3 . 1 - Stre n g t h
In t he case of r ock, t he essent ial mecha-nical cr it er ia ar e the compr essive andtensile st r ength of the t er r ain, f or t heycondit ion t he ef f icacy of excavat ion.
In sof t gr ound, t he essent ial cr it er ia ar ecohesion and t he angle of f r ict ion, f ort hey condit ion t he hold- up of t he f ace andof t he excavat ion as a whole.
The ver y high st r engths of some r ocksexclude t he use of boom- t ype t unnell ingmachines (unless t hey ar e highly cr ac-ked). Gr ipper - t y pe t unnel bor ing andr eaming machines ar e ver y sensit ive t olow - st r ength gr ound and may r equir especial adaptat ion of t he gr ipper pads.For main- beam and shield TBMs alike,t he machine ar chit ectur e, t he installedpower at t he cut t er head, and t he choiceand design of cut t ing t ools and cut t er headar e condit ioned by t he st r ength of t hegr ound.
If t her e is any chance of t unnel bear ingcapaci t y being insuf f i cient , specialt r eat ment may be necessar y f or t hemachine to advance.
3.2 - Deform a b i l i t y
Defor mabil i ty of t he t er r ain may causej amming of the TBM, especially in t heev ent of conver gence r esul t ing f r omhi gh s t r esses ( see par agr aph 1 ,“ Natur al const r aint s” ).
In the case of t unnel r eamer s and open-f ace or mechanical- suppor t TBMs, t hiscr it er ion af f ects the appr eciat ion of t her isks of cut ter head or shield j amming.
In the case of excessively defor mablemater ial, t he design of TBM gr ipper padsw il l have t o be st udied car efully . The
Choosing mechanized tunnelling techniques
IV-21
APPENDIX 2
Choosing mechanized tunnelling techniques
defor mabil it y of the sur r ounding gr oundalso af f ect s TBM guidance. If t he t unnell ining is er ected t o t he r ear of the t ails-kin, at t ent ion should be paid to t he r iskof defer r ed defor mat ion.
In gr ound t hat swel ls in contact w it hw at er , t he r esul t ing di f f icul t ies f oradvancing t he machine ar e compar ablefor both slur r y shield and EPB machines,in so f ar as t he swell ing is due t o t he dif -f usion and absor pt ion of water w it hin t hedecompr essed gr ound ar ound t he t unnel.Compr essed- air TBMs ar e less sensi-t ive t o t his phenomenon.
3.3 - Liquefaction potential
Not applicable, except if t her e is a r iskof ear t hquake or if t he gr ound is par t i-cular ly sensit ive (satur ated sand, et c.).
4 - HYDROGEOLOGICALPA R A M E T E R SThe pur pose of examining t he hydr ogeo-logical par ameter s of t he t er r ain is t oensur e t hat it w il l r emain st able in t heshor t ter m. The pr esence of high waterpr essur es and/ or potent ial inf low r atesent r aining mater ial w il l pr ohibit t he useof boom- t ype machines and open- f ace ormechanical - suppor t machines unlessaccompany ing measur es such as gr oundimpr ov ement , gr oundw ater lower ing,et c. ar e car r ied out .
Water pr essur e is also decisive whengeological accident s (e.g. my lonit e) haveto be cr ossed, ir r espect ive of whetheror not t hey ar e inf i l led w ith loose soil.
Gr ound per meabil i t y and hydr ostat icpr essur e ar e decisive f or TBMs usingcompr essed- air , slur r y , or EPB conf i-nement . Compr essed- air machines mayeven be r ej ected because of t hese f ac-t or s, and t hey ar e par t icular ly decisivefor EPBMs when t her e ar e likely t o besudden var iat ions in per meabili t y . Forslur r y shield TBMs, t he ef f ects of t hesepar ameter s ar e at t enuated by t he f actt hat a f luid is used for mucking out .
5 - OTHER PA R A M E T E R S
5.1 - Abrasiveness - Hard n e s s
Ex cessi v el y hi gh abr asi v eness andhar dness make it impossible or unecono-m i c t o use boom- t y pe t unnel l i ngmachines.
Abr asiveness and har dness can be deci-siv e w i t h r espect t o t ool w ear , t hest r uctur e of t he cut t er head, and ex t r a-ct ion systems (scr ew conveyor , slur r ypipes, et c.) . How ev er , t he ex pect edwear can be counter ed by using bor ingand/ or ex t r act ion addit ives and/ or pr o-t ect ion or r einf or cement on sensit ivepar t s.
5.2 - Sticking - Clogging
When t he potent ial t he mat er ial t o beexcavated has t o st ick or clog is known,the cut t er s of boom- t ype unit s, t unnelr eamer s, or shield TBMs can be adaptedor use of an addit ive env isaged.
This par ameter alone cannot exclude atype of shield TBM; it is t her efor e notdecisive f or f ace- conf inement shields.However , t he t r end f or t he gr ound t ost ick must be examined w it h r espect t ot he development of addi t ives ( f oam,admix tur es, et c.) and t he design of t heequipment f or chur ning and mix ing t hest icky spoil (agit at or s, j et t ing, et c.).
The t r anspor t of muck by t r ains and/ orconveyor s is par t icular ly sensit ive t othis par ameter .
5.3 - Ground/machine friction
For shield TBMs t he pr oblem of gr oundfr ict ion on t he shield can be cr it ical ingr ound wher e conver gence is high.
Wher e t her e is a r eal r isk of TBM j am-ming (conver gence, swell ing, dil i t ancy ,et c.) t his par ameter has a par t icular lyimpor t ant ef f ect on t he design of t heshield.
The lubr icat ion pr ov ided by t heir bento-nit e slur r y makes slur r y shield TBMsless suscept i bl e t o t he pr oblems ofgr ound/ machine f r ict ion.
5.4 - Presence of gas
The pr esence of gas in t he gr ound candeter mine t he equipment f i t t ed t o t hemachine.
6 - PROJECT CHARACTERIS-T I C S
6.1 - Dimensions and sections
Boom- t ype units can excavate tunnels ofany shape and sect ional ar ea. ShieldTBMs, main- beam machines, and r ea-
mer s can excavate t unnels of constantshape only . The sect ional ar ea t hat canbe excavated is r elat ed to t he st abil i t yof t he f ace.
The sect ional ar ea of t unnels is decisivef or l ar ge- di amet er EPBMs (pow err equir ed at t he cut t er head).
The length of t he pr oj ect can have anef f ect on slur r y shield TBMs (pumpingdist ance).
6.2 - Ve rtical alignment
The l i m i t s i mposed on t unnel l i ngmachines by t he v er t ical pr of i le ar egener ally those of t he associated logis-t ics. Main- beam tunnel bor ing and r ea-ming machines can be adapted t o bor einclined t unnels, but t he r equir ement f orspecial equipment t akes t hem beyond t hescope of t hese r ecommendat ions.
Wit h boom- t ype units and open- f ace ormechani cal - suppor t TBMs, w at erinf low can cause pr oblems in downgr adedr ives.
6 . 3 - Horizontal alignment
❑ The use of boom- type unit s imposes nopar t icular const r aint s.
❑ The use of main- beam tunnel bor ingand r eaming machines and of shield TBMsis l imit ed to cer t ain r adii of cur vatur e( ev en w i t h ar t i c ul at i ons on t hemachines).
❑ Wi t h shi el d TBMs t he al i gnmentaf t er / befor e br eak- ins and br eakout sshould be st r aight f or at least tw ice t helength of the shield (since it is impossiblet o st eer t he machine when it is on its sl idecr adle).
6 . 4 - Enviro n m e n t
6.4.1 - Sensitivity to settlement
Since boom- t ype unit s, t unnel r eamer s,main- beam TBMs, and open- face shieldTBMs do not gener al l y pr ov i de anyimmediate suppor t , t hey can engenderset t lement at t he sur f ace. Set t lementw il l be par t icular ly decisive in ur ban orsensit ive zones (t r ansit s below r outesof communicat ion such as r ai lw ay s,pipelines, et c.).
Sensit iv it y t o set t lement is gener allydecisive f or all TBM t ypes and can leadto exclusion of a given t echnique.
Open- f ace or mechanical- suppor t shieldTBMs ar e not suit able f or use in ver y
IV-22
defor mable gr ound. If t he t unnel l ining iser ected t o t he r ear of t he t ailskin, at t en-t ion should be paid t o the r isk of defer -r ed def or mat ion of t he sur r oundinggr ound.
With conf inement - t ype TBMs, cont r ol ofset t lement is closely l inked to t hat ofconf inement pr essur e.
Wit h compr essed- air shields t he r isk ofset t lement lies in loss of air (sudden orgr adual).
Wit h slur r y shield TBMs t he r isk l ies int he qualit y of t he cake and in t he r egula-t ion of t he pr essur e. In r elat ion t o t his,t he “ air bubble” conf inement pr essur er egulat ion sy st em per f or ms par t icu-lar ly well.
Wit h EPBMs t he r isk lies in less pr eciser egulat ion of t he conf inement pr essur e.Mor eover , the annular space ar ound t heshield is not pr oper ly conf ined, unlessar r angements ar e made t o inj ect slur r yt hr ough the cans.
6.4.2 - Sensitivity to disturbance andwork constraints
Slur r y shield machines r equir e a lar gear ea at t he sur f ace f or the slur r y sepa-
r at ion plant . This const r aint can have anef f ect on t he choice of TBM t ype or evenbe decisive in int ensively built - up zones.
The addit ives int r oduced int o t he cut te-r head chamber of shield TBMs (bento-ni t e, poly mer , sur f act ant , et c.) mayimply const r aint s on disposal of spoil.
6 . 5 - Anomalies in gro u n d
6.5.1 - Ground/accident hetero g e n e i-t y
Mixed har d r ock/ sof t gr ound gener allyimplies f ace- stabil it y and gr ipping pr o-blems f or t unnell ing t echniques w ith noconf inement , and also int r oduces a r iskof cav ing- in of t he r oof wher e the gr oundis sof t est .
6.5.2 - Natural and artificial obs-t a c l e s
For “ open” techniques it is essent ial t obe able t o detect geological accident s. Forconf inement t echniques at t ent ion shouldbe paid t o t he pr esence of obst acles,whether natur al or ar t if icial. Obstaclescan hav e an ef f ect on t he choice ofmachine, depending on t he dif f icult ies
encounter ed in over coming t he obstacleand t he need to wor k f r om the cut t er headchamber .
Compr essed- ai r w or k necessar y f ordet ect ing and deal ing w i t h obst aclesr equir es r eplacement of t he pr oducts int he cut t er head chamber ( pr oduct sdepending on t he conf inement method)w it h compr essed air .
The wor k r equir ed f or r eplacing them is:
❑ f aster and simpler wit h a compr es-sed- air TBM (in pr inciple)
❑ easy w it h a slur r y shield TBM
❑ longer and mor e dif f icult w it h an ear t hpr essur e balance machine (ex t r act ion oft he ear t h and subst itut ion w it h slur r y t of or m a sealing f i lm, f ol lowed by r emo-val of the bulk of t he slur r y and r eplace-ment w it h compr essed air ).
6.5.3 - Vo i d s
Depending on t heir size, t he pr esence ofv oids can engender v er y substant ialdev iat ion f r om the design t r aj ector y ,especially ver t ically . They can also be asour ce of dist ur bance t o t he conf inementpr essur e, par t icular ly w it h compr es-sed- air or slur r y shield TBMs.
Choosing mechanized tunnelling techniques
IV-23
APPENDIX 3
Ground classification table (cf. GT7)
Cat égor y Descr ipt ion Ex amples RC (Mpa)
R1 Ver y st r ong r ock St r ong quar t zi t e and basal t > 200
R2a Ver y st r ong gr ani t e, por phy r y , v er y st r ongSt r ong r ock sandst one and l imest one 200 à 120
R2b Gr ani t e, v er y r esist ant or sl ight ly dolomi t i zed sandst one and 120 à 60l imest one, mar ble, dolomi t e, compact conglomer at e
Or dinar y sandst one, si l i ceous schist or R3aModer at ely st r ong r ock schist ose sandst one, gneiss
60 à 40
R3b Clay ey schist , moder at ely st r ong sandst one and l imest one, 40 à 20compact mar l , poor ly cement ed conglomer at e
Schist or sof t or highly cr acked l imest one, gy psum, 20 à 6R4 Low st r engt h r ock highly cr acked or mar ly sandst one, puddingst one, chalk
R5 a Ver y low st r engt h r ock and Sandy or clay ey mar ls, mar ly sand, gy psumconsol idat ed cohesiv e soi l s or w eat her ed chalk
6 à 0, 5
R5b Gr av el ly al luv ium, nor mal ly consol idat ed clay ey sand < 0, 5
R6aPlast ic or sl ight ly consol idat ed soi l s Weat her ed mar l , plain clay , clay ey sand, f ine loam
R6b Peat , si l t and l i t t le consol idat ed mud, f ine non- cohesiv e sand
IV-24
Choosing mechanized tunnelling techniques
APPENDIX 3
Mechanized tunnelling data sheets (up to 31/12/99).
1 Echaillon D 68 1972-1973 43 62 5 .8 0 Gneiss, f lysch, limest one Wirt h2 La Coche D 77 1972 -1973 5287 3.0 0 Limestone, sandst one, breccia Robbins3 CERN SPS H 64 1973 -1974 65 51 4 .8 0 Molasse Robbins4 RER Chât elet -Gare de Lyon C 64 1973 -1975 51 00 7 .00 Limest one Robbins5 Belledonne D 64 1974-1978 9998 5.8 8 Schist , sediment ary granit e Wirt h6 Bramefarine D 67 1975 -1977 37 00 8 .1 0 Limest one, schist Robbins7 Lyons met ro - Crémaillère C 64 1976 220 3.0 8 Gneiss, granit e Wirt h8 Galerie du Bourget C 67 1976 -1978 48 45 6 m2 Limest one, molasse Alpine9 Monaco - Service t unnel H 64 1977 913 3 .30 Limest one, marne Robbins
10 Grand Maison - Eau Dolle D 64 1978 839 3.6 0 Gneiss, schist , dolomit e Wirt h1 1 West ern Oslof jord G 77 1978 -1984 10500 3.0 0 Slat e, limest one, igneous rock Bouygues 12 Brevon D 66 1979 -1981 41 50 3 .0 0 Limest one, dolomite, other Bouygues
calcareous rock (malm)1 3 Grand Maison D 75 1979-1982 54 66 3 .60 Gneiss, schist Wirt h
( penstocks and service shaf t )1 4 Marignan aqueduct F 66 1979 -1980 480 5.52 m2 Limest one Alpine1 5 Super Bissort e D 73 1980 -1981 29 75 3 .60 Schist , sandst one Wirt h1 6 Pouget D 66 1980 -1981 39 99 5 .0 5 Gneiss Wirt h1 7 Grand Maison - Vaujany D 75 1981-1983 5400 7.7 0 Lipt init e, gneiss, amphibolit e Robbins18 Vieux Pré D 68 1981-1982 1257 2.90 Sandst one, conglomeratee Bouygues19 Haut e Romanche Tunnel D 73 1981 -1982 28 60 3 .60 Limest one, schist , crystalline sandst one Wirt h2 0 Cilaos F 80 1982 -1984 57 01 3 .0 0 Basalt , t uf f Wirt h21 Monaco - t unnel No. 6 A 66 1982 183 5.0 5 Limest one, dolomit e Wirt h2 2 Ferrières D 79 1982 -1985 43 13 5 .90 Schist , gneiss Wirt h23 Durolle D 79 1983 -1984 21 39 3 .4 0 Granit e, quart z, microgranit e Wirt h24 Mont fermy D 80 1983 -1985 50 40 3 .5 5 Gneiss, anat exite, granit e Robbins2 5 CERN LEP (machines 1 and 2) H 82 1985 -1986 14680 4 .5 0 Molasse Wirt h 2 6 CERN LEP (machine 3) H 82 1985-1987 4706 4.5 0 Molasse Wirt h2 7 Val d' Isère funicular B 97 1986 16 89 4 .20 Limest one, dolomit e, cargneule Wirt h
(cellular dolomit e)2 8 Calavon and Luberon F 97 1987 -1988 27 87 3 .4 0 Limest one Wirt h29 Takamaka II D 101 1985 -1987 48 03 3 .20 Basalt , t uf f , agglomerat es Bouygues3 0 Oued Lakhdar D 101 1986-1987 6394 4.56 / 4.80 Limest one, sandst one, marl Wirt h3 1 Paluel nuclear power plant E 105 1980 -1982 24 27 5 .0 0 Chalk Zokor3 2 Penly nuclear power plant E 105 1986 -1988 25 10 5 .1 5 Clay Zokor 3 3 Lyons river crossing - met ro line D C 106 1984-1987 2 x 1230 6.5 0 Recent alluvium and granit ic sand Bade3 4 Lille met ro, line 1b - Package 8 C 106 1986-1987 1000 7.6 5 Whit e chalk and f lint FCB/ Kawasaki3 5 Lille met ro, Line 1b - Package 3 C 106 1986-1988 3259 7.7 0 Clayey sand and silt Herrenknecht3 6 Villejust t unnel B 106 1986 -1988 48 05 9 .25 Font ainebleau sand Bade/ Theelen
+ 4798 (2 machines)3 7 Bordeaux: Cauderan-Naujac G 106 1986-1988 1936 5.0 2 Sand, marl and limest one Bessac3 8 Caracas met ro: package PS 01 C 107 1986 -1987 2 x 1564 5 .7 0 Silt y-sandy alluvium, gravel, and clay Lovat 39 Caracas met ro: package CP 03 C 107 1987 2 x 2131 5.70 Weat hered micaschist and silt y sand Lovat 4 0 Caracas met ro: package CP 04 C 107 1987 -1988 2 x 714 5.7 0 Micaschist Lovat 4 1 Singapore met ro: package 106 C 107 1985 -1986 26 00 5 .8 9 Sandst one, marl and clay Grosvenor42 Bordeaux: " boulevards" G 113 1989 -1990 14 61 4 .36 Karst ic limest one and alluvium Bessac
main sewers Ø38004 3 Bordeaux: Avenue de la Libérat ion G 113 1988 -1989 918 2.9 5 Karst ic limest one and alluvium Bessac
Ø22004 4 St Maur-Crét eil, sect ion 2 G 113 1988 -1990 15 30 3 .3 5 Old alluvium and boulders FCB4 5 Crosne-Villeneuve St Georges G 113 1988 -1990 911 2.5 8 Weat hered marl and indurat ed limest one Howden46 Channel Tunnel T1 B 114 1988 -1990 15618 5 .7 7 Blue chalk Robbins4 7 Channel Tunnel T2-T3 B 114 1988 -1991 20009 8 .7 8 Blue chalk Robbins/
+18 860 Kawasaki
*AITES classif icat ion of project t ypesA road t unnels - B rail t unnels - C met ros - D hydropower t unnels - E nuclear and fossil-fuel power plant t unnels - F wat er t unnels - G sewers-H service t unnels - I access inclines - J underground st orage facilit ies - K mines -
Dat eBoredlengt h (m)
Boreddiameter
(m)
GeologyProject
IV-25
Choosing mechanized tunnelling techniques
48 Channel Tunnel T4 B 114 1988-19 89 3162 5.61 Grey and whit e chalk Mit subishi49 Channel Tunnel T5-T6 B 1 14 19 88 -1 990 2 x 326 5 8.64 Grey and whit e chalk Mit subishi50 Sèvres - Achères: Package 3 G 1 21 1989 -1 991 3550 4.05 Coarse limest one, sand, upper Landenian
clay ( fausses glaises) , plast ic clay, HerrenknechtMont ian marl, chalk
51 Sèvres - Achères: Packages 4 and 5 G 1 21 19 88 -1 990 3312 4.8 Sand, upper Landenian clay ( fausses glaises) , plast ic clay, Mont ian marl and limest one, chalk Lovat
53 Orly Val: Package 2 C 1 24 1989 - 1990 1160 7.64 Marl wit h beds of gypsum Howden54 Bordeaux Caudéran -
Naujac Rue de la Libert é G 1 26 1 991 150 3.84 Karst ic limest one Bessac55 Bordeaux Amont Taudin G 1 26 1 991 5 00 2.88 Alluvium and karst ic limest one Howden56 Rouen "Mét robus" C 1 26 1 993 8 00 8.33 Black clay, middle Albian sand and Gault clay Herrenknecht57 Toulouse met ro: Package 3 C 1 31 19 89 -1 991 3150 7.65 Clayey-sandy molasse and beds FCB /
of sandst one Kawasaki58 Toulouse met ro: Packages 4 and 5 C 131 19 90 -1991 1587 5.6 Molasse Lovat
+1 48759 Lille met ro: Line 2 Package 1 C 1 32 1992 - 1994 5043 7.65 Flanders clay FCB60 Lille met ro: Line 2 Sect ion b C 132 1992 - 1993 1473 7.65 Chalk, clay, and sandy chalk FCB61 St Maur: VL3 c main sewer G 133 1992 - 1994 1350 3.5 Very het erogenous plast ic clay, sand,
coarse limest one,andupper Landenian clay Herrenknecht62 Lyons met ro: Line D
Vaise - Gorge de Loup C 1 33 1993 - 1995 2 x 875 6.27 Sand, gravel, and clayey silt Herrenknecht63 METEOR Line 14 C 1 42 1993 - 1995 4500 8.61 Sand, limest one, marl,upper Lut et ian
marl/ limest one ( caillasses) HDW64 RER Line D Chat elet / Gare de Lyon C 142 1993 - 19942 x 160 0 7.08 Coarse limest one Lovat65 Cleuson Dixence Package D D 142 1994 - 1996 2300 4.77 Limest one, quart zit es, schist , sandst one Robbins
Inclined shaft66 Cleuson Dixence Inclined shaf t D 1 42 1994 - 1996 4 00 4.4 Limest one, schist , sandst one Lovat67 Cleuson Dixence Package B
Headrace tunnel D 1 53 1994 - 1996 7400 5.6 Schist and gneiss Wirt h68 Cleuson Dixence Package C
Headrace t unnel D 1 52 1994 - 1996 7400 5.8 Schist , micachist , gneiss, and quartzit e Robbins69 EOLE B 1 46199 3 - 1996 2 x 1700 7.4 Sands, marl and ' caillasse' marl/ limest one,
sandst one and limest one Voest Alpine70 Sout h-east plat eau G 146 1994 - 1997 3925 4.42 Molasse sand, moraine, alluvium NFM
out fall sewer (EPSE)71 Cadiz: Galerie Guadiaro Majaceit e F 1 48 1995 - 1997 12 200 4.88 Limest one, consolidat ed clay NFM/ MHI72 Lille met ro Line 2 Package 2 C 1 48 1995 - 1997 3962 7.68 Flanders clay FCB73 Nort h Lyons bypass,
Caluire t unnel, Nort h t ube A 1 50 1994 - 1996 3252 11.02 Gneiss, molasse, sands and conglomerat e NFM74 Nort h Lyons bypass, Caluire t unnel,
Sout h t ube A 1 50 1997 - 1998 3250 11.02 Gneiss, molasse, sand, and conglomerat e NFM75 Storebaelt rail t unnels B 150 1990 - 1995 14 824 8.78 Clay and marl Howden76 St rasbourg t ram line C 1 50 1992 - 1993 1198 8.3 Sands and grav iers Herrenknecht77 Thiais main sewer Package 1 G 154 1987 - 1989 4404 2.84 Marl and clay Lovat78 Ant ony urban area main sewer G 1 54 1 989 1483 2.84 Alluvium, limest one, marl Lovat79 Fresnes t ransit G 1 54 1 991 280 2.84 Marl and alluv ium Lovat80 Main sewer beneat h CD 67 G 154 1991 6 70 2.84 Marl Lovat
road in Ant ony81 Duplicat ion of main sewer,
Rue de la Barre in Enghien G 154 1992 - 1993 8 07 2.84 Sand, marly limest one, marl Lovat82 Bièvre int ercept or G 1 54 1 993 1000 2.84 Marl and alluv ium Lovat83 Duplicat ion of main sewer,
Ru des Espérances - 8t h t ranche G 156 1993 - 1994 1387 2.54 Limestone, sand Lovat84 Duplicat ion of main sewer,
Ru des Espérances - 9t h t ranche G 1 56 1995 - 1996 1200 2.54 Coarse limest one, marly limest one Lovat85 Duplicat ion of main sewer,
Ru des Espérances - 10t h t ranche G 1 56 1996 - 1997 4 69 2.54 Marly limest one Lovat
(APPENDIX 3)
Dat eBoredlengt h
(m)
Boreddiamet er
(m)
GeologyProject