ASSOCIATION

INTERNATIONALE DES TRAVAUX

EN SOUTERRAIN ITA
INTERNATIONAL
AITES TUNNELLING
ASSOCIATION
Towards an In Consultative Status, Category II with the
improved use United Nations Economic and Social Council
of underground http://www.ita-aites.org
Space

Topic
MECHANIZED TUNNELLING
Title
Recommendations and Guidelines for Tunnel Boring Machines (TBMs)
Author
ITA WG Mechanized Tunnelling
published
in "Recommendations and Guidelines for Tunnel Boring Machines (TBMs)",
pp. 1 - 118, Year 2000
by ITA - AITES, www.ita-aites.org
Working Group: WG 14 - "Mechanized Tunnelling"
Open Session, Seminar, Workshop: -
Others: Recommendations

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.

Secretariat : ITA-AITES c/o EPFL - Bât. GC – CH-1015 Lausanne - Switzerland

Fax : +41 21 693 41 53 - Tel. : +41 21 693 23 10 - e-mail : secretariat@ita-aites.org - www.ita-aites.org
RECOMMENDATIONS AND GUIDELINES
FOR TUNNEL BORING MACHINES (TBMs)
WORKING GROUP N°14 - MECHANIZED TUNNELLING -
INTERNATIONAL TUNNELLING ASSOCIATION

ASSOCIATION
T RIB U N E H O R S S É RIE
M AI 2001 - IS S N 1267-8422
INTERNATIONALE DES TRAVAUX
EN SOUTERRAIN ITA
AITES INTERNATIONAL
TUNNELLING
ASSOCIATION
 International Tunnelling Association
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© International Tunnelling Association. All rights reserved. No part of this publication may be
distributed and/or reproduced, stored in a retrieval system or transmitted in any form or by any
means, electronic, mechanical, photocopying, recording or otherwise , without the prior written
permission of publisher, International Tunneling Association
 Preface
This report contains four individual reports prepared by ITA Working Group No. 14 (“Mechanized
Tunneling”). 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.

Shoji Kuwahara
Tutor, Working Group No. 14
International Tunnell i n g Association
 GENERAL CONTENTS

I. GUIDELINES FOR SELECTING TBMS FOR SOFT GROUND

by Japan and Norway

1 Classification of tunnel excavation machine

2 Investigation of existing conditions and applicability of TBM
3 Tunnel boring machine (TBM)
4 Tunnels constructed by TBM in Japan
APPENDIX: TBM Performance in hard rock

II. RECOMMENDATIONS OF SELECTING AND EVALUATING

TUNNEL BORING MACHINES
by Germany, Switzerland and Austria

1. Purpose of the recommendations

2. Geotechnics
3. Construction methods for mined tunnels
4. Tunneling machines TM
5. Relationship between geotechnics and tunneling machines

III. GUIDELINES FOR THE SELECTION OF TBMS

by Italy

1. Classification and outlines of tunnel excavation machines

2. Conditions for tunnel construction and selection of TBM tunneling method
3. References

IV. NEW RECOMMENDATIONS ON CHOOSING MECHANIZED

TUNNELLING TECHNIQUES
by France

1. Purpose of these recommendations

2. Mechanized tunnelling techniques
3. Classification of mechanized tunneling Techniques
4. Definition of the different mechanized tunnelling techniques classified in chapter 3
5. Evaluation of parameters for choice of mechanized tunneling techniques
6. Specific features of the different tunneling techniques
7. Application of mechanized tunneling techniques
8. Techniques accompanying mechanized tunneling
9. Health & Safety
 Japan and Norway

Guidelines for Selecting TBMs

for Soft Ground

ITA Working Group No. 14

Mechanized Tunneling
PREFACE

Tunnels are playing an important role in the development of urban infrastructures. Several
construction 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 Tunnel
Boring Machine (TBM). This report focuses on tunneling by TBM and is prepared to offer
guidelines and recommendations for selecting types of TBMs for urban tunnel construction. Its
main purpose is to help project owners, contractors and manufacturers evaluate the applicability and
capability 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 a
comprehensive international “manual” for TBM tunneling methods. As the contents of this report
represent Japanese and Norwegian versions of the subject, they may be revised or supplemented as
necessary 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 Working
Group and the other is for the TBMs in hard rock prepared by Norwegian Working Group. The
Norwegian 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 diameter
tunneling 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 been
primarily aimed at mechanization and automation of tunnel boring under various geological
conditions, with the combined technologies of soil, mechanic and electronic engineering. The
technological 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 international
manual for TBMs and will further contribute to the development of tunneling technologies.

I-ii
 CONTENTS

1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINE ...............................................................................1

1.1 Mechanical Excavation Type (Fig. 1.3) ...................................................................................................................3
1.2 Earth Pressure Balance (E.P.B.) Type (Fig. 1.4).....................................................................................................3
1.3 Slurry Type (Fig. 1.5) .................................................................................................................................................4
2 INVESTIGATIONS OF EXISTING CONDITIONS AND APPLICABILITY OF TBM....................................5
2.1 Site Investigations........................................................................................................................................................5
2.1.1. Existing site conditions ....................................................................................................................................5
2.1.2. Existing structures and utilities .......................................................................................................................5
2.1.3. Topography and geology..................................................................................................................................5
2.1.4. Environmental impact.......................................................................................................................................5
2.2 Applicability of TBMs ...............................................................................................................................................5
3 TUNNEL BORING MACHINE (TBM) ......................................................................................................................8
3.1 Machine Specifications ..............................................................................................................................................8
3.1.1. Essential parts of TBM.....................................................................................................................................8
3.1.2. Structure of TBM ..............................................................................................................................................8
3.1.3. Types of TBMs for soft ground.......................................................................................................................9
3.1.4. Selection of TBM..............................................................................................................................................9
3.2 Orientation and operation of machine................................................................................................................... 12
3.2.1. Excavation Control System .......................................................................................................................... 12
3.2.2. Direction Control and Measurement System ............................................................................................. 12
3.3 Cutter Consumption................................................................................................................................................. 12
3.3.1. Bit types and Arrangement ........................................................................................................................... 12
3.3.2. Wear of Bit...................................................................................................................................................... 12
3.3.3. Long Distance Excavation ............................................................................................................................ 12
3.4 Ground Support and Lining.................................................................................................................................... 13
3.4.1. Design of Lining............................................................................................................................................. 13
3.4.2. Types of Segment........................................................................................................................................... 13
3.4.3. Fabrication of Segment.................................................................................................................................. 14
3.4.4. Erection of Segments..................................................................................................................................... 15
3.5 Auxiliary Facilities................................................................................................................................................... 16
3.5.1. Earth pressure balance type machine .......................................................................................................... 16
3.5.2. Slurry type tunneling machine ..................................................................................................................... 17
4 TUNNELS CONSTRUCTED BY TBM IN JAPAN ............................................................................................... 17
4.1 Soft ground tunneling in Japan .............................................................................................................................. 17
4.2 Types of TBMs and ground conditions................................................................................................................. 18
4.2.1. Soil Conditions and Types of TBMs ........................................................................................................... 18
4.2.2. Groundwater pressure and Type of TBMs.................................................................................................. 19
Max. Size of Gravel and TBM Type ......................................................................................................................... 20
4.3 Size of TBM.............................................................................................................................................................. 21
Weight............................................................................................................................................................................. 21
Length/Diameter (L/D) ................................................................................................................................................ 21
APPENDIX: TBM PERFORMANCE IN HARD ROCK .............................................................................................. 22
A-1 General......................................................................................................................................................................... 22
A-2 Advance ....................................................................................................................................................................... 22
A-2.1 Rock Mass Properties........................................................................................................................................ 22
A-2.2 Machine Parameters........................................................................................................................................... 24
A-2.3 Other Definitions................................................................................................................................................ 26
A-2.4 Gross advance rate............................................................................................................................................. 28
A-2.5 Additional Time Consumption ......................................................................................................................... 29
A-3 Cutter Consumption ................................................................................................................................................... 30
A-4 Troubles and Countermeasures................................................................................................................................. 32
A-4.1 Causes for Trouble............................................................................................................................................. 32
A-4.2 Countermeasures ................................................................................................................................................ 33

I-iii
 FIGURES

FIG. 1.1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINES ........................................................................1

FIG. 1.2 TUNNEL EXCAVATION MACHINES .........................................................................................................2
FIG. 1.3 MECHANICAL EXCAVATION TYPE TUNNELING MACHINE ....................................................................3
FIG. 1.4 EARTH PRESSURE BALANCE TYPE TUNNELING MACHINE ...................................................................4
FIG. 1.5 SLURRY TYPE TUNNELING MACHINE ...................................................................................................4
FIG. 3.1 COMPONENTS OF TUNNELING MACHINE ..............................................................................................8
FIG. 3.2 TYPE OF TBM FOR SOFT GROUND.......................................................................................................9
FIG. 3.3 FLOW CHART FOR SELECTING TBM FOR SOFT GROUND..................................................................10
FIG. 4.1 TUNNELS DRIVEN BY TBMS IN JAPAN ...............................................................................................17
FIG. 4.2 SOIL CONDITIONS AND TYPE OF TBMS .............................................................................................18
FIG. 4.3 GROUNDWATER PRESSURE AND TYPE OF TBMS ...............................................................................19
FIG. 4.4 GRAVEL SIZE AND TYPE OF TBMS ....................................................................................................20
FIG. 4.5 DIAMETER AND WEIGHT OF TBM (EPB, SLURRY)............................................................................21
FIG. 4.6 DIAMETER AND LENGTH/DIAMETER (L/D) OF TBM ..........................................................................21
FIG. A.1 RECORDED DRILLING RATE INDEX FOR VARIOUS ROCK TYPES ........................................................22
FIG.A.2 RECORDED CUTTER LIFE INDEX FOR VARIOUS ROCK TYPES .............................................................23
FIG. A.3 FRACTURE CLASSES WITH CORRESPONDING DISTANCE BETWEEN PLANES OF WEAKNESS ..............23
FIG. A.4 RECORDED DEGREE OF FRACTURING FOR VARIOUS ROCK TYPES .....................................................24
FIG. A.5 FRACTURING FACTOR, CORRECTION FACTOR FOR DRI≠49..............................................................24
FIG. A.6 RECOMMENDED MAX. GROSS AVERAGE PER DISC.............................................................................25
FIG. A.7 CUTTERHEAD R.P.M. AS FUNCTION OF TBM-DIAMETER ...................................................................25
FIG. A.8 BASIC PENETRATION FOR CUTTER DIAMETER = 48.3 MM AND CUTTER SPACING = 70 MM ..............26
FIG. A.9 CORRECTION FACTOR FOR CUTTER DIAMETER≠483 MM ..................................................................27
FIG. A.10 CORRECTION FACTOR FOR AVERAGE CUTTER SPACING≠70 MM......................................................27
FIG. A.11 CUTTING CONSTANT CC AS A FUNCTION OF CUTTER DIAMETER ....................................................28
FIG. A.12 MAINTENANCE AS FUNCTION OF NET PENETRATION RATE..............................................................29
FIG. A.13 BASIC CUTTER RING LIFE AS FUNCTION OF CLI AND CUTTER DIAMETER.......................................31
FIG. A.14 CORRECTION FACTOR FOR CUTTING RING LIFE .............................................................................31
FIG. A.15 CORRECTION FACTOR FOR CUTTING RING VS. QUARTZ CONTENT .................................................32

I-iv
 TABLES

TABLE 2.1 COMPARISON OF EXCAVATION METHODS.............................................................................................................6

TABLE 2.2 APPLICABILITY OF TBMS TO SOFT GROUND CONDITIONS ...............................................................................7
TABLE 3.1 RELATIONSHIP BETWEEN CLOSED TYPE TUNNELING MACHINE AND SOIL CONDITIONS .......................... 11
TABLE 3.2 LOADS ON SEGMENTS ......................................................................................................................................... 13
TABLE 3.3 ALLOWABLE STRESSES OF CONCRETE FOR PRE-FABRICATED CONCRETE SEGMENTS ................................. 14
TABLE 3.4 TYPICAL DIMENSIONS OF SEGMENTS (MM)..................................................................................................... 15
TABLE 3.5 AUXILIARY FACILITIES ........................................................................................................................................ 16
TABLE 4.1 TBMS IN SOFT GROUND PERFORMED IN JAPAN ............................................................................................... 17

I-v
1 CLASSIFICATION OF TUNNEL For tunneling through sedimentary soil,
EXCAVATION MACHINE tunnel face is stabilized by breasting,
pneumatic pressure or other supporting means.
Tunnels are constructed under many types of Closed type- tunneling machine was
geological conditions varying from hard rock developed, which utilizes compressed air to
to very soft sedimentary layers. Procedures stabilize tunnel face. The closed type-machine
commonly taken for tunneling are excavation, started to dominate for soft ground tunneling,
ground support, mucking and lining. Variety especially in the countries where many tunnels
of construction methods have been developed are driven through sedimentary soil layers.
for tunneling such as cut and cover, drill and
blast, submerged tube, push or pulling box, and Tunnel excavation machines can be classified
by the use of tunnel boring machine (TBM). by the methods for excavation (full face or
partial face), the types of cutter head (rotation
TBM was first put into practical use for mining or non-rotation), and by the methods of
of hard rock, where the face of the tunnel is securing reaction force (from gripper or
basically self-standing. For tunneling through segment). Several types of tunnel excavation
earth, open type machine was used, in which a machines are illustrated in Fig. 1.1 and Fig.
metal shield was primarily used for protective 1.2,
device for excavation works.

Fig. 1.1 Classification of Tunnel Excavation Machines

I-1
1.1 Mechanical Excavation Type (Fig. 1.3) density slurry mix. The face of the tunnel is
supported by the pressurized slurry mix
The mechanical excavation type-tunneling injected into a space between its cutter head
machine is equipped with a rotary cutter head and a watertight steel bulkhead. It consists of
for continuous excavation of tunnel face. the following four components:
There are two types of cutter heads; one is the i) A cutter head for excavating the
disk type and the other is the spoke type (rod ground
style radiating from the center). The disk type ii) A slurry mixer for mixing the
is suitable for large cross section tunnels excavated muck with high-density slurry
where tunnel face is stabilized by the disk iii) Soil-discharging devise for removal
cutter head. This type of machine is capable of the muck
of excavating soils containing gravel and iv) Pressure controlling devise for
boulders with the openings in the disk, which keeping the pressure of slurry-soil mix
are adjustable according to the size of gravel steady
and boulders. The spoke type is frequently
used for small cross section tunnels where the The earth pressure balance type is classified
tunneling face is relatively stable. Gravel and into two types by the additives injected to
boulders are removed by the rotating spoke convert the excavated muck into high-density
cutter. slurry. One is earth pressure type and the
The mechanical excavation type-tunneling other is high-density slurry type.
machine is suitable for the diluvial deposit
that has a self-standing face. Application of (1) Earth pressure type
this type of machine to the alluvial deposits, Earth pressure type machine cut the ground
which usually do not form a self-standing with a rotary cutter head. Clay-water slurry
face, requires one or more supplementary is injected into the cutter chamber and is
methods such as pneumatic pressure, mixed with excavated muck. The slurry mix
additional de-watering, a n d chemical is pressurized to stabilize the tunnel face and
grouting. create the driving force of the machine. The
excavated muck is later separated from the
Hopper slurry and discharged by a screw conveyor.
This type is suitable for clayey soil layers.
Cutter driving mo
(2) High-density slurry type
High-density slurry type machine cut the
ground with a rotary cutter head. The
excavated muck is mixed with clay-water
slurry. by the rotating cutter. Highly plastic
Belt conveyo and dense additive is added to the slurry mix
in the cutter chamber. The additives are
used to increase the fluidity and to reduce
the permeability of the soil. The high-
Cutter head density slurry mix stabilizes the tunnel face.
The excavated muck is discharged by a
Fig. 1.3 Mechanical Excavation Type screw conveyor. This type is suitable for
Tunneling Machine sand or gravel layers.

1.2 Earth Pressure Balance (E.P.B.) Type

(Fig. 1.4)

Earth pressure balance type tunneling

machine converts excavated soil into high-

I-3
 Cutter head Cutter head Cutter driving motor
Cutter driving motor

Additives Slurry feed pipe

Bulkhead

Slurry discharge
Screw conveyor

Cutter chamber
Mixing wingCutter chamber

Fig. 1.4 Earth Pressure Balance Type Fig. 1.5 Slurry Type Tunneling Machine
Tunneling Machine

1.3 Slurry Type (Fig.1.5)

Slurry type tunneling machine cut the ground

with a rotary cutter head. The cutter chamber
is filled with pressurized slurry mix to
stabilize the face of the tunnel. The slurry
mix is circulated through pipes to transport it
to a slurry treatment plant where the
excavated muck is separated from slurry mix.
The excavated muck is discharged through
pipes and the slurry is circulated back to the
cutter head for re-use. The slurry type
machine consists of the following three
components:
i) A rotating cutter head for
excavating ground
ii) A slurry mixer for the production of
slurry mix with desired density and
plasticity
iii) Slurry pumps to feed/discharge,
circulate and to pressurize slurry mix
iv) Slurry treatment plant to separate
excavated muck from slurry

I-4
 i) Topography
2 INVESTIGATIONS OF EXISTING ii) Geological structure
CONDITIONS AND iii) Ground conditions
APPLICABILITY OF TBM iv) Groundwater

2.1 Site Investigations 2.1.4. Environmental impact

Environmental impact analysis of the tunnel
Site investigations are conducted to obtain construction should be carried out to select
basic data necessary for determining the and design construction methods that
project scale, selection of a tunnel route and minimize the environmental impacts to the
its alignment, applicability of TBMs, and its existing ecosystem.
environmental impact, and for planning, i) Noise and vibration
designing and construction of TBM tunnels. ii) Ground movement
Results of the investigations are also used for iii) Groundwater
operation and maintenance of TBM. The iv) Oxygen deficient air and hazardous
major items of investigation are indicated in gas such as methane gas
the following subsections. v) Chemical grouting
vi) Discharge of excavated muck
2.1.1. Existing site conditions
Existing site conditions along the proposed 2.2 Applicability of TBMs
tunnel route are investigated to survey the
following site conditions Three types of excavation methods, drilling
i) Land use and related property rights and blasting, TBM for hard rock, and TBM
ii) Future land use plan for soft ground, are compared in terms of
iii) Availability of land necessary for tunnel dimensions, geological conditions and
construction environmental impacts, and are shown in
iv) Traffic and the type of the roads Table 2.1. The shaded portions of this table
v) Existing rivers, lakes and ocean indicate the application of TBMs for soft
vi) Availability of power, water and ground.
sewage connections Among the soft ground TBMs, the mechanical
Results of the investigation are mainly used excavation type, earth pressure balance type
for determining the tunnel route, its and slurry type is compared in Table 2.2 in
alignment, locations and areas of access terms of their applicability to various types of
tunnels and temporary facilities. soft ground. This table also indicates the
items that should be taken into consideration
2.1.2. Existing structures and utilities when applying TBM to soft ground. .
Existing structures and utility lines near the As indicated in Table 2.2, earth pressure
tunnel are investigated for their future balance and slurry types are suitable for
preservation and for securing the safety of alluvial deposits that generally are not self-
TBM tunneling. standing. Slurry type is effective for driving
i) Existing surface and underground through grounds with high groundwater
structures pressure, such as those under river or seabed
ii) Existing utilities because the stability of tunnel face can be
iii) Wells in use and abandoned maintained by properly mixed and pressurized
iv) Remains of removed structures and slurry mix. On the other hand, earth pressure
temporary structures balance type is not suitable for grounds with
high groundwater pressure because it is
2.1.3. Topography and geology difficult to maintain the pressure balanced
Topographical and geological conditions are against ground water pressure due to the
the most important factors affecting the TBM opening for the soil discharging screw
design and construction. In particular, the conveyor.
following items should be investigated by
field survey, boring, etc.

I-5
 Table 2.1 Comparisonof Excavation Methods

Excavation Method TBM

Drilling and Blasting
For Hard Rock For Soft Ground
Conditions
Equipment cost is relatively low. The cost of tunnel boring machines is The cost of tunnel boring machines is
tunnel length Excavation cost is not greatly generally high. It is suitable in longer generally high. It is suitable in longer
influenced by the tunnel length. tunnel excavations. tunnel excavations.
Basically, the shape of excavation has Basically, the shape of the excavation Basically, the shape of the excavation
Tunnel an arched shape at the crown. is a circle. is a circle.
shape of the cross
Features The shape of the section can be After boring, other shapes are Semicircle, multi-circle, voal etc. are
section
changed during the construction. possible using drilling and blasting as also possible using special tunneling
the result of enlargement. machines for excavation.
2
Generally, it is possible up to 150m. The largest record is approximately The largest record is approximate ly
size of the cross
The largest record is bigger than 12m for the maximum diameter of the 14m for the maximum diameter of the
section
200m2. tunnel. tunnel.
Suitable Suitable except for the extra-hard rock Not applicable
hard rock
(s>200MPa)
Suitable Suitable Not applicable
semi-hard rock
Geological Various countermeasures become It is not suitable in area where weak Applicable
Weak layers such
Conditions necessary. ground or water inflow will be See Table.2.2
as fractured zones
frequently encountered.
and aquifer zones
Not applicable Not applicable Most suitable
Soil
See Table 2.2
Due to noise and vibration, it is not Compared to the drilling and blasting There is less effect of noise and
suitable in the vicinity of houses and there is less effect of noise and vibration to the houses and important
Environmental Noise and important structures. vibration to the houses and important structures than other xecavation
Conditions Vibration A supplementary method is necessary structures. methods.
to reduce the effects of noise and
vibration.

I-6
 Table2.2 Applicability of TBMs to SoftGround Conditions

TBM type water content Open type Closed type

N-value or Earth pressure balance type
Ground condition permeability Mechanical excavation type Slurry type
Earth pressure type High-density slurry type
Alluvium clay -Difficulty In extremely
-Difficulty in extremely weak clay
-Face stability weak clay -Earth pressure is more -Slurry spouting on
0– 5 300%– 50% s l _ s
-Ground settlement -Volume control of suitable. surface
discharged soil -Increase of secondary
slurry treatment plant
Diluvium clay -Existenceof water -Liquidity of soil
-Earth pressure is more -Increase of secondary
7 – 20 W < 50% l bearing sand l -Volume control of _ l
suitable. slurry treatment plant
-Blockage in slit chamber discharged soil
Soft rock -Earth pressure with
-Existenceof water
(mudstone) slurry is more suitable -Suitable when there is -Suitable when there is
> 50 W < 20% l bearing sand _ _ _
when there is water water bearing sand water bearing sand
-Wear of cutter bits
bearing sand.
Loose sand -Highly-advanced
10-2 – 10-3 - Contents of fine -Highly-adv
anced excavation control
5 – 30 x -Unstable face s l l
(cm/s) particles excavation control -Quality control of
slurry solution
Dense sand -Face stability
10-3 – 10--4 - Contents of fine -Wear of cutter bits -Quality control of
> 30 s -Groundwater level, s l l
(cm/s) particles -Dosage of additives slurry solution
permeability
Sand gravel -Running away of slurry
-Face stability
100 – 10-2 - Contents of fine -Wear of cutter bits -Gravel crusher
> 30 s -Groundwater level, s l l
(cm/s) particles -Dosage of additives -Fluid transportation
permeability
system
Sand and gra
vel - Contents ofine
f particles
-Face stability -Wear of cutter bits -Running away of slurry
With boulders 0 -1 -Wearof cutter bits and fac
10 – 10 -Boulder crusher -Boulder crusher -Boulder crusher
> 50 x s -Boulder crusher l s
(cm/s) -Wear of cutter bits -Boulderdiameter for -Fluid transportation
-Boulder diameter for
and face screw-conveyer system
screw-conveyer
Applicabilityfor ground It is impossible to change Applicable Applicable Applicable
Condition changes excavation system. Additive injection equipment In general,it is widely In general, It is widely
becomes necessary . applicable for various soil applicable for various soil
conditions. conditions.
Note: l Applicable, s Considerationrequired x Not applicable
Itemsto considerwhenapplying
In caseof x, reasonsfor not applicable
I-7
3 TUNNEL BORING MACHINE
(TBM) In case of the closed type machine, hood and
girder portions are separated by a bulkhead.
3.1 Machine Specifications The soil excavated by the cutter head is taken
into the mucking device through the hood
3.1.1. Essential parts of TBM portion. In some cases, man-lock is installed
TBMs are normally manufactured in drum- at the bulkhead in order to change the cutter
shaped steel shield equipped inside with bits or to remove obstacles under the
excavation and segment erection facilities. pneumatic pressure.
The essential parts of the machine include the
following items: For manual type, breasting is provided at the
i) Rotary cutter head for cutting the hood portion. The reaction force is supported
ground by the girder portion where the thrusting
ii) Hydraulic jacks to maintain a devices are installed.
forward pressure on the cutting head The tail portion of the machine is equipped
iii) Muck discharging equipment to with erector of the segments. Tail seal for
remove the excavated muck water stop is inserted between the skin plate
iv) Segment election equipment at the and the segment ring.
rear of the machine In case of the articulating system, the girder
v) Grouting equipment to fill the voids portion is made flexible by dividing the
behind the segments, which is created by portion into two or more bodies with pins and
the over excavation. jacks. Such flexible separation of the body is
adopted to allow a smooth turn along the
3.1.2. Structure of TBM curved alignment of the tunnel with different
TBM is composed of the steel shell (so called diameters of the machines, degrees of
the shield) for protection against the outer allowance of over cutting and under various
forces, equipment for excavation of soil and soil conditions,.
for the installation of the lining at the rear. When two tunneling machines are connected
The power and control devices are mounted underground, the alignments and the relative
partly or totally on the trailing car behind the positions of the two machines have to be
machine, depending on the size and structure carefully monitored and adjusted. The final
of the machine. Steel shell, made of the skin connection normally requires some soil
plate and stiffeners, is composed of three improvement work such as ground freezing,
portions; hood, girder and tail portion (see or else with extendable cutter head or hood
Fig. 3.1). equipped on either one of the machines.

Fig. 3.1 Components of Tunneling Machine

I-8
 3.1.3. Types of TBMs for soft ground TBMs such as the open type, blind type,
As described in the previous section, TBMs manual type, and half-mechanical type were
for soft ground are classified into three types; used for soft ground. The open type TBM is
earth pressure type, slurry type and now mostly replaced by closed type for soft
mechanical type. These three types of TBMs ground tunneling.
are summarized in Fig 3.2. Before those
three types were developed, other types of
(Tunnel face stabilization)
Earth pressure Excavate soil + face plate
Earth pressure type Excavate soil + spoke
High-density slurry plate stabili
Excavate soil +ing
additives + face plate
Closed
Excavate soil + additives + spoke
Slurry type Slurry + face plate
TBM stabilizing
Slurry + spoke
Partially open Blind type Bulkhead
Manual Hood
Open
Breasting
Fully open Half mechanical Hood
Breasting
Mechanical Face plate
Spoke

Fig. 3.2 Type of TBM for Soft Ground

3.1.4. Selection of TBM the type of machine. Particularly, the degree of

Careful and comprehensive analysis should be consolidation of the ground and the size of
made to select proper machine for soft ground gravel and boulders in the soil should be
tunneling taking into considerations its thoroughly investigated. Table 3.1 shows the
reliability, safety, cost efficiency and the general relationship between the closed type of
working conditions. In particular, the tunneling machine and soil conditions. In a
following factors should be analyzed: case where a tunnel is very long or is under
i) Suitability to the anticipated complex geological conditions, uniform layers
geological conditions could not be expected throughout the entire
ii) Applicability of supplementary length of the tunnel. In such case, a tunneling
supporting methods, if necessary method is selected based on the geological
iii) Tunnel alignment and length condition prevailing throughout the tunnel.
iv) Availability of spaces necessary for Special attention should be paid to the
auxiliary facilities behind the machine and following local geological conditions:
around the access tunnels i) Soft clayey soil that is sensitive and easy to
v) Safety of tunneling and other related collapse
works. ii) Sand and gravel layers with high water
contents
iii) Layers which contain boulders
Fig. 3.3 indicates a flow chart for selecting iv) Layers which may contain driftwood or
TBM for soft ground. In selecting the type of ruins
TBM, it is important to consider geological and v) Strata which are composed of both soft and
groundwater conditions that affect the stability hard layers
of the tunnel face.
Geological condition along the tunnel route is Slurry type is easy to be automatically
a primary factor to be considered for selecting controlled and is the most advanced excavation

I-9
method for soft ground tunneling because of its and arrival area where the face of the tunnel is
reliability, safety and the minimum disturbance difficult to be stabilized. Also, some
to surrounding ground. supplementary methods such as chemical
Both earth pressure balance type and slurry grouting, ground freezing, pneumatic pressure
type generally does not require supplementary and boulder crushing are required to drive
supporting methods under ordinary conditions. through grounds with boulders or gravel, under
The supplementary methods should be thin overburden or any other special conditions.
considered, however, for tunneling at starting

Preliminary Investigation
Site Investigation
Geology,

Investigation for Route Selection

Conditions of the Plan, Geological Conditions, Conditions of Construction, etc.

Investigation for Construction

Face Stability, Ground Settlement, Environmental Preservation, etc.

Face

Basic Investigation
Yes No

Earth Pressure Balance Type

Mechanized Excavation Type Slurry Type

Investigation of Ground Settlement

Investigation of Additional Countermeasures

Detailed Investigation

Comparison of TBM Type

Selection of Construction Method

Selection of TBM Type

Fig. 3.3 Flow Chart for Selecting TBM for Soft Ground

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 Table 3.1 Relationshipbetween Closed Type Tunneling Machine and Soil Conditions

Type of machine Earth pressure balance type

Slurry type
N-value Earth pressure type High-densityslurry type
Soil conditions Suitability Check point Suitability Check point Suitability Check point
Mold 0 x _ s settlement s Settlement
Alluvial Silt, Clay 0–2 l _ l _ l _
clay Sandy silt 0–5 l _ l _ l _
Sandy clay 5 – 10 l _ l _ l _
Jamming by
Loam, Clay 10 – 20 s l _ l _
Diluvial excavated soil
clay Sandy loam 15 – 20 s ditto l _ l _
Sandy clay Over 25 s ditto l _ l _
Solid clay
Solid clay Over 50 s ditto s Wear of bit s Wear of bit
( muddy pan)
Sand with silty clay 10 – 15 l _ l _ l _
Content of clayey
Sand Loose sand 10 - 30 s l _ l _
soil
Compact sand Over 30 s ditto l _ l _
Loose gravel 10 – 40 s ditto l _ l _
High water
Compact gravel Over 40 s l _ l _
Gravel pressure
Cobble Gravel with cobble Jamming of screw
_ s l _ s Wear of bit
stone stone conveyor
Large gravel
_ s Wear of bit s Wear of bit s Crushing device
Cobble stone
l :normallyapplicable s:applicablewith supplementarymeans x :not suitable

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3.2 Orientation and operation of machine jack, a mathematical theory of “fuzzy control
theory” has been applied based on the date
3.2.1. Excavation Control System accumulated through the past performance of
Since the closed type machine was developed, the machine. Recent automatic direction
tunnel excavation has been mostly controlled control system realizes accuracy of plus or
by computerized system rather than manually. minus 30 mm both horizontally and vertically.
In addition, various supporting systems
necessary for tunneling operation require 3.3 Cutter Consumption
sophisticated controlling system. A real time
computerized system equipped with various 3.3.1. Bit types and Arrangement
sensors is developed for tunneling, in which There are several types of bits for TBM, such
orientation and operation of machine, as teeth bit, peripheral bit, center bits, gouging
excavation, backfill grouting and operation of bit, wearing detection bit, etc. Bits are
auxiliary facilities are controlled by a generally made by steel or hard chip alloy that
centralized computer system. The system is highly wear resistant. Selection of material
realized accurate alignment, excavation control and types of bits is made based on the ground
that maintains the stability of the face of the conditions, excavation speed and
tunnel, and minimized the disturbance of the length of the tunnel. Arrangement of bits
surrounding ground. For slurry type tunneling on the cutter head is decided based on
machine, operation of pumps and valves for construction conditions, past experience
slurry transportation is computerized based on in similar geology, cutting depth and the
the data fed by pressure gauges, flow meters number of passes of rotating bits.
and other measuring devices for fluid
transportation. Thus, steady pressure of slurry 3.3.2. Wear of Bit
is maintained throughout the tunneling Generally, the amount of wear of bits is
operation. proportional to the product of number of passes
of rotating bits and length per pass, and is
In the near future, all operation of the machine influenced by ground conditions and other
will be entirely controlled by computerized factors such as type of machine, geology,
system from above ground. material and arrangement of the bits on a cutter
head. The amount of wear can be estimated by
3.2.2. Direction Control and Measurement the following formula;
System
Automatic direction control system has been d =(K.π.D.N.L)
put to practical use that utilizes survey data here, d: amount of wear (mm)
obtained by real time measurement device K: wear coefficient (mm / km)
instead of the conventional transit-level survey. D: distance between the center of cutter
The system consists of measurement and disk and bit (m)
direction control systems, and comprises of N: number of revolution of cutter disk per
four functions; survey, monitor, analysis and minute (rpm)
control. The measurement system utilizes laser L: excavation distance (m)
beam (laser, infrared or diode) or gyrocompass, V: rate of excavation (mm / min)
and measures the location of the machine in
three-dimensional coordinates and its attitude The wear coefficient, K, above is given by
(pitching, rolling and yawing). manufacturers based on the pressure applied to
bits, the rotating speed, geological conditions,
Direction of the machine is normally controlled number of passes and material of bits to be
by jacks that introduce proper thrust force and used.
rotation moment. Each jack on a cutter disk is
controlled by a computerized system based on 3.3.3. Long Distance Excavation
the target amount of thrust and the direction of Sometimes, a tunneling machine is required to
machine. In the process of determining the drive through entire length of tunnel when
amount of thrust required for each individual access tunnels for installation of two or more

I-12
machines cannot be constructed due to the lack after the erection of segments. Therefore, the
of land available. In that case, the tunneling role of the secondary lining is mostly not
machine, especially the cutting bit and tail seal, for the main structural member, but for
is required to be highly durable. the supplementary member for water
For higher durability of the bits, new chipping proofing, anticorrosion, etc. Secondary
material such as hard chip alloy has been lining is omitted to save costs when the
developed, which are two or three times primary lining is watertight enough or the
durable than those of conventional material. ground conditions are favorable.
Bits can be changed from inside the TBM.
Durability of tail seals and the method of For the design of the segment, several loads
changing them are being improved as well. and their combination should be considered
(see Table 3.2). Temporary loads that vary
3.4 Ground Support and Lining during the construction such as thrust force by
jacks and grouting pressure should be also
3.4.1. Design of Lining taken into consideration.
The linings of the tunnel must withstand the
soil and water pressure acting on the tunnel. The effects of joints between segments and
Primary tunnel lining is usually constructed by rings should be carefully assessed when
prefabricated concrete segments erected around designing segment lining. As several segments
the periphery of the tunnel. Those segments are pieced together to produce a ring, the ring
are connected each other to form circular rings may not deform uniformly against the
which are installed side by side continuously to surrounding loads due to weakness at segment
form a cylinder. The second lining, when joints. The same can be said to the joints
required, is normally constructed by in-situ between rings. Staggered arrangement is made
concrete. to reduce these effects of the joints.

Usually primary lining is designed as a main Under present design method, segment ring
structural member against the final load, assumes to be a uniform flexural ring, a multi-
because the secondary lining is installed long hinged ring or a ring with rotational springs.
Table 3.2 Loads on Segments

Main load vertical and horizontal earth pressure

water pressure
dead load
surcharge load
ground reaction
Secondary load internal load
temporary load during execution
seismic load
special load Influences of adjacent tunnel
of adjacent structures
of ground settlement others

3.4.2. Types of Segment Reinforced concrete prefabricated segments

As the cost of segments shares significant are most commonly used for tunnels driven by
portion of total tunneling cost, type of segment TBMs. Reinforced concrete segment is an
should be carefully selected from both excellent lining member with high
engineering and economical points of view. compressive strength against both radial and
Segments are classified into several types; longitudinal forces. It also has high rigidity
reinforced concrete (RC), steel, cast iron and water tightness. On the other hand, it is
(ductile), composite, and others. heavy and has less tensile strength and more
fragile than steel ones. Therefore, extreme
care should be taken to the removal of forms

I-13
during fabrication and to the erection during various types have been used or proposed,
construction in order to avoid possible such as composite segments (steel and RC,
damages to segments, especially to their steel and plain concrete), flexible segment that
corners. Rectangular shaped segments are allows certain degree of deformation caused
commonly used, but hexagonal or other by earthquake or uneven ground settlement.
shapes are also produced. They can be either Also, there are several types of radial and
solid or box type. longitudinal segment joints such as bolt,
cotter, pin and pivot, knuckle and other joint
Steel segment is flexible and is relatively light types.
and easy in handling. Because of the
flexibility of steel segment, they should not be 3.4.3. Fabrication of Segment
subjected to high thrusting force of jacks or Fabrication of segments has to be carried out
grouting pressure to avoid buckling or under strict quality control to ensure
unnecessary deformation. When the second compliance with specified dimensions and
lining is omitted, proper anticorrosion strength. Automated fabrication of segments
measures should be taken. is desired that provide adequate quality
control to ensure structural integrity and
Cast iron (ductile) segment is produced with precise dimensions of segments.
precise dimensions and therefore can be Table 3.3 provides allowable stresses of
erected with good water tightness. Because of concrete for pre-fabricated reinforced
its strength and durability, it is commonly concrete segment.
used at locations under heavy loads or for
reinforcing tunnel openings.
Table 3.4 provides typical dimensions of
In addition to above three types of segments, steel 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 20
Shearing stress 0.71 0.73 0.74 0.76 0.77
Bonding stress to deformed re-bar 2.0 2.1 2.1 2.2 2.2
Bearing stress (overall load) 15 16 17 18 19

I-14
 Table 3.4 Typical Dimensions of Segments (mm)

Steel Segment Concrete Segment

Outer Diameter Width Thickness NO/Ring Width Thickness NO/Ring
1,800 _ 2,000 750 75 6 900 100 5
100 125
2,150 _ 2,550 900 100 6 900 100 5
1,000 125 1,000 125
2,750 _ 3,350 900 125 6 150
1,000 150
175
3,550 _ 4,050 900 125 7 900 125 6
1,000 200 1,000 150
225 175
4,300 _ 4,800 900 150 7 200
1,000 175
5,100 _ 5,700 900 175 7 900 175 6
1,000 200 1,000 200
225 225
6,000 900 200 7 250
1,000 225 275
300
6,300 _ 6,900 900 250 7 900 250 7
1,000 275 1,000 275
300
7,250 _ 8,300 900 300 8 900 275 8
1,000 325 1,000 300
350 325
350

3.4.4. Erection of Segments

The process of primary lining consists of 3.5 Auxiliary Facilities
transportation and erection of segments.
Segments are usually transported through the Generally, tunneling operation by TBM
tunnel by cars on rails. Automatic consists of cutting ground by cutter head,
transportation system of segments is used to jacking to push machine forward, muck
recent projects that transport segments from a transportation, segment erection and grouting
depot above ground to the rear end of the of voids behind segments. Auxiliary facilities
machine through access shaft and tunnel. that are typically required throughout this
operation are shown in Table 3.5.
The erection of segments is done by an Common facilities are gravel treatment plant,
erector at the rear room of the machine. The grouting facilities, segment depot and
segment erector is equipped with gripping, treatment facilities. For the discharge of
shifting, rotating and setting devices. excavated muck, different types of facilities
Longitudinal joints of segment rings are are required depending on the type of
normally made manually. tunneling machines as follows.

I-15
 3.5.1. Earth pressure balance type 3.5.2. Slurry type tunneling machine
machine Sequence of discharging the excavated muck
The excavated muck is removed from the for this type of machine consists of; (i)
cutter chamber by a screw conveyor and sent pouring slurry to the cutter chamber while the
out by mucking car or belt conveyor. For soil is excavated and the machine is pushed
small diameter tunnels where working space forward, (ii) mixing excavated soil with slurry
is quite limited, the excavated muck is mixed and pumping the slurry mix from the cutter
with plasticizer and pumped out through the chamber to a treatment plant where the slurry
pipe. For these operations, additive mixing mix is separated into soil and slurry, (iii)
plant, a screw conveyor and belt conveyor or discharging the separated soil out to the
mucking cars are required. disposal area and circulating the slurry back
to the tunnel face for reuse. Auxiliary
facilities required for these operations are
slurry mixer, feed and discharge pumps and
pipes, 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 - Slurry transport facilities, such as slurry
- Additive mixing plants pumps and pipes.
- Slurry treatment facilities, such as
centrifugal classifier and filter plant

I-16
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-21
APPENDIX: TBM PERFORMANCE IN adjustments in accordance with increased
HARD ROCK knowledge and improvements of TBMs,
auxiliaries and methods. The model is today
A-1 General considered as a practical and useful tool for
pre-calculation of time consumption and costs
The following prognosis model is a summary for TBM bored tunnels in hard rock. The
of “Project Report 1-94, Hard Rock Tunnel model is based on the use of TBM, Open type.
Boring”, published by University of
Trondheim, The Norwegian University of A-2 Advance
Science and Technology, NTH Anleggsdrift.
A-2.1 Rock Mass Properties
The prognosis model is based on job site 1. DRILLING RATE INDEX, DRI: Index
studies and statistics from 33 job sites with 230 related to the properties of the rock mass.
km of bored tunnels in Norway and other Together with Fracturing, DRI is the rock mass
countries. Data have been carefully mapped, factor that has the major influence on
systematized and normalized and the presented Penetration Rate.
results are regarded as representative for well DRI is calculated from two laboratory tests,
organized tunneling. It should be noted that - the Brittlenes Value S20
the prognosis model is valid for parameter - Sievers J-Value SJ
values in the normal range. Extreme values The two tests give measures for the rock’s
may, even if they are correct, not fit the model ability to resist crushing from repeated impacts
and give incorrect estimates. and for the surface hardness of the rock.
Recorded Drilling Rate Indexes for some rock
The prognosis model has been developed types are shown in Fig. A.1.
continuously since 1975 and has in the period
up till now been through several phases and

Fig. A.1 Recorded Drilling Rate Index for various rock types

2. CUTTER LIFE INDEX, CLI: Cutter Life CLI expresses the lifetime in boring hours for
Index is calculated on the basis of Sievers J- cutter rings of steel on TBM. Recorded CLI
Value and the Abrassion Value steel. ( AVS.) for some rock types are shown in Fig.A.2

I-22
 Fig.A.2 Recorded Cutter Life Index for various rock types

3. FRACTURING: The most important a) JOINTS in this respect are fractures that can
penetration parameter for tunnel boring. In this be followed all around the tunnel profile.
context, fracturing means fissures and joints b) FISSURES are non-continuous fractures
with little or no shear strength along the planes which can be followed only partly around
of weakness. The less the distance between the the tunnel profile.
fractures is, the greater the influence on the c) FRACTURING is recorded in CLASSES
penetration rate. Rock mass fracturing is with reference to the distance between the
characterized by degree of fracturing (type and planes of weakness. The classes are shown in
spacing) and the angle between the tunnel axis Fig. A.3. Recorded fracturing for some rock
and the planes of weakness. types are shown in.

Fig. A.3 Fracture classes with corresponding distance between planes of weakness

I-23
 Fig. A.4 Recorded degree of fracturing for various rock types

d) FRACTURING FACTOR, Ks combines the e) EQUIVALENT FRACTURING FACTOR

effect of the fracturing class and the angle expresses the rock mass properties as the
between tunnel axis and planes of weakness. Fracturing Factor Ks adjusted for DRI-value.
See Fig.A.5. The factor Ks is used in a See Fig.A.5. KEQV = Ks x KDRI
formula for calculation of penetration rate.

Fig. A.5 Fracturing factor, Correction factor for DRI≠49

I-24
A-2.2 Machine Parameters between TBM and rock mass is disregarded.
1. BASIC CUTTER THRUST: (MB) The gross Recommended max. gross average thrust for
thrust of the TBM divided by number of TBMs with different diameters and cutter
cutters, N. Thus, for practical calculating diameters are shown in Fig. A.6. For
purpose the CUTTER THRUST in this model calculation of penetration the cutter diameter
means the average thrust of all the cutters on and cutter spacing must be taken into account.
the cutter head (kN/cutter). The friction

Fig. A.6 Recommended max. gross average per disc

2. CUTTER SPACING: The average Minute. Cutter head r.p.m. is inverse

distance between the cutter tracks on the face = proportional to the cutter head diameter. This is
Diameter of TBM /2N (N= number of in order to limit the rolling velocity of the
cutters)._CUTTER SPACING is normally peripheral cutters. Cutter head r.p.m. as
about 70 mm. function of TBM diameter is shown in Fig. A.7.
3. CUTTER HEAD R.P.M.: Revolutions per.

Fig. A.7 Cutterhead r.p.m. as function of TBM-diameter

I-25
 A-2.3 Other Definitions
1. BASIC PENETRATION RATE: Basic
4. INSTALLED POWER ON CUTTER Penetration Rate (i) in mm/rev as a function of
HEAD: (kW) The rated output of the motors equivalent thrust and equivalent fracturing
that are installed to give the cutter head its factor is shown in Fig. A.8. For cutter
torque. The rolling resistance and thus the diameters and average cutter-spacing different
torque demand increases with increasing net from _=483 mm and 70 mm respectively the
penetration. The available torque may therefore equivalent thrust is given by the formula: MEQV
be the limiting factor when the penetration is = M x x KDX x KA (kN/cutter)
high and/or the TBM is boring in very Fig. A.9 and Fig. A.10 give correction factor
fractured rock. See 3) (3) TORQUE - Kd for cutter diameters different from 483 mm
DEMAND below. and factor KA for cutter spacing.

Fig. A.8 Basic penetration for cutter diameter = 48.3 mm and cutter spacing = 70 mm

I-26
 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: Net installed power on the cutterhead gives

penetration rate (I) is a function of sufficient torque to rotate the cutterhead. If not
basic_penetration and cutter head r.p.m. the thrust must be reduced until the required
I = i x r.p.m. x (60/1000) (m/hr) torque is less than the installed capacity.
3. TORQUE DEMAND: For calculated high Necessary torque is given by the following
net penetration o r when the rock formula:
is_very_fractured, one must check that the

I-27
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 Rate - Regripping TT (Depends on stroke length,

Besides limitations due to available torque, the normally 1.5-2.0 m. As an average 4-5
system’s muck removal capacity may be a minutes.)
limiting factor, particularly for large diameter - Cutter change and inspection Tc (Depends
machines. When boring through marked single on cutter ring life and net penetration rate.
joints or heavy fractured rock, it may be Time needed for cutter change may vary
necessary to reduce the thrust due to too high from 30 to 60 minutes per cutter.)
machine vibrations and very high momentary - Maintenance and service of TBM, TTBM,
cutter loads. and back-up equipment TBACK (Time
consumption for maintenance and repair
A-2.4 Gross advance rate depends on net penetration rate as
THE GROSS ADVANCE RATE is given in indicated in Fig. A.12.)
meters per week as an average for a longer - Miscellaneous TA (Miscellaneous include
period. Gross advance rate depends on net normal rock support in good rock
penetration rate, machine utilization and the conditions, waiting for transport, tracks or
number of working hours during the week. roadway, surveying or moving of laser,
Machine utilization is net boring time in water, ventilation electric cable, cleaning,
percent of the total tunneling time. Total other things like travel, change of shift
tunneling time includes: Boring TB (Depends etc.) TA as hours per km is indicated in
on net penetration rate) Fig. A.12.

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 Fig. A.12 Maintenance as function of net penetration rate

A-2.5 Additional Time Consumption Drilling Rate Index: DRI= 60

Estimation of time consumption for a tunnel is Degree of fracturing: St II
based on weekly advance rate, estimated on the Angle between tunnel axis
basis of net penetration rate and total utilization and planes of weakness: 45
of the TBM. In addition, extra time must be Fracturing factor. ks = 1.40
added for
- assembly and disassembly of TBM and
back-up equipment in the tunnel Machine parameters:
- excavation of niches, branches, dump TBM diameter: f = 4.5 m
stations etc. Cutter diameter: 483 mm
- rock support in zones of poor quality Gross thrust pr. cutter: Fig. A.6
- additional time for unexpected rock mass 290 kN/cutter
conditions Cutterhead r.p.m.: Fig. A.7
- permanent rock support and lining work 11.1 rev./min.
- downtime due to major machine Number of cutters: 32
breakdowns Average cutter spacing: 70 mm
- dismantling of tracks, ventilation, invert Installed power: 1720 kW
cleanup etc.
Net penetration rate:
Equivalent thrust: Fig. A.9 and Fig. A.10
Example of application MEQV = 290 x 1.00 x 0.975 = 283 kN/cutter
Basic penetration: Fig. A.8 i = 8.40 mm/rev
Geometrical conditions: Net penetration:
Tunnel diameter: f = 4.5 m 8.40 x 11.1 x 60/1000 = 5.59 m/hour
Tunnel length: L= 3200 m

Geological conditions:
Type of rock: Mica Schist

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Torque check:
Cutter constant: Fig. A.11
Cc = 0.034
Cutting coefficient:
kc = 0.034 x 8.400.5 = 0.0985
Necessary torque:

Necessary power:
PN = 1213 x 2π x 11.1/60 = 1410 kW

A-3 Cutter Consumption

The cutter ring life depends mainly on the

following 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, is

proportional to the Cutter Life Index. (CLI)
Fig. A.13 shows the basic cutter ring life as a
function of CLI and cutter diameter.
Corrections must be made for varying
cutterhead r.p.m. Also for TBM diameter as
Center- and Gauge Cutters have a shorter
lifetime than Face Cutters. (Fig. A.14).
Corrections must also be made for number of
cutters on TBM (Ntbm) deviating from normal
(No). Finally correction must be made to
quartz-content.(Fig. A.15)

Average life of cutter rings is thus given the

following formulas:
Cutter ring life in h/c: HH = (H0 x k f _ x k0 x
kRPM x kN)/NTBM

Cutter ring life in m/c: Hm = HH x I (I = net

penetration rate)

I-30
Fig. A.13 Basic cutter ring life as function of CLI and cutter diameter

Fig. A.14 Correction Factor for Cutting Ring Life

I-31
 Fig. A.15 Correction Factor for cutting ring vs. Quartz Content

A-4 Troubles and Countermeasures it may be even worse to TBM-tunneling

with all the sophisticated electrical
A-4.1 Causes for Trouble. installations.
<<Trouble>> is caused by unforeseen incidents Water may come from groundwater, ores,
or conditions that may be difficult to tackle leakage through the overburden from lakes,
within estimated tunneling time. Trouble in rivers etc. or even from underground lakes or
hard rock boring come from: from Artesian wells. Inflow of salt water may
- geological conditions be damaging even in small amounts and calls
- reasons related to the TBM itself and/or for special precautions.
from the rest of the machines and It creates a special atmosphere in the tunnel
installation, - and/or trouble come as a with damaging effect to the electrical
consequence of lack of experience from equipment and rust and corrosion to the steel
similar works and general know-how in construction if not taken care of.
tunneling.
1. Geological Causes b) Boring in Hard Rock means normally boring
a) Water Inflow is always a factor one shall in Sound, Solid Rock, and <<open>> TBMs
have in mind. It counts for everything are normally chosen. Nevertheless it is not
from occasional appearance of small unusual to meet Faulty Fractured Zones,
amounts of water with no practical Unconsolidated Weak Rock, Swelling Ground,
consequences, to total inundation with free Squeezing Ground and very often so called
flowing conditions, some times with Mixed Faces which means that face consists
material outwash and serious tunneling partly of hard massive rock and partly of
problems. If caught unaware, these fractured rock. Even one single significant
problems are capable of completely fracture may influence the drillability.
disrupting tunneling activity and Consequences to the boring may naturally vary
influencing the time schedules drastically. from minor problems to the penetration rate to
This is serious to conventional tunneling, - full stop with TBM stuck in the tunnel.

I-32
Swelling Ground very often comes from the costs are to a very great extent dependent on
influence of special rock materials as so called the TBM and the supplementary equipment.
swelling clay which starts swelling when The geology related conditions in a tunnel are
exposed to humidity. It may cause down-fall fixed as such. The result of the tunneling with
and dangerous conditions. Squeezing Ground respect to advance rate and tunnel-meter-cost is
is found in tunnels in soft rock with large therefore in fact a question of doing the right
overburdens, and consequently high rock choice of TBM and equipment and to be
pressure. Rock deformations may in extreme prepared for conditions as they appear.
cases lead to total closing of the tunnel.
The right choice of TBM and supplementary
c) Even if TBM- technology and –know how is equipment is not only a question of looking at
steadily improving and thus extending the machine specifications. It is also a question to
frame as far as the geology and the which extent it is possible to utilize the same
geological parameters are concerned, there machine parameters. It is an experience from
are still limits. The drillability is a function hard rock boring that the TBMs have more
of a number of rock parameters, out of power than can actually be utilized because
which fracturing and rock hardness are the components like for instance cutters in practice
most important. It is rare to get into rock are not strong enough.
which is so hard and so massive that boring Breakdowns due to Main Bearing failure or due
is technically impossible with the most to failure on other important and expensive
powerful TBMs on the market to day, but it components or parts are naturally disastrous to
may be a challenge to the economy. time schedule and costs. (To change a main
If pre-investigations reveal occurrence of rock bearing may take from four to six weeks,
with the above properties it will be a matter of provided the bearing is available.) Downtime
calculation to find out if the available TBM is caused by unskilled operation of the
able to do the job, and in case, -what will be machinery, bad maintenance and repair,
the advance rate and what will be the cost. The waiting for supply of spares, bad ventilation,
above calculation model should be used cut in power supply, waiting for muck-
carefully in this case since it is based on transport, cutter change and cutter inspection
experiences from rock with not extreme should always be encountered and as far as
properties, but it will normally be good possible be avoided or minimized.
enough. If the rock shows up unexpected
parameters one might be in trouble if the TBM A-4.2 Countermeasures
is too weak, and/or the cutters have insufficient 1. For trouble caused by water inflow there are
quality. basically two ways to go.
- To stop the water before it gets into the
d) High Temperature Ground is found in tunnel by Grouting Ahead of the Face for
different parts of the world as for instance in which purpose boring equipment has to be
the Alps, in tropical areas and/or when the installed. The equipment should be able to
tunnel goes with extreme overburden as in make a 360°funnel with at least 25 m long
mines. The temperature is seldom a real holes for grouting.
obstacle to the boring itself as long as oil is - To take care of the water when it is in the
chosen accordingly and cooling water for tunnel by Increased Drainage Capacity.
motors and cutters are available in sufficient What is the best is depending on the
quantities, but rather a challenge to the crew. amount of water and where it comes from.
If the inflow effects change in ground
e) Combustible gases like methane and dust water level and/or pressure grouting may
with high content of coal are dangerous and be required. Large inflow of water may
must be taken care of properly. cause damage to the machinery, and to the
electrical installation in particular, and
2. Machine Related Troubles protection of exposed components may be
As is understood from the above a good result required.
with respect to advance rates and tunnel-meter-

I-33
2. Countermeasures to unusual and unsound
ground depends on the actual case 4. High Temperatures in the tunnel
Rock Bolting, Fiber-reinforced Shotcrete alone In tropical areas the outdoor temperature may
or together with Rock Bolts, Grouting or in situ also be very high, at least during daytime.
Casting with Concrete or may be necessary. Cooling of the ventilation air will therefore be
The real trouble comes if the equipment is not a necessity in such areas. Together with the
built for installation of necessary equipment to cooling effect from the evaporation of the
carry out the rock support in an efficient way. flushing water it is absolutely possible to
Fractures are discontinuities in the rock mass. achieve livable temperatures.
The fractures are described by thickness,
length, distance between the fractures, 5. Combustible Gases
roughness in planes of weakness, sort of The TBM itself and supplementary machinery
materials found in the fractures, if they are and all electrical installation must be insulated
results of bedding or foliation, and strike and to prevent any explosion to come from sparkles
dip if there is a definable pattern. Fractures in or heating. Gas Detection instruments must be
the rock mass are an advantage with respect to installed.
advance rates as long as rock support is not In dimensioning of the ventilation system the
required. occurrence of gases and dust must be taken into
The above factors are strongly into the picture consideration.
in the so called Q-method which is a method to In countries where the above are frequent
define the rock mass quality with respect to occurrences there are normally very strict
stability and the need for rock support. Various regulations with regards to what to do to
classes of rock mass quality which go from prevent explosion and also what to do if the
exceptionally good to exceptionally poor will accident should happen.
require from no support at all, spot bolting, Dust with quartz appears frequently in
systematic bolting, shotcrete etc. to cast connection with hard rock boring. It is not
concrete lining. combustible, but a serious hazard to the health
if breathed for a long period. It is partly a
3. Too Hard Rock is normally a cutter-problem. ventilation matter to remove the dust from the
The cutters are spoiling and/or heavily worn working area, and partly.
and the penetration rate is reduced. Due to
frequent cutter inspections and -changes the
utility time goes down and consequently also
the Gross Advance Rate.
Great efforts are constantly made to increase
the cutter quality. Much is achieved by
improving the steel quality in the rings and by
increasing the size of the cutters and thus be
able to use bigger and better bearings.
To change the size of cutters is theoretical, but
normally not a practical solution to meet a
section of too hard rock in a tunnel.
If the <<too hard rock>> problem seems to be
permanent it is a possibility to call for a special
study of the rock in order to improve the cutter-
result and/or to call for competing suppliers of
cutters.
Cutters with tungsten-carbide inserts are
expensive, but may be the solution for a short
period. Tungsten-carbide inserted cutters can
also be used together with normal cutters in
positions that are most exposed, for instance as
gauge cutters.

I-34
 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) und
Arbeitsgruppe Tunnelbau der Forschungsgesellschaft für
das Verkehrs- und Strass enwesen
FGU Fachgruppe für Untertagbau Schweizerischer lngenieur-
und Architekten-Verein
1. Purpose of the recommendations......................................................................................................1
2. Geotechnics .........................................................................................................................................1
3. Construction methods for mined tunnels.........................................................................................2
3.1. Survey..........................................................................................................................................2
3.2. Explanation of the Construction Methods..............................................................................3
4. Tunneling machines TM....................................................................................................................5
4.1. Tunnel Boring Machines (TBM) .............................................................................................5
4.1.1. Tunnel boring machines without shields .......................................................................5
4.1.2. Tunnel boring machines with shields TBM-S...............................................................5
4.2. Shield Machines SM .................................................................................................................5
4.2.1. Shield Machines with full-face excavation SM-V........................................................5
4.2.2. Shield machines with partial axe excavation SM-T .....................................................7
4.3. Adaptable dual purpose shield machines................................................................................9
4.4. Special forms..............................................................................................................................9
4.4.1. Finger shields.....................................................................................................................9
4.4.2. Shields with multi-circular cross-sections .....................................................................9
4.4.3. Articulated shields.............................................................................................................9
4.4.4. Cowl shield ........................................................................................................................9
4.4.5. Displacement shield..........................................................................................................9
4.4.6. Telescopic Shields.............................................................................................................9
4.5. Supporting and lining ..............................................................................................................10
4.5.1. Tunnel boring machines TBM.......................................................................................10
4.5.2. Tunnel boring machines with shield TBM-S and shield machines SM ..................10
5. Relationship between geotechnics and tunneling machines.......................................................11
5.1. Ranges of application for tunneling machines.....................................................................11
5.2. Important selection and evaluation criteria ..........................................................................12
5.3. Pointers for special geotechnical and constructional conditions.......................................15

II-ii
1. Purpose of the recommendations represents the main basis for the approach.
These recommendations do not apply, or only
The developments in mined tunneling are to a certain extent for micro tunneling.
characterized by an increased trend towards
fully mechanized tunneling with appropriate
tunneling machines (TBM) in solid rock and 2. Geotechnics
soft ground. The creation of special methods
such as face supporting with fluid or slurry as The knowledge of the geotechnical conditions
well as the successful utilization of cutter discs is the most important principle for the planning
for removing rock-like intrusions and boulders and execution of a tunneling project. The
have led to a considerable expansion of the evaluation of general and special maps leads to
field of application and to an increase in the initial recognition about the geological and
economy of these tunneling systems. hydrogeological conditions and provide
The increasing application of tunneling pointers for further investigatory measures. By
machines and the related continuous means of suitable preliminary explorations, the
improvement of the various extraction nature and features of the subsoil that must be
techniques had led to types of machines, which penetrated during the construction of a tunnel
have the capacity to penetrate extremely can be described. The accuracy of this
heterogeneous subsoil, that is respectively a description depends on the type and extent of
mixture of soft ground and solid rock. The these pre-investigations as well as their
clear distinction between tunnel boring validity. Extremely variable geological
machines (TBM) for solid rock and shield conditions call for more intensive of
machines (SM) for soft ground, which resulted preliminary surveys.
from their conceptional background and the Conditions which restrict the
special engineering and extraction technology, pre-investigations lead to a limited validity of a
has lost its original significance. Past geotechnical report. This must be taken into
developments and the progress made in account when assessing the projected
practice have produced tunneling machines, in geotechnical conditions. The aim of the
which the typical features of both techniques geotechnical survey must be to present the
have been integrated in a single unit. In this geological and hydrogeological conditions
way, the possibility has been created to make required for the tunneling project as
available tunneling machines suitable for the comprehensively and lucidly as possible.
entire geotechnical spectrum. The subsoil that has to be penetrated is, by and
The anticipated geotechnical conditions in large, examined by means of:
conjunction with the course of the route and _ investigatory boreholes and the obtaining of
gradient represent the decisive prerequisites for bore samples and cores
selecting the tunneling method. By comparison _ exploration and sample-taking on the surface
of the cross-section needed for the purpose of _ dynamic penetration tests, pressure probes
the tunnel, its length and the geotechnical _ mechanical borehole examinations, e.g.
conditions with the available technology, the borehole expansion tests, pressiometer
most suitable tunneling machine can be _ geophysical investigation methods
devised. These recommendations apply to _ pump and water injection tests
inter-relationships, which exist between the _ exploratory tunnels
geotechnical circumstances and process and Through these investigations and, above all,
engineering techniques. through the samples that were taken,
When selecting tunneling machines, the characteristic values are obtained or derived
environmental compatibility of the tunneling through further suitable investigations and
methods must also be taken into consideration. corresponding evaluations.
These recommendations should also be seen as The more comprehensively the preliminary
an additional aid, designed to serve the investigations are carried out and the more
engineer in arriving at a decision. A project- valid they are the better the basis for selecting
related analysis is, however, essential and the tunneling method and the tunneling

II-1
machines. values and an overall appraisal of the
The essential geotechnical parameters are geological and hydrogeological conditions of
listed in the following: the subsoil, generally speaking, the following
extremely important technical data can be
solid rock obtained:
- compressive strength (rock strength) - ease of break-out of the subsoil
- tensile strength, cleavage strength - stability of the subsoil
- shearing strength - stability of the face
- break and bedding planes - measures for supporting the face
- degree of decomposition, degree of - nature and extent of the supporting measures
weathering - time lag between breaking-out and securing
- fault zones the subsoil
- mineralogy/petrography - deformation behavior of the subsoil
- proportions of abrasive minerals - influence of underground and/or groundwater
- wearing hardness/hardness - abrasiveness of the subsoil
- water-bearing and water pressure (under- - stickiness of the excavated soil
ground water) - separability of the excavated soil (when using
- chemical analysis of the water a supporting fluid)
- suitability for reutilization of the excavated
soft ground soil
- grain distribution curves
- angle of friction Factors, which influence the environment,
- cohesion must also be observed, such as e.g.:
- deposit thickness - surface settlements
- compressive strength - interference with and changes to
- shearing strength the groundwater conditions
- pore volume - suitability of the excavated material for
- plasticity landfill
- swelling behavior - contamination of the subsoil and groundwater
- permeability - health-jeopardizing influences
- natural and artificial intrusions and faults On the basis of the listed geotechnical
- water-bearing and water pressure (ground characteristic values and constructional data
water) including the environmentally relevant factors,
- chemical analysis of the water it is possible the select the construction method
and to divide the tunnel over its route into
special features tunneling classes, which closely define the
- primary stress state tunneling method, identify the performances to
- rock burst be applied per tunneling class and describe the
- fault zones degree of difficulty. Whereas the selection of
- weakening due to leaching processes the construction method is the prerequisite for
- heaving/swelling rock allocation into tunneling classes (laid down by
- subsidence and subsidence chimneys the client), the choice of the machine should be
- karst manifestations left open as far as possible and left up to the
- gases responsible contractor (choice of the
- rock temperature construction company).
- seismic action
More detailed information relating to
investigating the subsoil is contained in DIN 3 . Construction methods for mined
4020-Geotechnical Inve s t i g a t i o n s for tunnels
Construction Purposes. Further pointers are
contained in the “Recommendations for 3.1. Survey
Tunneling - Chapter 3: Geotechnical Different construction methods are available
Investigations” , published by the DGGT. for executing a tunnel by mining. They can be
From the cited geotechnical characteristic split up into the groups-universal headings,

II-2
mechanical headings (tunneling machines) and not drive circular cross-sections.
micro-tunnel headings. In this connection, Tunneling machines are, by and large, geared
those methods for which the extraction resp, to their diameter. This applies, first and
the cutting phase is decisive are allocated to foremost, to shield machines. In the case of
solid rock. In the case of soft ground, on the tunneling machines for solid rock, a certain
other hand, the supporting and/or securing of variation of the diameter is possible if a shield
the subsoil is accorded priority(Fig.1). body is not required.
In conjunction with the special demands Recent developments allow shield machines to
placed on a tunnel and taking environmental be modified for different diameter ranges in a
factors into consideration, a general assessment fairly straightforward fashion. In addition,
of the tunneling methods with respect to their shield machines have been devised which are
suitability in individual cases can be carried fitted with two or three overlapping cutting
out. wheels staggered one behind the other. In this
The remainder of these recommendations deal way, cross-sections which are not circular can
exclusively with the process technical features be driven. The installations in question are
to be considered when using tunneling special forms of shield machines for special
machines, and essential selection and purposes.
evaluation criteria for the corresponding Apart from these machines being geared to a
geotechnical fields of application. circular form and diameter, the length of the
sections to be driven represents a further
3.2. Explanation of the Construction important feature especially for the economic
Methods application of a tunneling machine.
The “shotcreting construction method” is an The profile accuracy of the cavity cross-section
independent method, whose possibilities or is particularly high when tunnel machines are
rather principles of supporting the cavity used. During heading, care should be taken to
combine with various tunneling methods. ensure that the predetermined driving
Under the term “tunneling with systematically tolerances are adhered to. Unscheduled
advancing support”, we understand tunneling deviations from the axis can,
method which embrace the systematic and thus in contrast to universal headings, by and large
not simply the partial application of suitable only be corrected with considerable difficulty.
supporting means, which are applied for the
advance stabilization of the face area. These
include: the forepoling method, methods with
pipe screens, screens comprising injection
lances, screens with freezing lances, screens
comprising horizontal HPG columns.
Large-area freezing or grouting is methods
designed to improve the subsoil, which then
facilitate the application of a construction
method such as shotcreting. The tunneling
classification then relates to the improved
subsoil conditions.
Whereas the form and size of the cross-section
in the case of the “universal headings” can be
as desired and in fact, can alter within a length
of tunnel, this flexibility does not exist when
tunneling machines are applied.
Generally speaking, tunneling machines in
accordance with their function are circular and
thus possess a given shape. This restricts their
application should the utilization of a circular
cross-section not be purposeful or necessary
and therefore, increases the costs. Tunneling
machines have also been developed which do

II-3
 Bautechnische Merkmale Merkmale des Tunnels/Features of tunnel Umwelt/Environment
eines Tunnels
Querschnitts- Querschnitts- Tunnell nge Sicherung geford. Grund(G)- L rm- Gas- Schutz
Technical features of gr §e from Ausbau Profilge- Schicht(S)- ersch tte- Staub- d.Per-
a tunnel nauigkeit Wasser rungen Entwickl. sonals
Umwelt
Size of cross- From of cross- Length of Lining Required Groundwater(G) Noise Gas Protec-
Environment
section section tunnel profile Underground vibra- dust tion of
accuracy water(U) tions devel- labour
opment force
gleich- ver nder- gleich- ver nder- kurz lang zwei- ein- gro§ ohne mit
bleibend lich bleibend lich schaling schaling high Zusatz- Zusatz-
Tunnel uniform changing uniform changing short long 2-shells 1-shell ma§n. ma§n.
Bauverfahren without with
Tunneling method extra extra
measures measures
Universeller Vortrieb
Universal excavation
Festgestein/Solid rock
Sprengvortrieb
Drill+blast X X X X X X X X 0 SX GX q q s
Teilschnittmasch.Vortrieb
Roadheader X X X X X X X X X SX GX s q s
Spritzbetonbauw./N T
Shotcreting method/NATM X X X X X X X X X SX GX s s s
Messervortrieb
Forepoling X 0 X 0 _ X X X X 0 GX s s q
Vortrieb mit systematisch
voreilender Sicherung X X X X X X X 0 0 0 GX s s q
Heading with systematic
advance support
Lockergestein/soft ground
Maschineller Vortrieb
Mechanical heading
Festgestein/Solid rock
Tunnelbohrmasch.-Vortr. Kreis
TBM driving X 0 circle 0 _ X X X X SX GX s s s
Schildmasch.-Vortrieb Kreis
Shield machine driving X 0 circle 0 _ X X X X X X s s q
Rohrvortrieb Kreis
Pipe jacking X 0 circle 0 X X _ X X X X s s q
Vorpre§verfahren X 0 X 0 X X 0 X X X X s s q
Jacking method
Lockergestein/soft ground
Microtunnelvortrieb Kreis
Micro-tunnelling X 0 circle 0 X 0 0 X X X _ s s q
Eignung der Bauverfahren: X gut geeignet 0 nicht geeignet - nicht blich Auswirkungen: q gro§ s geringer
Suitability of the construction method:X well suited 0 not suited - not usual Effects: q high s slight
1 Bauverfahren f r Tunnel in geschlossener Bauweise
Construction methods for mined tunnels

II-4
4. Tunneling machines TM particularly in friable rock, it must be ensured
that the placing of support arches, lagging
Tunneling machines (TM) either head the plates and anchors, in certain cases, even
entire tunnel cross-section with a cutter head or shotcrete, is possible directly behind the cutter
cutting wheel full-face or in part segments by head. It should be possible to carry out
means of suitable extraction equipment. preliminary investigations a n d rock
During the excavation phase, the machine is strengthening from the machine.
moved forward either continuously or stroke- In the case of bore diameters of > 10 m, so-
by-stroke. called expansion machines can also be applied.
A difference is drawn between tunnel boring Starting from a continuous pilot tunnel, the
machines TBM and shield machines SM. profile is expanded in one or two working
Tunnel boring machines remove the rock at the phases using correspondingly designed cutter
face, with the support generally being installed heads.
afterwards, following up at a distance. During excavation at the face, small pieces of
The machines are held in place during the rock, accompanied by an amount of dust, are
excavation phase by means of grippers pressed produced. As a consequence, devices for
laterally against the tunnel walls. restricting the dust development and dedusting
Shield machines generally support the subsoil are necessary for these machines:
that is being penetrated and the face by direct _ wetting with water at the cutter head
means during the excavation phase. The shield _ dust shield behind the cutter head
is advanced during excavation by jacking _ dust removal with dedusting on the back-up
against the completed lining. The material transfer and supplies for the
A systematic compilation of tunneling ma- machine call for what, in some cases, can be
chines is provided in Fig. 2, which was based very long back-up facilities.
on the classification contained in this section.
4.1.2. Tunnel boring machines with shields
4.1. Tunnel Boring Machines (TBM) TBM-S
A distinction is drawn between tunnel boring In solid rock with low stability or friable rock,
machines without shield body and those with tunnel boring machines are equipped with a
one(Fig.3). closed shield body. In this case, it is advisable
to carry out supporting within the protection of
4.1.1. Tunnel boring machines without the shield tail skin (segments, pipes, etc.),
shields against which the machine supports itself. The
Tunnel boring machines are employed in solid gripper system is then no longer needed.
rock with medium to high face stability. They Otherwise, the explanations already provided
do not possess a completely closed shield for tunnel boring machines also apply here.
body. Economic application can be strongly
influenced and restricted through high wear 4.2. Shield Machines SM
costs of the cutting tools. A distinction is drawn between Shield Ma-
Generally speaking, only a circular cross- chines with full-face extraction (cutter head)
section can be broken out by these machines. SM-V and shield machines with part extraction
A rotating cutter head, which is equipped with (milling boom, excavator)SM-T.
roller bits (discs), possibly with tungsten Shield machines are employed in loose soils
carbide bits, is pressed against the face and with or without groundwater, in the case of
removes the rock through its notch effect. In which generally the subsoil surrounding the
order to provide the contact pressure at the cavity and the face have to be supported. The
cutter head, the machine is held radially by characteristic feature of these machines is the
means of hydraulically moveable grippers. type of face support (Fig. 3).
Extraction is gentle on the rock and results in
an accurate profile. 4.2.1. Shield Machines with full-face
The machine occupies a large part of the cross- excavation SM-V
section. Systematic supporting is normally 4.2.1.1 SM-V1 Face without support
carried out behind the machine (10 to 15 m and If the face is stable, e.g. in clayey soils, so-
more behind the face). In less stable and called open shields can be employed. The

II-5
cutter head equipped with tools removes the by a bulkhead. The pressure needed for
soil; the loosened soil is carried away by supporting the face can be regulated with great
means of conveyor belts or scraper chains. precision either by means of an air cushion or
by controlling the speed of the delivery and
4.2.1.2 SM-V2 Face with mechanical support feed pumps. Supporting pressure calculations
Supporting of the face is carried out via an are required.
almost closed cutter head. The plates arranged The soil is removed full-face by means of a
between the spokes are elastically supported; cutter head equipped with tools. Hydraulic
they are pressed up against the face. Extraction conveyance with subsequent separation is
is executed full-face via the cutter head essential.
equipped with tools; the loosened soil passes If it is necessary to enter the working chamber
through slits, whose opening width is variable, (tool change, repair work, removing obstacles),
between the spokes and the supporting plates, the fluid must be replaced by compressed air.
into the working chamber. The supporting fluid (bentonite, polymer) then
The material is removed via conveyor belts, forms a slightly air-permeable membrane at the
scraper chains or by hydraulic means. face, whose life span is restricted. This
Scraper disc shields possess a high degree of membrane facilitates the supporting of the face
mechanization. Through the constant full-face through compressed air and should be renewed
contact of the cutting wheel with the face, high if need be.
torque is required. When the machine is at a standstill,
In the case of types of soil, which tend to flow, mechanical supporting of the face is possible
supporting in the vicinity of the slits is by means of segments, which can be shut, in
incomplete, which can lead to settlements. It is the cutting wheel or through plates that can be
extremely difficult to remove obstacles. extended from the rear. These solutions are
advisable on account of the limited duration of
4.2.1.3 SM-V3 Face with compressed air the membrane.
application Stones or banks of rock can be reduced to a
If groundwater is present, it has to be held back size convenient for conveyance through discs
in the case of machines belonging to types on the cutting wheel and/or stone crushers in
SM-V1 and SM-V2 unless it can be lowered. the working chamber.
Either the whole tunnel is subjected to
compressed air or the machine is provided with 4.2.1.5 SM-V5 Earth pressure balance face
a bulkhead so that only the working chamber is The face is supported by earth slurry, which is
under pressure. Airlocks are essential in both formed from the material that has been
cases. removed. The shield's working chamber is
Particular attention must be paid to the closed to the tunnel by means of a bulkhead.
compressed air leakage via the shield tail seal More or less closed cutting wheels equipped
and the lining. with tools extract the soil. An extraction screw
The support which is realized by the under pressure carries the soil out of the
application of compressed air acts directly. working area.
Through suitable measures, it is also possible The pressure is checked by loadcells, which
to avoid an accumulation of compressed air, are distributed over the front side of the
e.g. when sand lenses with water under bulkhead. Mixing vanes on the rear of the
pressure occur. cutting wheel and the bulkhead are intended to
ensure that the soil obtains a suitable
4.2.1.4 SM-V4 with fluid support consistency.
In the case of these machines, the face is The supporting pressure is controlled through
supported by a fluid that is under pressure. the thrust of the rams and the speed of the
Depending on the permeability of the subsoil conveyor screw. The soil material in the screw
that is present, effective fluids must be used for or additional mechanical installations must
supporting, whose density and/or viscosity can ensure a seal in the extraction equipment, as
be varied. Bentonite suspension has proved to otherwise the supporting pressure in the
be particularly effective. working chamber cannot be retained due to the
The working chamber is closed to the tunnel uncontrolled escape of water or soil.

II-6
Complete supporting of the face, especially in
the upper zone, only then succeeds providing
the supporting medium soil- can be
transformed into a soft to stiff-plastic mass. In
this connection, the percentile share of the fine
grain smaller than 0.6 mm has a considerable
influence.
In order to extend the range of application of
shield machines with earth pressure balance
support, suitable agents for conditioning the
soil material can be applied: bentonite,
polymer, foam from polymers. In such cases,
the environmental compatibility of the material
for landfill purposes must be taken into
consideration.

4.2.2. Shield machines with partial axe

excavation SM-T
4.2.2.1 SM-T1 Face without support
If the face is perpendicular or stable with a
steep slope, it is possible to use this type of
shield. The machine merely comprises the
shield body and the extraction tool (excavator,
milling boom or scarifier). The soil is removed
via conveyor belts or scraper conveyors.

4.2.2.2 SM-T2 Face with partial support

The face can be supported by platforms and/or
breasting plates.
In the case of platform shields, the front
section is divided up by one or a number of
platforms on which slope form, which support
the face. The soil is removed manually or by
mechanical means.
Platform shields possess a low degree of
mechanization. Disadvantageous is the danger
of major settlements resulting from un-
controlled face support.

II-7
 TBM ohne schild TBM
TBM
TBM without Shield
Tunnelbohrmaschinen
TBM
Tunnel Boring Machines
TBM mit Schild
TBM-S TBM-S
TBM with Shield

Ortsbrust ohne Stützung SM-V1

Face without support

Ortsbrusut mit
Tunnelvortriebs- mechanischer Stützung SM-V2
maschinen Face with mechanical
TVM support
Tunnelling
Machines Schildmaschinen Ortsbrust mit Druckluft-
mit Vollschnittabbau Beaufschlagung SM-V3
SM-V Face with compressed
Shield Machines with air application
full-face
Ortsbrust mit Flüssig-
Keitsstützung SM-V4
Face with fluid support

Ortsbrust mit Erddruck-

Schildmaschinen Stützung SM-V5
SM Face with earth pressure
Shielded Machines balance support

Ortsbrust ohne Stützung SM-T1

Face without support

Ortsbrust mit Teilstützung SM-T2

Schildmaschinen mit Face with purtial support
teiltlächigem Abbau
SM-T Ortsbrust mit Druckluft-
Shield Machines with Beaufschlagung SM-T3
part heading Face with compressed
air application

Ortsbrust mit Flüssigkeits-

Stützung SM-T4
Face 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-8
In the case of shield machines with breasting shield SM-V5
plates, the face is supported through breasting _ earth pressure balance shield SM-V5 _ shield
plates, which are mounted on hydraulic without support SM-V1
cylinders. The breasting plates are partially _ fluid shield SM-V4_ TBM-S
retracted for removing the soil manually or by
mechanical means.
A combination of breasting plates and 4.4. Special forms
platforms is possible. If supporting of the roof 4.4.1. Finger shields
area is sufficient, extensible breasting plates The shield body is split up into fingers, which
can be used there. can be extended individually. The soil is
removed via roadheaders, cutting wheels or
4.2.2.3 SM-T3 Face with compressed air excavators. An advantage of finger shields is
application that they deviate from the circular form and
If groundwater is present, this must be held in e.g. can also excavate horse-shoe profiles. In
check in the case of machines of the type SM- the latter case, the base is usually open. The
T1 and SM-T2. The tunnel is then set under forepoling is also used.
compressed air or the machines are provided
with a bulkhead. The material is removed 4.4.2. Shields with multi-circular cross-
hydraulically or dry via a material lock. sections
These shield types represent the latest state of
4.2.2.4 SM-T4 Face with fluid support development for fully mechanized headings. In
In the case of this shield type, the working the case of these machines, the staggered
chamber is also closed by a bulkhead. It is cutting wheels are designed to overlap.
filled with a fluid, whose pressure is regulated
via the speed of the delivery and feed pumps. 4.4.3. Articulated shields
The soil is removed via a cutter, which, in Practically all-existing shields can be provided
similar fashion to suction dredgers, also takes with an articulating joint. If the ratio of the
away the fluid-soil mixture. shield body length to the shield diameter
exceeds the value l, generally a joint is
incorporated in order to improve the steability.
4.3. Adaptable dual purpose shield The arrangement can also be necessary if
machines extremely tight curve radii are to be driven.
A large number of tunnels pass through
strongly varying subsoil conditions, which can 4.4.4. Cowl shield
range from rock to loosely bedded soil. As a The shield cutting edge is tapered to
result, tunneling methods have to be geared to approximate the natural angle of slope of the
the geotechnical prerequisites and shield soil. When tunneling under compressed air,
machines, which a r e correspondingly this means that safety against blowout is
adaptable, employed. enhanced.
a) Shield machines, in the case of which the
extraction method can be changed without 4.4.5. Displacement shield
modification: Only suitable for soft-plastic soils. The
_ earth pressure balance shield SM-V5 _ machine has no extraction tool. It is pressed
compressed air shield SM-V3 into the soil, which results in this being
_ fluid shield SM-V4 _ compressed air shield partially displaced and partially removed
SM-V3 through an aperture in the bulkhead.
b) Shield machines, in the case of which the
extraction method can be changed through 4.4.6. Telescopic Shields
modification. Findings are available with the In order to arrive at higher rates of advance,
following combinations: telescopic shields have been designed.
_ fluid shield SM-V4 _ shield without support Essentially, the objective is to install the lining
SM-V1 during the removal of the soil.
_ fluid shield SM-V4 _ earth pressure balance

II-9
4.5. Supporting and lining unstable, squeezing rock. Rolled steel sections
As far as the process techniques referred to in or lattice girders are used as support arches.
these recommendations are concerned, the Support arches are normally installed directly
tunneling machine together with the support behind the cutter head in sections in the roof
and/or lining represent a single unit in terms of zone or as a closed ring.
process technology.
4.5.2. Tunnel boring machines with shield
4.5.1. Tunnel boring machines TBM TBM-S and shield machines SM
Due to the excavation procedure which is In the case of tunnel boring machines with
gentle on the rock and the advantageous shield or shield machines, the support is
circular form, the extent of the necessary installed within the protection of the shield tail.
supporting measures is usually less than for This usually consists of prefabricated
example for drill + blast. In less stable rock, segments.
the exposed areas have to be supported quickly Apart from supporting the surrounding subsoil,
in order to restrict any disaggregation of the it serves in the case of most machines of this
rock and thus retain the rock quality as far as type as the abutment for the thrust rams.
possible. The load transfer between the lining and the
Should breaks occur in the vicinity of the subsoil is created by grouting the annular void
cutter head, the extent of the necessary at the shield tail as continuously as possible.
supporting measures can increase considerably. This does not apply to lining systems, which
are directly pressed against the subsoil.
4.5.1.1 Rock bolts In general, it must be ascertained whether a
Rock bolts are generally arranged radially in lining comprising an inner shell made of
the cross-sectional profile of the tunnel, a rock reinforced or un-reinforced concrete is needed.
matrix-oriented set-up enhance the effect of the Segments and pipes are normally utilised as
shear dowels. Installed locally, they prevent the single skin linings.
flaking or detaching of rock plates, arranged
systematically, they prevent loosening of the 4.5.2.1 Concrete and reinforced concrete
exposed tunnel sidewall. Rock bolts are segments
especially suitable for subsequently increasing The customary precast elements are concrete
the lining strength, as they can still be installed or reinforced concrete segments. Alone the
at a later stage. stresses caused by transport and installation
The anchors are installed in the vicinity of the makes it necessary for the segments to be
working platform behind the machine or in reinforced. Segments with steel fibber
special cases, directly behind the cutter head. reinforcement have also been designed in order
to strengthen the edges and corners, which
4.5.1.2 Shotcrete cannot be reinforced by rods, through steel
Shotcrete serves to seal the exposed rock fibbers.
surface either partially or completely (thick-
ness 3 to 5 cm) or provide it with a supporting 4.5.2.2 Cast steel and steel segments
layer (thickness 10 to 25 cm, in exceptional Through the development of casting
cases, even more). In order to enhance the technology, segments today can be supplied
loadbearing capacity of the shotcrete lining, it made of cast steel, e.g. with the material
is provided with a single-layer (on The rock designation GGG 50, with low overall
side) or two-layers (rock and exposed side) of thickness, sufficient dimensional accuracy and
mesh reinforcement. Alternatively, steel fibber sufficient elasticity.
shotcrete can be applied. The shotcrete is In exceptional cases, as e.g. extremely narrow
generally installed in the vicinity of the curves and in the vicinity of apertures in the
working platform behind the machine. lining, welded steel segments can represent a
4.5.1.3 Support arches technical solution for overcoming load con-
Support arches serve to effectively support the contortions on the lining.
rock directly after the excavation and to protect
the working area. As a consequence, they are,
first and foremost, applied in friable and 4.5.2.3 Liner plates

II-10
Pre-formed steel plates in the form of liner and tunneling machines
plates can represent an economic solution as a
full surface provisional support in extremely 5.1. Ranges of application for tunneling
friable rock. machines
The individual tunneling machines are suitable
4.5.2.4 Extruded concrete for certain geotechnical and hydro-
Extruded concrete is a tunnel lining, which is geographical ranges of application in con-
installed, in a continuous working junction with their process-related and
process as an unreinforced or steel-fibre technical features.
reinforced concrete support behind the The specific types of machines are related to
tunneling machine between the shield tail and their main ranges of application in Fig.4 with
a mobile inner form. Thus, the extruded geo-technical terms and parameters as the
concrete in its fresh state already supports the basis. In addition, it is shown there just how far
surrounding rock, also in groundwater. An an extension of the range of application is
elastically supported stop-end formwork, possible should this present itself as a result of
which is pushed forwards concrete pressure, simplified methods, in order to increase the
assures a constant support pressure in the economy or with regard to the heterogeneity of
liquid concrete. the subsoil that is present.
As one of the most essential influencing
4.5.2.5 Timber lagging factors for the application is the lack or
In non-water bearing soil, the primary support presence of groundwater, the fields of
can comprise a wooden or reinforced concrete application are divided into subsoil with or
slatted construction, which is installed between without groundwater.
steel profiles (ribs and lagging), which is Extremely varied extraction tools can be used
assembled protected by the shield tail. When for removing the subsoil that is present. They
the shield tail releases the steel ribs, they and, are listed in accordance with their suitability
in turn, the lagging, are pressed against the soil for the geotechnical ranges of application and
using hydraulic jacks. The tunneling machine the machine types.
can be advanced by thrusting against this pre- The forms of supporting and lining suit able
stressed construction. for the individual machines are presented
under 4.5. As a result, they have not been listed
4.5.2.6 Pipes separately in a table.
Pipe-jacking represents a special method, in
the case of which reinforced concrete or steel
pipes are thrust forward from a jacking station
to serve as a support and/or final lining.
For certain construction projects, rectangular
cross-sections are also employed with the
jacking method.

4.5.2.7 Reinforced Concrete

Reinforced concrete is only used n conjunction
with blade shields. In the same way as
shotcrete, reinforced shotcrete can be applied
in conjunction with tunneling machines for
supporting purposes when they do not transfer
the thrusting forces onto the lining. The
reinforced concrete is produced in 2.50 to 4.50
m wide sections protected by so-called trailing
blades, which are supported on the last
concreted section by conventional means with
mobile formwork.

5 . Relationship between geotechnics

II-11
 application (abrasiveness according to Cerchar,
Schimanek, et al). A restriction of the gripper
force of the TBM can also place its application
in question.
To assess the rock, the cleavage strength _z
≈ 25 to 5 [MN/m2] and the RQD value are
required. Given a degree of decomposition of
the rock with RQD of 100 to 50 [%] and a
fissure spacing of > 0.6 m the application of a
TBM appears assured.
Should the decomposition be higher, the
stability has to be checked.

TBM-S
The main field of application is in friable to
unstable rock, also with inbursts of
underground and fissure water. The bonding
strength is greatly reduced given possibly the
same rock strength in stable rock. This
corresponds to a fissure gap of ≈ 0.6 to 0.06
[m] and a RQD value between approx. 50 and
10 [%]. Generally, however, an application of
the TBM-S is possible given lower rock
compressive strength _D between approx. 50
and 5[MN/m2] and correspondingly less
cleavage strength of _ z between approx. 5 and
0.5 [MN/m2].

SM-V1
This type of machine is mainly used in over-
consolidated and thus dry, stable clay soils. In
order to make sure that no harmful surface
settlements occur even given thin overburdens,
the compressive strengths _D of the material
should not be less than approx. 1.0 [MN/m2].
The cohesion cu accordingly registers values
above approx. 30 [kN/m2].
Only in rock which is relatively immune to
overbreak can underground and fissure water
ingress be coped with.
3. Systeme der Tunnelvortriebsmaschinen
Tunneling machine systems SM-V2
On account of the full-face supporting cutter
5.2. Important selection and evaluation head, easily removed, largely dry types of soil
criteria can be mastered, first and foremost non-stable
cohesive soils or interstratifications comprising
TBM cohesive and non-cohesive soils. Major
The main range of application is in stable to intercalation such as boulders is extremely
friable rock, in the case of which underground difficult to cope with.
and fissure water inbursts can be mastered. The The cohesion cu of these soils amounts to
uni-axial compressive strength should amount between 30 and 5 [kN/m2]. The grain size is
roughly to between 300 and 50 [MN/m2]. restricted upwards due to the slit width in the
Higher strengths, toughness of the rock and a cutter head. In order to ensure that surface
high proportion of abrasion resistant minerals settlements are kept to a minimum, the slit
represent economic limits for -

II-12
width and contact pressure have to be supporting purposes in the roof and platform
optimized. zone. Slightly to non-cohesive clay-sand soils
with a corresponding angle of friction are the
SM-V3 main range of application.
This machine under compressed air working is
mainly used when types SM-V1 and SM-V2 SM-T3
have to operate in groundwater. Its main The application of this type of machine is
application must be regarded as in soils with given when types SM-T1 and SM-T2 are to be
interstratification. The air permeability of the used in groundwater. Either the entire working
rock and the air consumption and the related area, including the excavated tunnel or solely
blow -out danger are the governing criteria for the working chamber is subjected to
the application of this type of machine. compressed air.

SM-V4 SM-T4
Its main range of application is tunneling in When clay-sand mixtures are to be removed
non-cohesive types of soil with or without under water, this type of machine is used. The
groundwater. requirements concerning t h e ground
During the excavation process, a fluid under correspond to type SM-T4. Obstacles can be
pressure e.g. bentonite suspension supports the cleared using the cutting boom. Supporting
face. Layers of gravel and sand are the typical plates are arranged in the roof zone.
subsoil. Coarse gravel can in certain cases
prevent membrane formation. In the event of
high permeability, the supporting fluid must be
adapted to suit. Major stratification, which
cannot be pumped, is reduced in advance
crushers. The proportions of ultra-fine grain <
0.02 mm should amount to ≈ 10%. Higher
quantities of ultra-fine material can lead to
difficulties during separation.

SM-V5
Types of machines with earth pressure balance
supporting are especially suitable for with
cohesive fractions. In this case, the proportion
of ultra-fine grains < 0.06 mm should amount
to at least 30 %. In order to produce the desired
earth slurry, groundwater has to be present or
water must be added. The necessary
consistency of the spoil can be improved
through the addition of suitable conditioning
agents such as bentonite or polymer. In this
way too, the danger of sticking is considerably
reduced.

SM-T1
This type of machine can be used providing the
face is thoroughly stable. Refer also to SM-T1.

SM-T2
This type of machine can be used when the
support due to the material lying on the
platforms at a natural sloping angle suffices for
a conditional control of deformations during
tunnel advance. Breastplates can be used for

II-13
 Baugrund Fels/Festgestein/
Hard rock/soil Boden/Lockergestein/
Soft rock/soil
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 σ D[MN/ ‡u] 300 bis 50 50 bis 5 1,0 0,1
Rock Compressive strength
Zugfestigkeit σ z[MNl‡u] 25 bis 5 5 bis 0,5
Tensile strength
RQD-Wert RQD[%]
100 bis 50 50 bis 10
RQD value
Kluftabstand [m]
>2,0 bis 0,6 0,6 bis 0,06
Fissure spacing
Koh sion Cu[kNl‡ u]
≥ 30 30 bis 5 30 bis 5
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 supportm.W.
SM-V2 mechan.St zung o.W.
SM-V2 mech.support m.W.
SM-V3 mit Druckluft o.W.
SM-V3 with compressedm.W.
air
SM-V4 Fl ssigkeitsst o.W.
tzung
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.
air
SM-T3 with compressedm.W.
SM-T4 Fl ssigkeitsst o.W.
tzung
SM-T4 fluid support m.W.
Abbauwerkzeug V rollend rollend sch lend sch lend l send/sch lend l send
Extracion tool (Diskenmei§el) (Diskenmei§el) (Flachmei§el) (Flachmei§el) (Stichel/Flachmei§el)(Stichel)
rolling rolling stripping stripping loosening/stripping loosening
(cutter disc) (disc bit) (flat bit) (chisel) (cutter/flat bit) (pick)
T ritzend ritzend ritzend sch lend sch lend l send
(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
II-14
5.3. Pointers for special geotechnical and subterranean station, employ i n g soil
constructional conditions improvements should these be called for.
Due to special marginal conditions, the The greater the proportion of ultra fine
application of a certain method and/or a material in the subsoil, the more attention has
tunneling machine can be considerably to be paid to spoil separation in the case of
restricted. By use of suitable measures, fluid supported shield machines.
however, an application can be made possible, The requirements on the water content and/or
above all, providing these special conditions the degree of purity of the separated soil
only occur locally or over a limited zone. The material then govern the limits of the economy
decisive factor is then the economic feasibility. of the method.
Through lowering the groundwater, a The operational safety of a method is, among
simplified technique for the tunneling other things, dependent on a tunnel’s over-
machines can be applied, which e.g. facilitates burden. This should generally correspond at
the removal of obstacles, should these be least to the diameter of the tunnel excavated, if
expected at very frequent intervals. additional measures are to be avoided. This
In the case of strongly fluctuating geotechnical must be accorded special attention in the case
conditions, the possibility of being in a of large diameters.
position to adapt the operating mode of the The unrestricted application of certain types of
tunneling machine brings advantages. This is, machine is not always assured as the diameter
above all, purposeful when lengthy inter- increases and is only possible in conjunction
connected sections are concerned (see 4.3). with suitable measures. In the case of tunnel
When selecting the suitable tunneling ma- boring machines with large diameters,
chines, a critical evaluation of eventual machines with shield body and systematic
additional equipment is advisable, which may placing of segments have proved themselves.
be required to cope with any deviations from As far as earth pressure balance shield
the projected geotechnical conditions within a machines are concerned, extremely high
certain range. torques at the cutter head are necessary, which
By means of grouting, freezing, vibrator possibly cannot be attained in the case of very
compaction or soil replacement, the subsoil large diameters.
can be improved. This is suitable for the entire As far as earth pressure balance shield
tunnel cross-section but most importantly for machines are concerned, cutter discs can be
the area above the tunnel when only thin employed for reducing coarse gravel and
overburden is present. boulders. The dimensions of the screw
Using compressed air when a thin overburden conveyor must be designed in such a fashion
is present, e.g. below a watercourse, ballast or the coarse lumps which are present after
a waterproofing and ballasting layer should be extraction can be removed. A screw without a
installed. shaft is suitable for conveying coarse lumps.
When fluid support is used, additional Certain clays or rocks containing clay can
measures are required in order to avoid cause the cutter head to stick and to form
uncontrollable suspension losses given high bridges over apertures for removing material.
permeability of the soil and thin overburden. This phenomenon can be counteracted through
Should there be a high frequency of coarse the proper shape, flushing installations or
gravels and boulders in the sand, the utilization additives, which reduce the stickiness.
of a rock crusher enhances the operational Ingresses of gas require flameproof protection
safety in the case of fluid supported shield for the tunneling machines or a change of
machines in addition to equipping the cutter operational mode.
head with cutter discs.
A tunneling machine is only in the position to
head a circular cross-section, which has a
constant diameter. However, it is technically
possible to expand the driven circular cross-
section over short stretches subsequently in
such a way that other, above all larger cross-
sectional forms are created, e.g. for a

II-15
 Italy

ITA WORKING GROUP No. 14

(ITA WG14)

“MÉCANISATION DE L’EXCAVATION”
“MECHANIZATION OF EXCAVATION”

Tuteur/Tutor Animateur Vice-Animateur

S.KUWAHARA N.MITSUTA M.DIETZ

PRÉPARATION DU RAPPORT “RECOMMANDATIONS

POUR LE CHOIX DES MACHINES FOREUSES”

PREPARATION OF THE REPORT “GUIDELINES FOR THE

SELECTION OF TBM’S”

(Contribution from the Italian Tunneling Association

“Mechanized Tunneling”working group - GL14, to the ITA
WG14)

World Tunnel Congress‘98

Tunnel and Metropolis
24th ITA Annual Meeting
25 - 30 April 1998
Sao Paulo - Brazil
 CONTENTS
1. Aim and Scope (deleted)........................................................................................................................1
2. Classification and Outline of Tunnel Excavation Machines .............................................................1
2.1. Classification of tunnel excavation machines.............................................................................1
2.2. Rock tunneling machines ..............................................................................................................3
2.2.1. Unshielded TBMs..................................................................................................................3
2.2.2. Special Unshielded TBMs....................................................................................................3
2.2.3. Single Shielded TBMs: SS-TBMs ......................................................................................3
2.2.4. Double Shielded TBMs: DS-TBMs....................................................................................4
2.3. Soft Ground Tunneling Machines ................................................................................................4
2.3.1. Open Shields ..........................................................................................................................4
2.3.2. Mechanically Supported Closed Shields............................................................................4
2.3.3. Mechanical Supported Open Shields..................................................................................5
2.3.4. Compressed Air Closed Shields..........................................................................................5
2.3.5. Compressed Air Open Shields.............................................................................................5
2.3.6. Slurry shields..........................................................................................................................5
2.3.7. Open slurry shields................................................................................................................6
2.3.8. Earth Pressure Balance Shields – EPBS ............................................................................6
2.3.9. Combined Shields: Mixshield, Polyshield.........................................................................7
3. Conditions for Tunnel Construction and Selection of TBM Tunneling Method ...........................7
3.1. Investigations ..................................................................................................................................7
3.1.1. Introduction ............................................................................................................................7
3.1.2. Parameter selection..............................................................................................................12
3.1.3. Monitoring during construction.........................................................................................24
3.1.4. TBM tunneling monitoring system...................................................................................24
4. REFERENCES......................................................................................................................................28

III-ii
1. Aim and Scope (deleted)

2. Classification and Outline of

Tunnel Excavation Machines
2.1. Classification of tunnel excavation
machines

All over the world there are different

classification schemes for tunnel excavation
machines (TMs), based o n different
classification purposes.

T h e p r o p o s e d classification scheme
represented in fig. l is based on the possibility
of dividing TMs on the basis of_

_ ground support system

_ excavation (method and tools)
_ reaction force tool

Following the two machine categories into

which all TMs may be grouped, the next
paragraphs broadly illustrate all types of TMs.

III-1
2.1 - General class f cat on scheme for tunnel ng mach ne
- General classification scheme for tunneling machine
1 - General classification scheme for tunneling machine Excavation Excavation
Excavation Excavation
ion Excavation Excavation Excavation Excavation
Excavation Excavation

Excavation Excavation Excavation Excavation

Excavation

Excavation Excavation Excavation

Excavation
Excavation Excavation Excavation Excavation

Excavation Excavation Excavation Excavation

Excavation Excavation Excavation Excavation

Excavation Excavation Excavation

Excavation

Excavation Excavation Excavation

Excavation Excavation Excavation

Excavation

Excavation
Excavation Excavation Excavation
Excavation

Excavation Excavation Excavation

Excavation

Excavation
Excavation

Excavation Excavation Excavation

Earth Pressure Balance Shield-EPBS

Excavation
Special EPBS
Excavation Excavation
Earth Pressure Balance
Earth Pressure Balance Shield-EPBS
Shield-EPBS
Special EPBS

Earth
EPBS
Special

Shield-
Special EPBS

Balance
Pressure
III-2
2.2. Rock tunneling machines basically consists of:
_the traveling element which basically consists
2.2.1. Unshielded TBMs of the reaming head, on which the cutting
tools are fitted_and the primary mucking
system_
_a stationary element located inside the pilot
tunnel opposite the reaming head, which
counters the thrust jacks on the cutting head
using two pairs of grippers;
Function principle – A cutterhead, rotating on _a rear portion containing the engines_the
an axis which coincides with the axis of the driving gear and back-up elements.
tunnel being excavated, is pressed against the A special type of RBM is the Down Reaming
excavation face; the cutters (normally disc Boring Machine_this machine is used for shaft
cutters) penetrate into the rock, pulverizing it excavation and enables the top-to-bottom
locally and creating intense tensile and shear reaming of a pilot tunnel dug using a Raise
stresses. As the resistance under each disc Borer_see below_.
cutter is overcome, cracks are created which Main field of application - Rock masses whose
intersect creating chips. Special buckets in the characteristics range from optimal to moderate
cutterhead allow the debris to be collected and with medium to high self-supporting time.
removed to the primary mucking system. The
working cycle is discontinuous and includes:
1) excavation for a length equivalent to the 2.2.2.2 Raise Borer
effective stroke; 2) regripping; 3) new - Function principle - The Raise Borer is a
excavation. machine used for shaft excavation which
Main components of the machine - The TBM enables the top-to-bottom reaming of a small
basically consists of: diameter pilot tunnel created using a drilling
_the traveling element which basically consists rig.
of the rotating cutting head and the primary A cutterhead, rotating on an axis, which
mucking system_ coincides, with the axis of the tunnel being
_a stationary element which counters the thrust excavated, is pulled against the excavation face
jacks of the cutterhead using one or more by a drilling rod guided through the pilot
pairs of grippers which anchor the TBM tunnel. The cutters provoke crack formation
against the tunnel walls_ using the same mechanism illustrated for the
_a rear portion containing the driving gear and unshielded TBMs. Debris falls to the bottom of
back-up elements; the shaft where it is collected and removed.
Depending on the type of stationary element it Main components of the machine - The Raise
is possible to divide unshielded TBMs into: Borer basically consists of 3 parts:
main beam types or kelly types. _ the cutterhead (discs or pin discs);
Main field of application - Rock masses whose _ the drilling rod which provides torque and
characteristic range from optimal to moderate pull to the cutterhead;
with medium to high self-supporting time. _ a body, housed outside the shaft, which gives
the drilling rod the necessary torque and pull
for excavation.
2.2.2. Special Unshielded TBMs
Main field of an application - Rock masses
2.2.2.1 Reaming Boring Machines - RBMs
with optimal to poor characteristics.
Function principle - The Boring Machine is a
TM which allows a tunnel made using a TBM
(pilot tunnel) to be widened (reaming). 2.2.3. Single Shielded TBMs: SS-TBMs
The function principle on which it is based is Function principle -
identical to that for the unshielded TBM; the See the section for
working stages are also the same as for the unshielded TBMs. In
unshielded TBM. this case the working
Main components of the machine - The RBM cycle is also -

III-3
discontinuous and includes: 2.3.1. Open
l) excavation for a length equivalent to the
Shields
effective stroke; 2) regripping (using the
Function principle -
longitudinal thrust jacks braced against the
The open shield is a
precast segments of the tunnel lining) and
TM in which face
simultaneous laying of tunnel lining using
excavation is -
precast segments; 3) new excavation.
accomplished using a partial section
Main components of the machine
cutterhead.
_the cutterhead (discs), which can be
At the base of the excavating head are hand
connected rigidly to the shield or articulated;
shields and partly mechanized shields in which
_ the protective shield which is cylindrical or
excavation is accomplished using a roadheader
slightly truncated cone-shaped and contains
or using a bucket attached to the shield, and
the main components of the machine; the
using an automatic unloading and mucking
shield may be monolithic (the machine is
system.
guided by the thrust system and/-
or cutterhead) or articulated (the machine is
Main components of the machine
guided by the thrust
_ the face excavation system;
system and/or shield articulation);
_ the protective shield whose shape can be
_ the thrust system which consists of a series
altered to suit the type of section to be
of longitudinal/hydraulic jacks placed inside
excavated (non-obligatory circular section);
the shield which are braced against the
_ the thrust system consisting of longitudinal
tunnel lining.
jacks.
Main field of application - Rock masses whose
Main field of application - Rock masses whose
characteristics vary from moderate to poor.
characteristics vary from poor to very bad, -
cohesive or self-supporting ground in general.
2.2.4. Double Shielded TBMs: DS- It can also be used in ground, which lacks self-
TBMs supporting capacity using appropriate
preconsolidation or presupport of the -
Function principle - excavation face.
Similar to unshielded
TBMs, but offers the 2.3.2. Mechanically Supported Closed
possibility of a -
Shields
continuous work cycle
owing to the double thrust system, making it
Function principle -
more versatile since it can move forward even
This mechanically
without laying the tunnel lining of precast -
supported, closed
segments.
shield is a TBM in
Main components of the machine:
which the cutterhead
_ the cutterhead (discs);
plays the dual role of
_ the protective shield which is cylindrical or
acting as the cutterhead and supporting the
slightly truncated cone-shaped and -
face using mobile plates, integral to the
articulated, and contains the main machine
cutterhead, thrust against the face by special
component;
hydraulic jacks. The debris is extracted
_ the double thrust system which consists of:
through adjustable openings or buckets and
1) a series of longitudinal jacks;
conveyed to the primary mucking system.
2) a series of grippers, positioned inside the
Main components of the machine
front part of the shield which use the
_ the cutterhead (blades and teeth);
tunnel walls to brace against the thrust
_ the protective cylindrical shield containing
jacks.
all the main components of the machine;
Main field of application - Rock masses whose
_ longitudinal thrust jacks.
characteristics range from excellent to poor.
Main field of application - Soft rocks, cohesive
or partially cohesive ground, self-supporting
2.3. Soft Ground Tunneling Machines
ground in general. Absence of groundwater.

III-4
2.3.3. Mechanical Supported Open 2.3.5. Compressed Air Open Shields
Shields
Function principle - As
Function principle - in the case of open
Similar to that - shields, face -
described for open - excavation is achieved
Shields; face stability is using a roadheader;
achieved using metal face support is -
plates which thrust alternatively against the provided by compressed air in sufficient
face. quantities to balance the hydrostatic pressure
Main components of the machine - Similar to of the ground.
those described for open shields; the metal face Main components of the machine
support plates are located in the upper part of _face excavation system ( roadheader,
the section and are integral to the shield. excavator);
Main field of an application - Soft rocks, _ protective shield shaped to fit the type of
cohesive or partially cohesive ground, self- section to be excavated; the front part, which
supporting ground in general. Absence of houses the roadheader, is closed by a
groundwater. bulkhead separating the shield and -
excavation chamber (pressurized);
_ longitudinal thrust jacks.
Main field of application - The same as for
2.3.4. Compressed Air Closed Shields
compressed air closed shields.
Function principal - In
compressed air closed 2.3.6. Slurry shields
shields the rotating -
cutterhead acts as the 2.3.6.1.Slurry shields-SS
means of excavation
whereas face support is ensured by compressed Function principle - The cutterhead acts as the
air at a sufficient level to balance the - means of -
hydrostatic pressure of the ground. Debris is excavation whereas
extracted from the pressurized excavation face support is -
chamber using a ball valve-type rotary hopper provided by slurry
and then conveyed to the primary mucking counterpressure,
system. namely a suspension of bentonite or a clay and
water mix (slurry).
Main components of the machine This suspension is pumped into the excavation
_ the cutterhead (blades and teeth); chamber where it reaches the face and
_ the protective cylindrical shield containing penetrates into the ground forming the filter
all the main components of the machine; the cake, or the impermeable bulkhead (fine
front part is closed by a bulk head, which ground) or impregnated zone (coarse ground)
guarantees the separation between the which guarantees the transfer of -
excavation chamber (pressurized), housing couneterpressure to the excavation face.
the cutterhead, and the zone containing the Excavated debris by the tools on the rotating
machine components (unpressurized); cutterhead consists partly of natural soil and
_ longitudinal thrust jacks. partly of the bentonite or clay and water
Main field of application - Ground lacking mixture (slurry). This mixture is pumped
self-supporting capacity and with medium-low (hydraulic mucking) from the excavation
permeability (k ≤ 10 –4m/s). Presence of - chamber to a separation plant (which enables
groundwater. Higher permeability can be the bentonite/clay slurry to be recycled)
locally reduced by injecting bentonite slurry normally located on the surface.
onto the excavation face. The operating limit of Main components of the machine
the machine is the maximum pressure _ cutterhead (discs, blades or teeth);
applicable based on regulations for the use of _ protective shield containing all the main
compressed air in force in different countries. components of the machine; the front part is

III-5
 sealed by a bulkhead which guarantees the Thixshield: excavation using a roadheader
separation between the shield and the Hydrojetshield: excavation using high-pressure
excavation chamber (pressurized) containing water jets
the cutterhead; Main components of the machine – Similar to
_ longitudinal thrust jacks; those described for compressed air open
_ mud and debris separation system (normally shields.
located on the surface). Main field of application - Similar to that
Main field of application - Ground with limited described for the closed slurry shield.
self-supporting capacity. In granulometric -
terms, slurry shields are mainly suitable for 2.3.8. Earth Pressure Balance Shields
excavation in sand and gravels with silts. The
– EPBS
installation of a crusher in the excavation
chamber allows any lumps, which would not
2.3.8.1 Earth Pressure Balance Shields -
pass through the hydraulic mucking system to
EPBS.
be crushed. The use of disc cutters enables the
machine to excavate in rock. Polymers can be
Function principle - The
used to excavate ground containing much silt
cutterhead serves as the
and clay. Presence of groundwater.
means of excavation
whereas face support is
provided by the -
2.3.6.2 Hydroshields HS
excavated earth which is kept under pressure
inside the excavation chamber by the thrust
Function principle -
jacks on the shield (which transfer the pressure
Identical to that -
to the separation bulkhead between the shield
described for -
and the excavation chamber, and hence to the
uncompensated slurry
excavated earth).
shields; the only -
Excavation debris is removed from the
difference is the way of transferring the
excavation chamber by a screw conveyor
counterpressure to the face.
which allows the gradual reduction of pressure.
In the closed slurry shield in which the
Main components of the machine
counterpressure is compensated inside the
_ cutterhead: rotates with cutting spokes;
excavation chamber, in addition to the rotating
_ protective shield similar to that used for
head, there is always a metal buffer which
closed slurry shields;
creates a chamber partially filled with air
_ thrust system: longitudinal jacks which brace
connected to a compressor which can adjust
against the lining of precast segments.
the counterpressure at the face independent of
Main field of application - Ground with limited
the hydraulic circuit (supply of bentonite slurry
or no self-supporting capacity. In -
and mucking of slurry and natural ground)
granulometric terms, earth pressure balance
shields are mainly used for excavating in silts
Main components of the machine - Similar to
or clays with sand. The use of additives, such
those described for closed slurry shields with
as high-density mud or foams, enables
uncompensated counterpressure.
excavations in sandy-gravely soil.

2.3.8.2 .Special EPBS

2.3.7. Open slurry shields DK shield - Differs from the earth pressure
balance shield because of the geometry of the
Function principle - cutterhead whose central cutter projects further
It is identical to that than the cutters on the spokes, thus creating a
described for - concave cavity.
compressed air open Double shield (DOT shield) - These are two
shields. In this case face partially interpenetrated earth pressure balance
support is provided by slurry counterpressure. shields which operate simultaneously on the
Depending on the function of the cutterhead same plane, creating a “binocular” tunnel.
used, the following types can be identified: Flexible Section Shield Tunneling Method -

III-6
Earth pressure balance shield in which the Main field of application - The versatility of
excavation system is based on the presence of combined closed shields lends them to be used
several rotating cutterheads which enable the in rocks and soils under the groundwater table
construction of non-cylindrical sections. with limited or no self -supporting capacity.
Elliptical Excavation Face Shield Method -
Earth pressure balance shield in which the 3. Conditions for Tunnel
combined action of a circular cutterhead and Construction and Selection of TBM
additional cutters enables an elliptical section Tunneling Method
to be excavated.
3.1. Investigations
Triple Circular Face Shield Tunnel - This
consists of three shields, operating using earth 3.1.1. Introduction
or slurry pressure balance, which allow large
excavation sections to be constructed, such as In underground works, construction induces
those required to house an underground complex and often time-dependent soil-
railway station. structure interaction. Design must therefore
Vertical Horizontal Continuous Tunnel - This develop both of the basic aspects, which
is a slurry pressure balance TM consisting of a determine the interaction: statics of the
main shield, for shaft excavation, which excavation and the construction method
contains a spherical joint housing a secondary employed.
shield.
When the main shield has reached the The success of a project, in terms of time and
appropriate depth, the spherical joint is rotated costs, strongly depends on the method of
90_ and the secondary shield starts tunnel excavation employed and the timing of the
excavation. various construction phases.
Horizontal Sharp Edge Curving Tunnel -
Similar to the Vertical-Horizontal Continuous The planning of investigation and tests must
Tunnel, it enables the construction of two take into account these considerations and
tunnels intersecting at right angles. must be inserted into a well-defined design
Double Tube Shield Technology - This is a TM planning.
fitted with two concentric shields. The main
shield excavates the tunnel with the large Figure 3.1 shows the schematic structure of
section; the secondary shield then excavates the“Guidelines for Design, Tendering and
the tunnel with the smaller section. Construction of Underground Works adopted
by the main Italian Engineering Associations
2.3.9. Combined Shields: Mixshield, in relation to tunneling.
Polyshield These“guidelines”a r e based on the
identification of the“key points”and their
Function principle - The closed combined organization into“subjects”representing the
shield is a machine, which can be adapted to various successive aspects of the problem to be
different excavating conditions mainly by analyzed and quantified during design/ -
altering the excavation face support system. tendering/construction. The degree of detail of
The following combinations have already been each“key point”will depend on the -
used: Peculiarities of the specific project and design
l ) air pressure balance _ _ no pressure balance, stage.
2 ) slurry pressure balance _ _ no pressure In general planning for design, tendering and
balance, construction, as illustrated in Figure 3.2, the
3 ) earth pressure balance _ _ no pressure various“key points”and“subjects”are linked.
balance, The relationship between site investigations
Main components of the machine (Geological Survey and/or Geotechnical -
_ rotating cutterhead (rotates with cutter geomechanical studies) and the Preliminary
spokes more or less closed); design of excavation and support (Choice of
_ protective shield; excavation techniques and support measures) is
_ thrust system:longitudinal jacks. indicated.

III-7
 F gure 3.1 Schematic structure of the Guidelines for Design, Tendering and Construction of
Underground Works

1. Main Themes 2. Key points 3. Subjects

_ Functional Requirements
A1.General setting of the _ Design Constraints
works and its relationship _ Environmental Aspects
GENERAL _ Comparative analysis of
A with the general design alternative routes
SETTING OF THE
UNDERGROUND
WORK _ Collection and examination of
A2.Critical examination of technical documents
previous design stages
_ Assessment of the degree of
completeness of the design
A3.Codes and standards
_ General technical judgment of
A4.Reccommendations for project and recommendations
subsequent stages of _ Indication of possible design
design and construction adjustments
_ Considerations regarding possible
alternatives
_ Special conditions for tendering
and construction

B1.Acquisition of available _ Literature review

data
_ Structure
GEOLOGICAL _ Stratigraphy
B
SURVEY B2.Preliminary geological _ Geomorphology
model _ Hydrology and Hydrogeology

_ Evaluation of interaction with

B3.Site investigations geotechnical and geomechanical
investigations (C2)
_ Planning of site investigations
_ Structural geological setting
_ Meso – structural features
B4.Final geological model _ Lithostratigraohic features
_ Mineralogical and petrographic
features
_ Reliability of the qeoloqical model

_ Geomorphological setting
B5.Geomorphology
_ Interaction between
morphogenetic dynamics and
designed structures

_ General Hydrology and

B6.Hydrology and Hydrogeology
hydrogeology _ Water Chemistry
_ Structure acquifer interaction
_ Presence of other fluids
B7.Geothermal studies

B8.Seismicty _ Seismicity of the area and

neotectonic aspects

III-8
4. Main Themes 5. Key points 6. Subjects

_ Review of data from geological

study
C1.Preliminary _ Review of data from literature
GEOTECHNICAL l ti
C GEOMECHANICAL C2.Geotechnical and _ Evaluation of the relation-ship with
STUDIES geomechanical site investigation (B3)
investigations _ Planning of investigation and tests
_ Summary of results
_ Additional investigations

_ Soil and rock-mass structure

C3.Soil or rock mass _ Soil and intact rock
characterization characterization
_ Mechanical characterization of
discontinuities
_ Hydraulic properties of soil and
rock masses
_ Geomechanical classification of
rock masses
C4.Natural state of stress _ Geotechnical and geomechanical
models

D1.Subdivision of the route

into“homogeneous”zones
D PREDICTION OF
MECHANICAL
_ Calculation of behavior of face
BEHAVIOR OF THE D2.Evaluation of the excavation and profile of excavation without
MASSES stability conditions for each support
homogeneous zone

_ Effects of underground
D3.Surface and underground excavations on the surface
constraints _ Effects of excavation on the
surrounding mass
_ Effects of tunneling on the existing
hydrogeologic equilibrium

_ Study of different methods of

D4.Preliminary design of excavation and suppout:traditional
methods of excavation and and mechanized
support _ Choice of general criteria for
construction

III-9
 yp

_ Definition of applicable methods of

E1.Choice of excavation excavation
techniques and support _ Definition of section type
measures for each
_ Design of the stabilization
homogeneous zone
E DESIGN CHOICES interventions
AND CALCULATIONS _ Design loads
E2.Structural design _ Model of construction phases
_ Structural design of final lining
_ Design of finishing
_ Evaluation of the safety factors
E3.Evaluation of safety index _ Crisis scenarios and collapse
hypothesis
_ Definition of counter measures

_ Probabilistic evaluation of
E4.Design optimization construction times and costs of the
design solution

_ Design of portals
_ Ventilation systems
_ Monitoring plan
F1.Design of auxiliary works _ Disposal and borrow areas
_ Ancillary works
F DESIGN OF _ Construction sites and access
AUXILIARY WORKS roads
AND TENDER _ Environmental impact study

_ Technical documents which form

F2.Tender documents part of the contract
_ Plan of safety and coordination
_ Geological survey
_ Hydrogeological measurements
G MONITORING _ Geomechanical measurements
DURING G1.Monitoring during
construction _ Monitoring stress-strain response
CONSTRUCTION _ Monitoring the state of stress and
AND OPERATION strain in the lining
_ Effectiveness of consolidation and
stabilization measures
_ Monitoring nearby structures
above and below ground

_ Comparison between design

assumption and measurements
G2.Checking validity of during construction
design and abjustments
_ Adjustments of design according
during construction
to the observed differences
_ Structural auditing
G3.Auditing _ System auditing

_ Monitoring of stress and strain in

ground-stucture complex
G4.Monitoring during
operation _ Hydrogeological measurements
_ Surveys

III-10
 General setting of works
andits relationship with
the general design

Critical cxamination of
previous design stages

General setting of
Reccomandations for

underground works
Codes and standards sybsequent des.and cons.

Acquisition of available Pretiminary geological model Site investigation

Geomorphology Final geological model

Hydrology and hydrogeology

Geological
Geothermal studies

Preliminary cvaluation Geotechnical and geomechanical investigation Soil and rock mass
characterization

studies
In site stress

Geotechnical-
geomechanical
Evaluation of exacavation
Subdivision into stability for each
"homogencous"zones homogeneous zone methods of excavation and
support
Surface and underground
constraints

Prediction of mechanical
behavior of the masses
Choise of excavation
techniques and support Structural design Evalution of the safely index
measures

Design choise
and calculation
Design optimization

Design of auxiliary works and tender

Design of auxiliary works
documents Tender documents

Monitoring during construction and operation

Monitoring during Checking validity of
construction design and abjustments Auditing Monitoring during oprration

III-11
3.1.2. Parameter selection

In line with the general criteria discussed in the previous

section the parameters to be investigated for obtaining
useful information for mechanized tunnel design and
construction
have been divided in two categories:

1. geological parameters;
2. geotechnical - geomechanical parameters.

In the first category, the parameters are common to all

tunnel studies and/or design, not restricted to mechanized
tunneling (Table 3.1).

The geotechnical - geomechanical parameters

specifically to mechanized tunneling are
presented in Table 3.2.

In accordance also with the work carried out by the

French 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 in

Table 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 is

required, in terms of:

_ FS feasibility study/preliminary design

_ DD detailed design
_ DC construction stage

d) notes related to particular conditions.

III-12
 Table 3.1: Geological parameters and investigations required for the
design of mechanized tunnel excavation

No. OBJECTIVE OF INVESTIGATION INVESTIGATION TYPE

GEOLOGICAL
1 Regional structural setting Topography
2 Mesostructural and lithostratigraphic features Photogrammetry
Photointerpretation
Remote sensing
Regional geological studies and mapping
Detailed geological studies and mapping
3 Type of soils/rocks Detailed geological studies and mapping
Boreholes
4 Soils/rocks structure (fabric, stratification, Detailed geological studies and mapping
fracturing) Boreholes
5 Overburden and layers thickness , Detailed geological studies and mapping
6 Degree and depth of weathering Geophysical methods
Boreholes
7 Geological structural discontinuities (faults, Detailed geological studies and mapping
shear zones, crushed areas, main joints) Geophysical methods
Boreholes
8 Special formation (salt, gypsum, tale, organic Detailed geological studies and mapping ,
deposits) Boreholes
9 Karst phenomena: location of cavities, degree Detailed geological studies and mapping
of karstification, age and origin, infilling and Speleological studies
karst water Boreholes
Micro-gravimetric survey
GEOMORPHOLOGY
10 General geomorphological condition Topography
Photogrammetry
Photointerpretation
Regional geomorphological studies and mapping
Detailed geomorphological studies and mapping
11 Active or potentially active processes Detailed geomorphological studies and mapping
HYDROLOGY AND HYDROGEOLOGY
12 Hydrologic condition Topography
Photogrammetry
Photointerpretation
Regional hydrological studies and mapping
Detailed hydrological studies and mapping
Detailed geological studies and mapping
13 Groundwater features ( swampy ground areas, Detailed hydrogeological studies and mapping
springs or seepage position, notes on
groundwater properties )
14 No. of groundwater bodies, groundwater Detailed hydrogeological studies and mapping
levels ( and potential groundwater levels ) Boreholes
15 Soil/rock masses permeability types Detailed hydrogeological studies and mapping
GEOTHERMALCONDITIONS
16 Hydrotermal conditions Regional geological studies
17 Gas emanations Regional geological studies and mapping
Detailed geological studies and mapping
Boreholes
SEISMICDONDITIONS
18 Seismicity Regional geological studies

III-13
Table 3. 2: Geo- Par ameter s r elated to mechanized tunneling
Relationship with TBM excavation Stage of the work in which the
Tunnel face Excavation parameter is required
No. PARAMETER Symbol Mucking NOTE
and cavity
system
stability Cutting head Cutting tools FS DD DC
1 STATE OF STRESS
1.1 Natural stress σ1 , σ2 , σ3 , R A A-O
1.2 Vertical stress σv S/R S/R A N
1.3 Horizontal/Vertical total stress ratio Kt_(σh/σv) S/R A N
1.4 Horizontal/Vertical effective stress ratio KO S S/R A N N
1.5 Consolidation deg r e e (compaction, S A NO
decompr.)
2 PHYSICAL
2.1 Index properties
2.11 Volumetric weight γ, γd,γs, S/R S/R S/R A N-O A
2.12 Water content, saturation degree, void ratio w, Si, e S/R S/R S/R A N-O A
2.13 Plasticity index wl, wn S S A N-O A Absolutely necessary in soft
2.14 Granulometric characteristics S S/R S/R A N-O A ground
2.15 Activity S S S A N-O A
2.16 Mineralogic and petrographic features S/R A N-O A
2.2 Global evaluation quality
2.21 General quality index S/R S/R N-O
2.22 Alteration index AM R R R N-O N
2.23 Quality index tO R R R A-O

2.3 Discontinuities
2.31 Discontinuities density RQD,λ R R N-O N-O N
2.32 Number of sets Nl, NX R R A N-O N
2.33 Sets characteristics: R R A N-O N
_ Orientation (dip and dip direction)
_ Spacing
_ Persistence
_ Roughness
_ Aperture
_ Infilling
_ Seepage
_ Shear strength
_ Genesis (foliation, joint)

III-14
 Relationship with TBM excavation Stage of the work in which the
Tunnel face Excavation parameter is required
No. PARAMETER Symbol Mucking NOTE
and cavity
system
stability Cutting head Cutting tools FS DD DC
2.4 Weatherability
2.41 Sensibility to water, solubility S/R S/R S/R A N-O A
2.42 Sensibility to hydrometric variations S/R S/R S/R A N-O A Not frequently used
2.43 Sensibility to thermic variations S/R S/R A A
2.5 Water chemistry
2.51 Chemical characteristics S/R A N-O A
2.52 Waste conditions S/R N N
3 MECHANICAL
3.1 Strength
3.11 Shear (short time) τ S/R S/R S/R N(S) N-O A
3.12 Uniaxial compressive s f, σ c S/R S/R S/R N(R) N-O A
3.13 Tensile σt, IS R R R A-O N-O A
3.14 Residual S/R A A-O A
3.15 General strength index S/R S/R A
3.2 Global evaluation quality
3.21 Anisotropy elastic constants R R A A
3.22 Isotropic elastic constants E, υ S/R S/R N-O N-O A
3.23 Visco-behavior E(t), E(q) S/R A N-O A
3.24 Swelling S/R S/R N N-O A
3.3 Dynamic characteristics of soil/rock mass
3.31 P and S waves velocity S/R A N-O A
3.32 Deformability modules S/R A N-O A
3.33 Liquefaction potential S A N-O A
4 HYDROGEOLOGICAL
4.1 Anisotropy permeability kX, kV, kZ, S/R A-O
4.2 Isotropic permeability k S/R N-O N-O
4.3 Piezometric level, hydraulic gradient H, i S/R N N-O N-O
4.4 Water flow Q S/R S/R A-O N-O

III-15
 Stage of the work in which the
Relationship with TBM excavation parameter is required

No. PARAMETER Symbol Excavation NOTE

Tunnel face
Mucking
and cavity FS DD DC
system
stability
Cutting head Cutting tools

5 OTHER PARAMETERS
5,1 Abrasivity S/R S/R A-O N-O
5,2 Hardness R R A-O N-O All these parameters are particularly
5,3 Drillability R N-O required for mechanized tunneling
5,4 Sticky behavior S/R S/R S/R A-O N-O A
5,5 Ground friction S/R A A-O A-O

S=Soil; R=Rock
FS=Feasibility Study/Preliminary Design, DD=Detailed Design; DC=During Construction
N=Necessary; A=Advisable; O=Quantification of this parameter is done through specific tests

III-16
Ta b l e 3 . 3 : G e o - p a r a m e t e r s a n d r e l a t e d i nve s t i g a t i o n s
Lo cat ion
No S= sit e NOTE
PARAMETER INVESTIGATION TYPE L = =L a b .
.
1 STATE OF STRESS
1.1 Natural stress Borehole Slotter stressmeter method (R ) S In borehole test
Overcoring methods (R ) S In borehole test
S In borehole test
Hydraulic Fracturing Technique (R ) ' S Min. 5-6 tests are required, useful
also for soft rock
1.2 Vertical stress Dilatometer (S/R) S Experimental method
1.3 Horizontal/Vertical total stres s ratio Aedometer test with lateral pressure control L Not frequently used
(S) L Not frequently used
Triaxial test with lateral deformation control S Experimental method
(S) S
Dilatometer (S/R) S
1.4 Horizontal/Vertical effective stress ratio Flat jack method (R ) L
1.5 Consolidation degree (com action, Marchetti dilatometer (S) L
decompr.) Oedometric test (S)
Oedometric test (S)
2 PHYSICAL
2.1 Index properties
1.11 Unit weight Density tests (S/R) L
Gamma-densimeter (S) S
2.12 Water content, saturation degree, void Laboratory index tests (S/R) L
2.13 index Atterberg limits (S) L
2.14 Plasticity index Grain-size analyses and sedimentation L
Granulometric characteristics analyses (S) L
2.15 Petrographic analyses (R ) L
2.16 Activity Mineralogic analyses (S) L
Mineralogic and petrographic features Mineralogic analyses (S/R) L
Petrographic analyses (S/R) L
Chemical analyses (S/R)
2.2 Global evaluation of quality
2.21 Genera quality index Geophysical methods: .seismic, geoelectric, S
micro gravimetric, georadar (S/R)
Borehole perforation parameters: velocity, S Qualitative evaluation
torque, pressure (S/R)
2.22 Alteration index Visual examination of the material (R) S Outcrops, investigation galleries,
Slake durability test (R ) L borehole samples

III-17
 Lo_ation
No. PARAMETER INVESTIGATION TYPE S=site NOTE
L=Lab
2,23 Quality index Sonic waves test (R) L
Mineralogical analysis (R) L
Petrographic analysis (R) L
2,3 Discontinuities
2,31 Discontinuities density Site measurements (R) S Outcrop
Rock Quality Designation-RQD (R) S/L Borehole samples
Seismic _urvey(R) S Qualitative evaluation
2,32 Number of sets Site measurements + stereographic analyses (R) S/L
2,33 Sets characteristics:
1. Orientation (dip and dip direction) 1. Site measurement 1. S
2. Spacing 2. Site measurement 2. S
3. Persistence 3. Site measurement 3. S
_. Roughness 4. Site measurement 4. S
5. Aperture 5. Site measurement 5. S
6. Infilling 6. Site observation and_mineralogical test 6. S
7. Seepage 7. Site measurement 7. S
8. Shear strength 8. Shear test 8. L
9. Genesis (foliation, bedding, joint) 9. Geological observations 9. S
2,4 Weatherability
2,41 Sensitivity to water, solubility Site observation (S/R) S
Mineralogical analyses (S/R) L
Swelling test (R) L etc.)
Cyclic tests (wet-dry) (R) L
Solubility test (R) L
2,42 Sensibility to hygrometric variations Mineralogic analyses (S/R) L
Site observation (S/R) S
2,43 Sensibility to thermic variations Heating test (S/R) L
Freezing test (S/R) L
2,5 Water chemistry
2,51 Chemical characteristics Chemical analyses: salt content, aggressivity, L
hardness, pH value, temperature, etc.
2,52 waste conditions Chemical analyses L
3 MECHANICAL
3,1 Strength
3,11 Shear (short time) Casagrande shear box test, undrained conditions (S) S/L
Direct Shear test (R) L
In situ direct shear test (R) S
Triaxial test (S/R) S/L Soils : lower limit values ; rocks : upper limit values
Scissometer / Vane test (S) S/L In clayed borehole samples

III-18
 Location
No. PARAMETER INVESTIGATION TYPE S=site NOTE
L=Lab
3,12 Uniaxial compressive Uniaxial compression test (S/R) L
Point load test (R) S/L Indirect measurement of the parameter
3,13 Tensile Direct tensile test (R) L
Brazilian test (R) L Indirect measurement of the parameter
Point load test (R) S/L _ndirect measurement of the parameter
3,14 Residual Residual strength test (shear, triaxial tests) S/L
3,15 General strength index Borehole perforation parameter measurements:
velocity, torque, pressure (S/R)
3.,2 Deformability
3,21 Isotropic/Anisotropic el_stic constants Plate loading test (R/S) S Rock surface test
Directional dilatometer test (S/R) S Inside borehole tests
Uniaxial -Triaxial compressive tests on directional L
samples (S/R)
P-S wave measurement (_/R) S/L Qualitative measurement
Deformation measurement (S/R): S Rock surface test (i.e. experimental-
_. Convergence/dilatancy gallery)
2. Extensometer
3. Inclinome_ers
4. Settlements
3,22 Visco-behavior Flat jack method (R) S Rock surface test
Long-time plate loading test (R) S Rock surface test
Creep load test (S) L
Cycle dilatometer test (S/R) S Inside borehole tests
_eformation measurements (S/R) S Rock surface test
3,23 Swelling Swelling test (S/R) L/S
3,3 Dynamic characteristics of soil/rock mass
3,31 P and S waves velocity Seismic survey: cross-hole, down-hole S Inside borehole tes_s
3,32 Deformability modules Seismic survey: cross-hole, down-hole S Inside borehole tests
3,33 Liquefaction potential Standard penetration test S Inside borehole tests
4 HYDROGEOLOGICAL
4,1 Anisotropic permeability Observation during borehole drilling S Qualitative determination
Permeability tests: S Inside borehole teests
1. Lefranc
2. Lugeon
3. Directional, constant or variable water level

III-19
 Location
No. PARAMETER INVESTIGATION TYPE S=site NOTE
L=Lab
4.2 Isotropic permeability Pumping test S
Injection test S
4.3 Piezometric level, hydraulic gradient Piezometer (open type) S
Piezometer (close type) S
4.4 Water flow Tunnel measurements S
Springs measurements S
OTHER PARAMETERS
5.1 Abrasivity Abrasivity ISRM L
Cerchar test (R) L
Abrasivity (Norwegian Institure of Technology) L
LCPT test (S/R) L
5.2 Hardness Hardness ISRM (R) L
Schmith hammer (R) L
LCPT test L
Knoop S/L
Cone Indenter test (NCB) L
Punch test (Colorado Shool of Mines) L
Drop test (Norwegian Institute of Technology) L
Los Angeles test (S/R) L
5.3 Drillability Siever’s test L
Drillability tests L
5.4 Sticky behavior Mineralogical analyses (S/R) L Indirect measurement, related with
Atterberg limits (S) L physical index properties

III-20
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 REFERENCE
SITE INVESTIGATION
Topography,aerotopography,photogrammetry ISRM 1975
photointerpretation
Engineering geological investigations ISRM 1975
Geophysical methods:
_ micro-gravity
_ seismic
ASTM D4428-84
_ geoelectric
_ georadar
Drilling,borehore cameras and television
Trenches,shafts and galleries
SITE TEST
Plate loading test (R) ISRM11 / ISRM19 / ASTM D4394-84 / ASTM D4395-
Overcoring methods (R) 84
Flat jack method (R) ASTM D4623-86
Hydraulic fracturing method (R) ASTM D4729-87
Compression Test (R) ASTM D4645-87
Direct shear test (R) ASTM D4555-90
Dilatometer (S/R)
Standard penetration test: SPT (S) ASTM D4971-89 / ASTM D4506 -90
Cone penetration test: CPT (S) ASTM D1586-84 / ASTM D4633 - 86
Rock Quality Designation (RQD) ASTM D3441-86
Vane Shear Test (S)
Discontinuities (R) ASTM D2573-72
Deformation measurements (S/R): ISRM07 / ISRM14 / ASTM D4554 - 90
1. Convergence/dilatancy
2. Extensometer
3. Inclinometers
4. Settlements
Long-time plate bearing test (R)
Creep test (S/R)
Cycle dilatometer test (S/R) ASTM D4553-90
Deformation measurements (S/R)
Permeability tests:
1. Lefranc ASTM D2434-68
2. Lugeon
3. Directional, constant or variable, water level
Pumping test
Injection test
Piezometer (open type)
Piezometer (close type) ASTM D4750-87
Tunnel measurements

LABORATORY - SOIL
Identification tests : ASTM D4318-84 / ASTM D4254-83 / ASTM D3282-
_ Volumetric weights (natural, dry, satured) 88
_ natural water content, saturation degree ASTM D2487-90 / ASTM D4404-84 /
_ porosity, void ratio ASTM D4959-89 / ASTM D854-83
_ Atterberg limits ASTM D427-83 / ASTM D2210-90
_ Activity (clay)

III-21
 METHODS REFERENCE
Grain-size analyses and sedimentation analyses ASTM D422-63 / ASTM D2487-90 / ASTM D1140-54
Gamma-densimeter
Mineralogic analyses (diffractometer) ISRM 1977 / ASTM D4452-85
Chemical analyses
Permeability ASTM D2438-90
Oedometric test: ASTM D4186-90 / ASTM D2435-90 / ISRM 89
_ Natural consolidation ASTM D2435-90 / ASTM D2166-85
_ compressibility characteristics (consolidation
index, edometric compressibility index)
_ permeability
_ swelling pressure/ swelling index
swelling test (Huder-Amberg)
Shear test: ASTM D3080-90 / ASTM D2435-90
_ total coesion
_ total frictional angle
Triaxial test: ASTM D4767-88 / BS1377 / ASTM D2850-87
_ drained coesion
_ drained frictional angle
_ undrained coesion
_ total coesion
_ total frictional angle
LABORATORY - ROCK
Index laboratory tests: ISRM09
_ Density
_ natural water content
_ porosity
Slake durability test ISRM09 / ASTM D4644-87
Petrographic analyses ISRM01
Mineralogic analyses
Chemical analyses
Uniaxial compression test (R) ISRM08 / ASTM D3148-86 / ASTM D2938-86
Point load test (R) ISRM16 / ISRM25
Triaxial test (R) ISRM02 / ISRM13 / ASTM D2664-86
ASTM D4767 / BS1377 / AGI 1994
ISRM05 / ASTM D2936-84 / ASTM D3967-86
Direct Shear test (R) ISRM24
Direct tensile test (R)
Brazilian test (R)
Creep ASTM D4341-84 / ASTM D4406-84 / ASTM D4405-84
Sonic waves test (R) ASTM D2845-90 / ISRM03
Swelling test (R) ISRM09
Cyclic tests (wet-dry) (R)
Solubility test (R)
Thermal expansion test (S/R) ASTM D4611-86
Frozing test (S/R)
Abrasivity
_ Abrasivity ISRM04
_ Cerchar test (CAI index) West 1989
_ Abrasivity test (AV – AVS) NIT 1990
Hardness
_ Hardness ISRM04
_ Schmith hammer ISRM 1977
_ Knoop
_ Cone Indenter (INCB) National Coal Board, UK, 1964
_ Punch test
_ Los Angeles test (S/R)

III-22
 METHODS REFERENCE
Drillability
• Sievers test NIT 1990
• Drillability test
• Resistance to crushing : Drop test NIT 1990
LABORATORY - WATER
Chemical analyses:
_
• salt content / organic materials Standard Methods for examination of wa
• aggressivity _ waters. American Public Health Associa
• hardness
• pH value
• temperature

III-23
3.1.3. Monitoring during construction underground).

The deterministic design of a tunnel is based on 3.1.4. TBM tunneling monitoring system
judgment in selecting the most probable
values within the ranges of possible values of Monitoring systems are used to study the stress-strain
engineering properties. As construction - behavior of the surrounding ground and lining during
progresses the geotechnical - geomechanical conditions and after -
are observed, work performance is construction.
monitored and the design judgments can be evaluated
or, if necessary, updated. Thus, The use of a TBM for the construction of a tunnel does
engineering observations during tunnel works are often not permit continuous, direct
an integral part of the design process, observation of the ground being excavated.
and geotechnical - geomechanical - Therefore, all the necessary geological-
instrumentation is a tool, which assists with these geomechanical information required both during the
observations. construction phase for evaluating the ground conditions
ahead of the excavation face and subsequently for the
From a general point of view, the scope of the purpose of
monitoring scheme is to: documentation when the work is completed, are
normally obtained using indirect methods.
A. control the stability and stress - strain conditions of
the structures in the new underground construction; Usually the studies on the interaction between the
soil/rock mass and the TBM aim to
B. control the stability and stress-strain conditions of characterize the quality of the ground mass, above all,
the existing structures which potentially interfere with to assess its borability.
the new construction; and
However, the current problem is an inverse one: given
C. control ground movement around the new that there is no question that the ground
underground constructions; can be excavated, efforts must be focused on the
characterization itself through analysis and
D. monitor environmental aspects. elaboration of all construction parameters that could
possibly be recorded.
The design of the general monitoring scheme comprises
the following activities: Through precise and objective documentation of what
the TBM encounters during excavation
1. identification of the significant parameters which it is possible to derive the principal -
need to be monitored in consideration of: characteristics of the soil/rock mass because variations
_ construction geometries and materials; in TBM behavior are usually correlated with changes in
_ stability of existing structures (surface and/or the geotechnical-geomechanical
underground) and their potential situations.
interference with the new construction;
_ geotechnical – geomechanical parameters of the It is important to underline right from the outset that the
ground and their range of variation; prerequisites for making a correct
_ geo-structural calculations and structural analysis; evaluation of the ground mass using all the construction
and parameters that can possibly be
_ construction sequence. recorded may be summed up as follows:
_ the use of a TBM fitted with appropriate
2. definition of the adequate types of instruments; instrumentation.
_in this approach skilled engineering geologists with
3. specification of the caution and alarm values for each experience should be employed to collect and
parameter to be monitored; interpret all the relevant data.
_ The data collected should be stored in a dynamic
4. definition of the counter – measures in case that database so that multiple-parameter
caution and/or alarm leveis are exceeded. correlation can be not only established but also
The different investigation/monitoring possibilities are continuously updated in quasi-real time, as well as
_ from ground surface, or from underground offering the possibility to carry out ground conditions
_ before, during and after excavation. extrapolation and forecasting.
In the following subsections we will only examine the
underground investigation/- From a tunnel excavated by TBM it is possible to
monitoring systems specifically related to TBM investigate the ground ahead of the tunnel
tunneling (investigation before - face using the methods listed it Table 3.4.
excavation and monitoring during excavation from
III-24
The TBM monitoring systems which can be used to
collect data during tunnel construction are listed in
Table 3.5.

III-25
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 TBM
cutting head; inclined boreholes are normally possible immediately
behind the cutting head in open TBM, through the shield in shielded
TBM. Radial boreholes are possible in all TBM types through the
lining.
The objective of boreholes is to:
_ determine the lithological nature of the ground to be excavated
through 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 cutting
head. In the case of shielded TBMs, it is also possible to utilize
a“preventer”system to avoid the ingress of groundwater to the tunnel
during execution of the drilling.
Horizontal and/or inclined boreholes with core-recovery is not
commonly used because the time and drilling diameter required.
Boreholes without core recovery The method of no-core-recovery with registration of the following
drilling 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. The
diameter of the drill hole may be limited to 75mm, whereas the
drilling rods may be of the aluminum type in order to reduce potential
problems associated with the advance of the TBM later in the case
that the drilling rods might be completely lost in the drill hole.
Geostructural mapping of the face and/or The mapping must be performed using the same methodologies
of the sidewalls adopted for the face mapping in tunnels excavated by conventional
methods.

This type of investigation can be performed only when the TBM stops
excavation and thus it can be executed at more or less regular
intervals in function of the various construction needs. The mapping
involves the collection of all geological, structural and geomechanical
data of the soil/rock mass. The purpose of this kind of investigation
is:
_ 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 log
Neutron logs
Geoelectric logs
Seismic methods Tunnel Seismic Prediction method (TSP)
Soft Ground Sonic Probing System (SSP)

Table 3.5: TBM monitoring systems

III-26
 Category Parameter UdM TBMtype
Power kW

Cutting head
Torque Knm
Excavation

Thrust KN
Rotation speed RPM All TBM
Penetration rate mm/s
Cutting Consumption -
tools Wedge position mm

Air pressure kPa Closed slurry shield (hydroshield)

Support in the

Compressed air close shield

excavation

Air discharge m3/h

chamber

Slurry pressure kPa

Closed slurry shield
Slurry level mm
Earth pressure kPa Earth pressure balance shield

Slurry discharge m3/h

Slurry density kg/dm3
Closed slurry shield
Amount

Discharge m3/h
Density kg/dm3
Mucking

Weight kN Unshielded, single-double shielded TBM, mec.

Amount m3 supported, comp. air, closed slurry and EPB shields

Petrographic characteristics -
Charact.

All TBM (in slurry shield or EPB

Grain-size distribution - shield TBM is not required)
mechanical parameters -

Shield position (x y z) m All TBM

Gripper thrust kN Open TBM and some double
Gripper stroke mm shielded TBM
Other parameters

Jack thrust kN Single-double shielded TBM, mec. suppoted, comp.

Jacks stroke mm air, closed slurry and EPB shields TBM

Injection (through the shield) pressure kPa

Closed slurry and EPB shield
Injection (through the shield) amount m3
Concrete injection pressure kPa Shielded TBM with extruded
Concrete injection amount m 3 concrete lining system

Excavation cycle (min. - med. - max.) h

Performance

Advance rate per shift/day/week/month m

Lining rings per shift/day/week/month N°

Planned (holidays, tools change, other ordinary
Construction data

maintenance) h
Due to machine problem (mechanical, electrical, etc.) h
All TBM
Due to unpredicted rock mass behavior, (water inflow,
TBM stops

tunnel face and /or cavity instabilities, squeezing ground,

karst, etc.) h
Due to lining problems h
Diverse (back-up problems, others) h
Due to mucking system problems (slurry circuit, screw
conveyor, belt conveyor, muck cars, etc.) h

III-27
4. REFERENCES D2216-90“Water (Moisture) Content of Soil,
Rock, and Soil-Aggregate -
A) ASTM (American Society for Testing Mixtures, Laboratory -
Materials) Determination of ...”.
D4452-85“X-Ray Radiography of Soil -
D4750-87“Subsurface Liquid Levels in a Samples”.
Borehole or Monitoring Well D4341-84“Creep of Cylindrical Hard Rock
(Observation Well ) , Core Specimens in Uniaxial
Determining”. Compression”.
D1140-54“Amount of Material in Soils Finer D4406-84“Creep of Cylindrical Rock Core
than the No. 200 (75-_m) Sieve”. Specimens in Triaxial -
D4428-84“Crosshole Seismic Testing”. Compression”.
D2487-90“Classification o f Soils for D4405-84“Creep of Cylindrical Soft Rock
Engineering Purposes”. Core Specimens in Uniaxial
D2166-85“Compressive Strength, Unconfined, Compression”.
of Cohesive Soil”. D4555-90“Deformability and Strength of
D4767-88“Consolidated-Undrained Triaxial Weak Rock by Conducting an In
Compression Test on Cohesive Situ Uniaxial Compressive Test,
Soils”. Determining”.
D4404-84“Determination of Pore Volume and D497l-89“Determining the In Situ Modulus of
Pore Volume Distribution of Soil Deformation of Rock Using
and Rock by Mercury Intrusion Diametrically Loaded 76-mm (3-
Porosimetry”. in.) Borehole Jack”.
D4959-89“Determination of Water (Moisture) D2936-84“Direct Tensile Strengh of Intact
Content of Soil by Direct Heating Rock Core Specimens”.
Method”. D3148-86“Elastic Moduli of Intact Rock Core
D4829-88“Expansion Index of Soils”. Specimens in Uniaxial -
D2573-72“Field Vane Shear Test in Cohesive Compression”.
Soil”. D4553-90“In Situ Creep Characteristics of
D4318-84“Liquid Limit, Plastic Limit, and Rock,Determining”.
Plasticity Index of Soils”. D4554-90“In Situ Determination of Direct
D2435-90“One-Dimensional Consolidation Shear Strength of Rock -
Properties of Sails”. Discontinuities”.
D4186-90“One-Dimensional Consolidation D4395-84“In Situ Modulus of Deformation of
Properties o f Soils Using Rock Mass Using the Flexible
Controlled-Strain Loading” . Plate Loading Method,
D2434-68“Permeability of Granular Soil Determining”.
(Constant Head)”. D4506-90“In Situ Moudulus of Deformation
D4719-87“Pressuremeter Testing in Soil”. of Rock Mass Using a Radial
D2844-89“Resistance R-Value and Expansion Jacking Test, Determining”.
Pressure of Compacted Soils”. D4394-84“In Situ Modulus of Deformation of
D427-83 “Shrinkage Factors of Soils”. Rock Mass Using the Rigid Plate
D854-83 “Specific Gravity of Soils”. Loading Method, Determining”.
D2850-87“Unconsolidated,Undrained D4623-86“In Situ Stress in Rock Mass by
Compressive Strength of Cohesive Overcoring Method - USBM
Soils of Cohesive Soils in Triaxial Borehole Deformation Gage,
Compression”. Determination of ...”.
D3441-86“Deep, Quasi-Static, Cone and D4729-87“In Situ Stress and Modulus of
Friction-Cone Penetration Tests Deformation Determination Using
of Soil”. the Flat jack Method”.
D3080-90“Direct Shear Test of Soils Under D4645-87“In Situ Stress in Rock Using the
Consolidated Drained - Hydraulic Fracturing Method”.
Conditions”. D4644-87“Slake Durability of Shales and
D422-63“Particle-Size Analysis of Soils”. Similar Weak Rocks”.

III-28
D4611-86“Specific Heat of Rock and Soil”. 1978, International Journal of Rock
D3967-86“Splitting Tensile Strength of Intact Mechanics, Mining Sciences and
Rock Core Specimens”. Geomechanical Abstract, vol. 15,
D2664-86“Triaxial Compressive Strength of n_6, pp. 319-368.
Undrained Rock Core Specimens ISRM08“Suggested methods for determining
Without Pore Pressure - the uniaxial compressive strength and
Measurements”. deformability of rock materials”.
D2938-86“Unconfined Compressive Strength 1979, International Journal of Rock
of Intact Rock Core Specimens”. Mechanics, Mining Sciences and
D2845-90“Laboratory Determination of Pulse Geomechanical Abstract, vol.
Velocities and Ultrasonic Elastic 16,n_2,pp. 135-140.
Constants of Rock”. ISRM09“Suggested methods for determining
water content, porosity, density,
B) ISRM (International Society of Rock absorption, and related properties and
Mechanic) swelling and slake-durability index
properties”. 1979, International
ISRM01“Suggested methods for petrographic Journal of Rock Mechanics,Mining
description of rocks”. 1978, Sciences and Geomechanical -
International Journal of Rock Abstract, vol. l6, n_2, pp. 141-l56.
Mechanics. Mining Sciences and ISRM10“Suggested methods for determining
Geomechanical Abstract,vol. 15, in situ deformability of rock”. 1979,
n_2,pp. 41-46. International Journal of Rock
ISRM02“Suggested methods for determining Mechanics, Mining Sciences and
strength of rock materials in triaxial Geomechanical Abstract, vol.
compression”. 1978, International 16,n_3,pp. 195-214.
Journal of Rock Mechanics, Mining ISRM11“Suggested methods for pressure
Sciences a n d Geomechanical monitoring using hydraulic cells”.
Abstract, vol.15, n_2, pp. 47.52. 1980, International Journal of Rock
ISRM03“Suggested methods for determining Mechanics, Mining Sciences and
sound velocity”. 1978,International Geomechanical Abstract, vol. 17,
Journal of Rock Mechanics, Mining n_2, pp. 117-128.
Sciences a n d Geomechanical ISRM12“Suggested methods for geophysical
Abstract, vol.15,n_2, pp. 53-58. logging of boreholes”. 1981,
ISRM04“Suggested methods for determining International Journal of Rock
hardness and abrasiveness of rocks”. Mechanics, Mining Sciences and
1978, International Journal of Rock Geomechnical Abstract,
Mechanics, Mining Sciences and vol.18,n_1,pp.67-84.
Geomechanical Abstract, vol.15,n_2, ISRM13“Suggested methods for determining
pp. 89-98. the strength of rock materials in
ISRM05“Suggested methods for determining triaxial compression: revised -
tensile strength of rock materials”. version”. 1983, International Journal
1978,International Journal of Rock of Rock Mechanics, Mining Sciences
Mechanics, Mining Sciences and and Geomechanical Abstract, vol. 20,
Geomechanical Abstract, vol. n_6, pp. 283-290.
15,n_2,pp.-99-104. ISRM14“Suggested methods for surface
ISRM06“Suggested methods for monitoring monitoring move me nt s across
rock movements using borehole discontinuities”. 1984, International
extensometers”. 1978, International Journal of Rock Mechanics, Mining
Journal of Rock Mechanics, Mining Sciences and Geomechanical -
Sciences and Geomechanical - Abstract, vol. 21 , n_5, pp. 265-276.
Abstract, vol. 15, n_6, pp. 305-318. ISRM15“Suggested methods for pressure
ISRM07“Suggested m e t h o d f o r the monitoring using hydraulic cells”.
quantitative description of - 1985, International Journal of Rock
discontinuities in rock masses”. Mechanics, Mining Sciences and

III-29
 Geomechanical Abstract, vol. 22, 1987, “Guidelines for Good Tunneling
n_2, pp. 51-60. Practice”.
ISRM16“The equivalent core diameter method
of size and shape correction is point BTS (British Tunneling Society), 1997,
load testing”. 1985, International “Model Specification for Tunneling”.
Journal of Rock Mechanics, Mining
Sciences a n d Geomechanical AFTES (Association Francaise des Travaux en
Abstract, vol. 22, n_2, pp. 61-70. Souterrain)
ISRM17“Suggested methods f o r rock
anchorage testing”. 1985, _Text of recommendations for a description
International Journal of Rock of rock masses useful for examination the
Mechanics, Mining Sciences and stability of underground works (Working
Geomechanical Abstract,vol. 22, n_2, Group n . l : Geology-geotechnical
pp. 71-84. engineering). 1993;
ISRM18“Suggested methods for deformability
determination using a large flat jack _Proposals concerning the measurements
technique”. 1986, International and testing to be performed in connection
Journal of Rock Mechanics, Mining with a me c ha ni c a l c ut t i ng :
Sciences and Geomechanical - characterization of rocks and soils
Abstract, vol. 23, n_2, pp.131-140. (Working Group n.4: Mechanized
ISRM19“Suggested methods f o r rock excavation), 1993.
determination”. 1987, International SIG (Società Italiana Gallerie), 1997,
Journal of Rock Mechanics, Mining “National Project for Design and
Sciences a n d Geomechanical Construction Standards in Underground
Abstract, vol. 24, n_ 1, pp. 53-74. Works Guidelines for Design, Tendering
ISRM20“Suggested methods for deformability and Construction of Underground Works”,
determination using a flexible Gallerie e Grandi Opere Sotterranee,
dilatometer”. 1987, International marzo 1997.
Journal of Rock Mechanics, Mining AGI (Associazione Geotecnica Italiana), 1977,
Sciences a n d Geomechanical “Raccomandazioni sulla programmazione
Abstract, vol. 24, n_2, pp. 123-134. ed esecuzione delle indagini geotecniche”.
ISRM21“Suggested methods for determining AGI (Associazione Geotecnica Italiana),1994,
the fracture toughness or rock”. 1988, “Raccomandazioni sulle prove -
International Journal of Rock geotecniche di laboratorio”.
Mechanics, Mining Sciences and SIA (Société Suisse des Ingégneurs et des
Geomechanical Abstract, vol. 25, n_2, Architects), 1975, “Norma 199 conoscenza
pp. 71-96. dei massicci rocciosi n e i lavori
ISRM22“Suggested methods for seismic sotterranei”. Zurich.
testing within and between SIA (Société Suisse des Ingégneurs et des
boreholes”. 1988, International Architects),1993, “NORMA 198 Lavori in
Journal of Rock Mechanics, Mining sotterraneo”. Zurich.
Sciences and Geomechanical -
Abstract, vol. 25, n_6, pp. 447- 472.
ISRM23“Suggested methods for deformability AUSTRIAN NORM, 1983, “ONORM
determination using a large flat jack 2203”and “VORNORM 2203”, 1975.
technique”.
ISRM24“Suggested methods for determing DEUTSCHER AU S S C H U S S FÜR
Shear Strength”. February 1974. UNTERIRDISCHES BAU E N : DAUB;
ÖSTERREICHISCHE
GESELLSCAFT FÜR GEOMECHANIK
UND ARBEITSGRUPPE TUNNELBAU
C) OTHER REFERENCES DER FORSCHUNGESELLSCHAFT FÜR
DAS VERKEHRS – UND -
ITA (International Tunneling Association), STRASSENWESEN: FACHGRUPPPE

III-30
 FÜR UNTERTAGEBAU DES -
SCHWEIZERISCHEN INGENIEUR - UND
ARCHITEKTENVHREIN,
1996, Empefelung zur Auswal und
Bewentung von Tunnelvotriebsmachinen.
Vol. Spec.

GEHRING K.H., 1995, “Deciding about

Range of Application for Shield System,
Prerequisites,Concepts, Examples”. Atti
della giornata d i studio: “Scavo
meccanizzato integrale delle gallerie.
Progettazione integrata e criteri di scelta
delle macchine”. Roma.

NATIONAL COAL BOARD (NCB), 1964,

“Methods of assessing rock cuttability”,
C.E.E. Report, N_ 65 ( 1 ).

NIT - NORWEGIAN INSTITUTE OF

TECHNOLOGY, 1988, “Hard rock tunnel
boring”. General Report.

NIT - NORWEGIAN INSTITUTE OF

TECHNOLOGY, 1990, “Drillabilily, drilling
rate index catalogue”, PR 13.90 University
of Trondheim.

PACHER F., RABCEWICZ L.V., GOLSER J.,

1974, Zum derzeitigem Stand der
Gebirgsklassifizierung in Stollen - und
Tunnelbau. Preference S 1-8.

III-31
 A FTES
N E W REC O M ME N D ATI O N S O N
CH O OSIN G MECHA NIZED TUN NELLIN G TECH NIQ UES

A .F.T.E.S. will be ple ased to receive any suggestions concerning these recommend ations

Version 1 - 2 0 0 0 -a pproved by the Technical C ommittee of 2 3 N ovember 1 9 9 9 Translated in 2 0 0 0

TEXT PRESENTED BY
P. L O N G C H AMP, M O D ERAT O R O F A F TE S W O RK G R O U P N O . 4 - TE C H NIC AL MA N A G ER, U N D ER G R O U N D W O RK S -
B O U Y G U E S TRAVA UX P U BLIC S
WITH TH E ASSISTA N C E O F
A. S C H W E N Z F EIER, C ETU
TH E S E S U B G R O U PS W ERE M O D ERATE D B Y
J.M. D E M O RIE UX, S ETE C - F. MA UR O Y, SYSTRA - J.M. R O G E Z, RATP - J.F. R O U BIN ET, G TM
TH E S E RE C O MM E N DATIO N S W ERE DRAW N U P B Y A N U M B ER O F S U B W O RK G R O U PS W H O S E M E M B ERS W ERE:
A. AM EL O T, SPIE B ATIG N O LLE S - D. A N DRE, S N C F - A. B ALA N, S N C F - H. B EJUI = , A F TE S -
F. B ERTRA N D, C H A NTIERS M O D ERN E S - F. B O RDA C H AR, Q UILLERY - P. B O UTIG N Y, C AMP E N O N B ERN ARD S G E -
L. C H A NTR O N, C ETU - D. C U ELLAR, S N C F - J.M. F RE D ET, SIM E C S O L - J.L. GIA F F ERI, E D F- G D F -
J. G UILLA U M E, PIC O G R O U P E RA Z EL - P. J O VER, S.M.A.T. - C H. M O LIN E S, F O U G ER O LLE S B ALL O T -
P. RE N A ULT, PIC O G R O U P E RA Z EL - Y. RE S C AMPS, D E S Q U E N N E ET GIRAL
A C K N O WLE D G E M E NTS ARE D U E T O TH E F O LL O WIN G F O R C H E C KIN G THIS D O C U M E NT:
M. MARE C , MIS O A - M. C . MIC H EL, O PP B TP - P. B ARTH E S, A F TE S

I N TR O D U CTI O N

T
he first recommendations on mecha- has picked up on trends from the east most appropriate mechanized tunnelling
nized tunnelling techniques issued in (Germany and Japan). method, but rather that they could pro-
1986 essentially concerned hard-
Faced with France’s extremely varied vide a document which:
rock machines. geology, project owners, contractors, 1) clarifies the different techniques, des-
The shape of the French market has chan- engineers, and suppliers have adapted
ged a great deal since then. The deve- cribing and classifying them in different
these foreign techniques to their new
lopment of the hydropower sector which conditions at astonishing speed. groups and categories,
was first a pioneer, then a big user of Now, this new French technical culture is 2) analyzes the effect of the selection cri-
mechanized tunnelling methods has pea- being exported throughout the world teria (geological, project, environmental
ked and is now declining. In its place, tun- (Germ an y, Egypt, United Kingdom, aspects, etc.),
nels now concern a range of generally Australia, China, Italy, Spain, Venezuela,
urban works, i.e. sewers, metros, road 3) highlights the special features of each
Denmark, Singapore, etc.).
and rail tunnels. technique and indicates its standard
This experience forms the basis for these
Since most of France’s large urban scope of application, together with the
recommendations, drawn up by a group
centres are built on the flat, and often on of 25 professionals representing the dif- possible accompanying measures.In
rivers, the predominant tunnelling tech- ferent bodies involved. other words, these new recommenda-
nique has also switched from hard rock Before the large number of parameters tions do not provide ready- made ans-
to loose or soft ground, often below the and selection criteria, this group soon wers, but guide the reader towards a rea-
water table. realized that it was not possible to draw soned choice based on a combination of
To meet these new requirements, France up an analytical method for choosing the technical factors.

Beaumont machine, 1882. First attempt to drive a tunnel beneath the English Channel.
IV-1
 Choosing mechanized tunnelling techniques

1.PURPOSE O F THESE REC O MMENDATIO NS 3 6.2.2. Specific features of open- face segmental shield 13
TBMs
2. MECHA NIZED TUN NELLIN G TECH NIQ UES 3
6.2.3. Specific features of double shield TBMs 13
2.1. Definition and limits 3
6.3. Specific features of TBMs providing immediate frontal 13
2.2. Basic functions 3
and peripheral support
2.2.1. Excavation 3
6.3.1. Specific features of mechanical- support shield TBMs 13
2.2.2. Support and opposition to hydrostatic pressure 3
6.3.2. Specific features of compressed- air TBMs 13
2.2.3. Mucking out 3
6.3.3. Specific features of slurry shield TBMs 13
2.3. Main risks and advantages of mechanized tunnelling 3
6.3.4. Specific features of earth pressure balance 14
techniques
machines
3. CLASSIFICATIO N O F MECHA NIZED TUN NELLIN G TECH- 4
7. APPLICATIO N O F MECHA NIZED TUN NELLIN G TECH- 14
NIQ UES
NIQ UES
4. DEFINITIO N O F THE DIFFERENT MECHA NIZED TUN NEL- 4 7.1. Machines not providing immediate support 14
LIN G TECH NIQ UES CLASSIFIED IN CHAPTER 3
7.1.1. Boom- type tunnelling machines 14
4.1. Machines not providing immediate support 4
7.1.2. Main- beam TBMs 15
4.1.1. General 4
7.1.3. Tunnel reaming machines 15
4.1.2. Boom- type tunnelling machine 4
7.2. Machines providing immediate peripheral support 15
4.1.3. Main- beam TBM 4
7.2.1. Open- face gripper shield TBMs 15
4.1.4. Tunnel reaming machine 5
7.2.2. Open- face segmental shield TBMs 15
4.2. Machines providing immediate support peripherally 6
7.2.3. Open- face double shield TBMs 15
4.2.1. General 6
7.3. Machines providing immediate frontal and peripheral 15
4.2.2. Open- face gripper shield TBM 6 support
4.2.3. Open- face segmental shield TBM 6 7.3.1. Mechanical- support shield TBMs 15
4.2.4. Double shield 7 7.3.2. Compressed- air TBMs 15
4.3. Machines providing immediate peripheral and frontal 7 7.3.3. Slurry shield TBMs 16
support simultaneously
7.3.4. Earth pressure balance machines 16
4.3.1. General 7
4.3.2. Mechanical- support TBM 8. TECH NIQ UES ACC O MPA NYIN G MECHA NIZED TUN NEL- 16
7
LIN G
4.3.3. Compressed- air TBM 8
8.1. Preliminary investigations from the surface 16
4.3.4. Slurry shield TBM 8
8.1.1. Environmental impact assessment 16
4.3.5. Earth pressure balance machine 9
8.1.2. Ground conditions 16
4.3.6. Mixed- face shield TBM 9
8.1.3. Resources used 16
5.EV ALUATIO N O F PARAMETERS F OR CH OICE O F MECHA- 10 8.2. Forward probing 16
NIZED TUN NELLIN G TECH NIQ UES
8.3. Ground improvement 17
5.1. General 10
8.4. Guidance 17
5.2. Evaluation of the effect of elementary selection para- 10
meters on the basic functions of mechanized tunnelling tech- 8.5. Additives 17
niques 8.6. Data logging 18
5.3. Evaluation of the effect of elementary selection para- 11 8.7. Tunnel lining and backgrouting 18
meters on mechanized tunnelling solutions 8.7.1. General 18
6. SPECIFIC FEATURES O F THE DIFFERENT TUN NELLIN G 12 8.7.2. Lining 18
TECH NIQ UES 8.7.3. Backgrouting 18
6.1. Machines providing no immediate support 12 9. HEALTH A ND SAFETY 18
6.1.1. Specific features of boom- type tunnelling machines 12 9.1. Design of tunnel boring machines 18
6.1.2. Specific features of main- beam TBMs 12 9.2. Use of TBMs 19
6.1.3. Specific features of tunnel reaming machines 12
6.2. Specific features of machines providing immediate per- APPENDIX 1 20
12
ipheral support APPENDIX 2 21
6.2.1. Specific features of open- face gripper shield TBMs 12 APPENDIX 3 24

IV-2
 - Choosing mechanized tunnelling techniques
1 - P U RP O SE O F T H ESE in which excavation is performed mechani- process (segmental lining for instance). This
REC O M M E N D A TI O N S cally by means of teeth, picks, or discs. The aspect has been examined in other AFTES
recommendations therefore cover all (or recommendations and is not discussed fur-
These recommendations supersede the pre- nearly all) categories of tunnelling machines, ther here.
vious version which was issued in 1986 and ranging from the simplest (backhoe digger) Recent evolution of mechanized tunnelling
which dealt essentially with hard- rock or to the most complicated (confinement-type techniques now enables tunnels to be driven
“main- beam” tunnel boring machines shield TBM). in unstable, permeable, and water- bearing
(TBMs).
The mechanized shaft sinking techniques ground without improving the ground befo-
The scope of this revised version has been that are sometimes derived from tunnelling rehand. de ceux-ci.This calls for constant
broadened to include all (or nearly all) types techniques are not discussed here. opposition to the hydrostatic pressure and
of tunnelling machines. potential water inflow. Only confinement-
For drawing up tunnelling machine supply
The recommendations are intended to serve contracts, contractors should refer to the pressure techniques meet this requirement.
as a technical guide for the difficult and often recommendati ons of AFTES WG 17,
i rreversible choice of a tunnel boring 2 . 2 . 3 - M uc k i n g o u t
“Pratiques contractuelles dans les travaux
machine consistent with the expected geolo- souterrains ; contrat de fourniture d’un tun- Mucking out of spoil from the tunnel itself is
gical and hydrogeological conditions, the nelier” (Contract practice for underground not discussed in these recommendations.
environment, and the type of the tunnel pro- works; tunnelling machine supply contract) However, it should be recalled that mucking
ject. (TOS No. 150 November/December 1998). out can be substantially affected by the tun-
To start with, the different kinds of machines nelling technique adopted. Inversely, the
are classified by group, category, and type. constraints associated with mucking opera-
2 . 2 - B A SIC F U N CTI O N S
Since all the machines share the common tions or spoil treatment sometimes affect the
characteristic of excavating tunnels mecha- choice of tunnelling techniques.
nically, the first criterion for classification is 2 . 2 . 1 - E x c a v a ti o n
The basic mucking-out techniques are:
naturally the machine's ability to provide
Excavation is the primary function of all these • haulage by dump truck or similar
immediate support to the excavation.
techniques.
This is followed by a list of the parameters • haulage by train
The two basic mechanized excavation tech-
which should be analyzed in the selection • hydraulic conveyance system
niques are:
process, then by details of the extent to which
these parameters affect mechanized tunnel- • Partial-face excavation • pumping (less frequent)
ling techniques, and finally a series of fun- • Full- face excavation • belt conveyors
damental comments on the different kinds of
machine. With partial- face excavation, the excavation
equipment covers the whole sectional area 2 . 3 - M A I N RIS K S A N D
By combining these parameters, decision- A D V A N TA G ES O F
of the tunnel in a succession of sweeps across
makers will arrive at the optimum choice.
the face. M E C H A N I Z E D T U N N ELLI N G
The principal specific features of the different TE C H N I Q U ES
groups and categories of techniques are then With full-face excavation, a cutterhead -
outlined, and the fundamental fields of appli- generally rotary - excavates the entire sec-
tional area of the tunnel in a single opera- The advantages of mechanized tunnelling
cation of each category are explained. are multiple. They are chiefly:
tion.
Lastly, accompanying techniques, which are • enhanced health and safety conditions for
often common to several techniques and vital 2 . 2 . 2 - Su p p o rt a n d o p p o siti o n t o the workforce,
for proper operation of the machine, are lis- h y d r o st a tic p r e ss u r e
ted and detailed. It should be noted that data • industrialization of the tunnelling process,
logging techniques have meant remarkable Tunnel support follows excavation in the hie- with ensuing reductions in costs and lead-
progress has been made in technical analy- rarchy of classification. times,
sis of the problems that can be encountered. “Support” here means the immediate sup- • the possibility some techniques provide of
Since health and safety are of constant port provided directly by the machine (where crossing complex geological and hydrogeo-
concern in underground works, a special applicable). logical conditions safely and economically,
chapter is devoted to the matter. A distinction is made between the techniques • the good quality of the finished product
providing support only for the tunnel walls, (surrounding ground less altered, precast
roof, and invert (peripheral support) and concrete lining segments, etc.)
2 - M EC H A N I Z ED TU N N EL- those which also support the tunnel face (per- However, there are still risks associated with
LI N G TEC H N I Q U ES ipheral and frontal support). mechanized tunnelling, for the choice of
There are two types of support: passive and technique is often irreversible and it is often
2 . 1 - D EFI N ITI O N A N D active. Passive or “open- face” support reacts impossible to change from the technique first
passively against decompression of the sur- applied, or only at the cost of immense
LI M ITS rounding ground. Active or “confinement- upheaval to the design and/or the econo-
For the purposes of these recommendations, pressure” support provides active support of mics of the project.
“mechanized tunnelling techniques” (as the excavation. Detailed analysis of the conditions under
opposed to the so- called “conventional” Permanent support is sometimes a direct and which the project is to be carried out should
techniques) are all the tunnelling techniques integral part of the mechanized tunnelling substantially reduce this risk, something for

IV-3
 Choosing mechanized tunnelling techniques
which these recommendations will be of into categories and types. sweeps of the arm. Consequently the faces
great help. The experience and technical they excavate can be both varied and
skills of tunnelling machine operators are variable. The penetration force of the tools is
also an important factor in the reduction of 4 - DEFI N ITI O N O F T H E DIF- resisted solely by the weight of the machineLa
risks. réaction à.
FERE N T M EC H A N I Z ED TU N -
N ELLI N G TEC H N I Q U ES This group of machines is fitted with one of
three types of tool:
3 - CL A SSIFIC A TI O N O F CL A SSIFIED I N C H A PTER 3
•Backhoe, ripper, or hydraulic impact brea-
M EC H A N I Z ED TU N N ELLI N G ker
TEC H N I Q U ES 4 . 1 - M A C H I N ES N O T
• In-line cutterhead (roadheader)
P R O V I D I N G I M M E D I AT E
It was felt to be vital to have an official clas- • Transverse cutterhead (roadheader)
sification of mechanized tunnelling tech-
S U P P O RT
AFTES data sheets: No. 8 – 14 (photo 4.1.2)
niques in order to harmonize the termino-
logy applied to the most common methods. 4.1.1 - G eneral
4 . 1 . 3 - M a i n - b e a m TB M
The following table presents this classifica- Machines not providing immediate support
A main- beam TBM has a cutterhead that
tion. The corresponding definitions are given are necessarily those working in ground not
excavates the full tunnel face in a single pass.
in Chapter 4. requiring immediate and continuous tunnel
support. The thrust on the cutterhead is reacted by
The table breaks the classification down into
bearing pads (or grippers) which push
groups of machines (e.g. boom- type unit) on
4 . 1 . 2 - B o o m -t y p e t u n n e lli n g radially against the rock of the tunnel wall.
the basis of a preliminary division into types
m a ch i n e
of immediate support (none, peripheral, per- The machine advances sequentially, in two
ipheral and frontal) provided by the tunnel- Boom- type units (sometimes called “tunnel phases:
ling technique. heading machines”) are machines with a • Excavation (the gripper unit is stationary)
To give more details on the different tech- selective excavation arm fitted with a tool of
some sort. They work the face in a series of • Regripping
niques, the groups are further broken down

*F or 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.

CLA SSIFICA TION OF MECHA NIZED TUNNELLING TECHNIQUES

IV-4
 - Choosing mechanized tunnelling techniques
➀
➁ ➂

➃ ➄
➀ Transverse cutterhead
➁ B oom ➃ Loading apron
➂ Muck conveyor ➄ Crawler chassis
Phot o 4 .1 .2 - Roadheader
Schéma 4 .1 .2

Spoil is collected and removed rearwards by

the machine itself.
This type of TBM does not play an active role
in immediate tunnel support.
AFTES data sheets: No. 1 to 7, 10 to 13, 15 Phot o 4 .1 .3 - Lesot ho Highlands Wat er Project
to 24, 26 to 30, 67(photo 4.1.3)

➀ ➂ ➁ ➃ ▼

➀ C anopy/Hood/Roof
➁ Rear gripper
➂ Front gripper
➃ Muck conveyor
➄ Rear lift leg
➄

4 . 1 . 4 - Tu n n e l r e a m i n g m a ch i n e
A tunnel reaming machine has the same basic functions as
a main-beam TBM. It bores the final section from an axial
tunnel (pilot bore) from which it pulls itself forward by ▼
means of a gripper unit.

➄ ➂ ➁ ➀

➀ Pilot bore
➁ gripper unit (traction)
➂ C utterhead
➃ ➃ Rear support
➄ Muck conveyor Phot o 4.1 .4 - Sauges t unnel (Swit zerland)

IV-5
 Choosing mechanized tunnelling techniques
4 . 2 - M A C H I N ES PR O V I - sides of the tunnel. The tunnel face is not sup- 4 . 2 . 2 - O p e n -f a ce g ri p p e r s h i e l d
D I N G I M M E D I ATE P ERIP H E - ported. d’aucune façon. TB M
R A L S U P P O RT They can have two types of shield: A gripper shield TBMcorresponds to the defi-
• one-can shield, nition given in § 4.1.32 except that it is
4.2.1 - G eneral mounted inside a cylindrical shield incorpo-
• shield of two or more cans connected by
rating grippers.
Machines providing immediate peripheral articulations.
support only belong to the open- face TBM The shield provides immediate passive per-
The different configurations for peripheral-
group. ipheral support to the tunnel walls.
support TBMs are detailed below.
While they excavate they also support the AFTES data sheet: N°25 ▼

➀ C utterhead ➄ Grippers (radial thrust)

➁ Muck extraction conveyor ➅ Muck transfer conveyor
➂ Télescopic section ➆ Motor
➇ Segment erector Phot o 4 .2.2 - Main CERN t unnel
➃ Thrust ram

4 . 2 . 3 - O p e n -f a ce s e g m e n t a l type units. To advance and tunnel, the TBM's

s h i e l d TB M longitudinal thrust rams react against the
tunnel lining erected behind it by a special
An open-face segmental shield TBM is fitted erector incorporated into the TBM.
with either a full-face cutterhead or an exca-
vator arm like those of the different boom- AFTES data sheets: No. 31 - 32 - 41 - 66
▼

a C utterhead g Muck transfer conveyor

b Shield h G athering arm
c Articulation (option) i Muck hopper
d Thrust ram j Motor Phot o 4 .2 .3
e Segment erector k Tailskin articulation (option) At hens met ro
f Muck extraction conveyor l Thrust ring

IV-6
 - Choosing mechanized tunnelling techniques
4 . 2 . 4 - D o u b l e s h i e ld used at any time depends on the type of by articulations and a telescopic central unit
A double shield is a TBM with a full-face cut- ground encountered. With longitudinal which relays thrust from the gripping/thrus-
terhead and two sets of thrust rams that react thrust, segmental lining must be installed ting system used at the time to the front of the
against either the tunnel walls (radial grip- behind the machine as it advances. TBM.
pers) or the tunnel lining. The thrust method The TBM has three or more cans connected AFTES data sheets: No. 65 – 68 – 71
▼

a C utterhead g Longitudinal thrust rams

b Front can h Grippers
c Telescopic section i Tailskin articulation (option)
d Gripper unit j Segment erector
e Tailskin k Muck extraction conveyor Phot o 4 .2 .4 - Salazie wat er t ransfer project
f Main thrust rams l Muck transfer conveyor (Reunion Island)

4 . 3 - M A C H I N ES P R O V I - have what is called a cutterhead chamber at 4 . 3 . 2 - M ech a n ic a l-s u p p o rt TB M

D I N G I M M E D I ATE PERIP H E - the front, isolated from the rearward part of
the machine by a bulkhead, in which a confi- A mechanical- support TBM has a full- face
R A L A N D F R O N TA L S U P -
nement pressure is maintained in order to cutterhead which provides face support by
P O RT SI M U LT A N E O U S LY
actively support the excavation and/or constantly pushing the excavated material
balance the hydrostatic pressure of the ahead of the cutterhead against the sur-
4.3.1 - G eneral
groundwater. rounding ground.
The TBMs that provide immediate peripheral The face is excavated by a cutterhead wor-
and frontal support simultaneously belong to Muck is extracted by means of openings on
king in the chamber.
the closed- faced group. the cutterhead fitted with adjustable gates
The TBM is jacked forward by rams pushing that are controlled in real time.
They excavate and support both the tunnel off the segmental lining erected inside the
walls and the face at the same time. TBM tailskin, using an erector integrated into AFTES data sheets: No. 38 – 39 – 40 – 51 –
Except for mechanical- support TBMs, they all the machine. 58 – 64 ▼

a C utterhead g Muck transfer conveyor

b Shield h Muck hopper (with optional gate)
c Articulation (option) i C utterhead drive motor
d Thrust ram j G ated cutterhead openings
e Segment erector k Peripheral seal between cutterhead and shield
f Muck extraction conveyor l Tailskin articulation (option) Phot o 4.3 .2
RER Line D (Pa ris)

IV-7
 Choosing mechanized tunnelling techniques
4 . 3 . 3 - C o m p r e ss e d - a ir TB M Muck is extracted continuously or intermit- AFTES data sheets: No. 37 – 42 – 43 – 53 –
tently by a pressure- relief discharge system 54 – 70
A compressed-air TBM can have either a full-
face cutterhead or excavating arms like those that takes the material from the confinement
of the dif f e rent boom- type units . pressure to the ambient pressure in the tun-
Confinement is achieved by pressurizing the nel.
air in the cutting chamber. ▼

a b c d e f g

h e i j k

a Excavating arm
b Shield g Tailskin seal
c C utting chamber h Airlock to cutting chamber
d Airtight bulkhead i Segment erector
e Thrust ram j Screw conveyor (or conveyor and gate)
f Articulation (option) k Muck transfer conveyor Phot o 4 .3.3 - Compressed air TBM - Boom t ype

4 . 3 . 4 - Sl u r r y s h i e l d TB M AFTES data sheets:

No. 33 – 34 – 35 – 36 –
A slurry shield TBM has a full- face cutte-
rhead. Confinement is achieved by pressuri- 44 – 50 – 52 – 56 – 57 -
zing boring fluid inside the cutterhead cham- 60 – 62 – 63 – 69 – 76 –
ber. Circulation of the fluid in the chamber Cairo – Sydney
flushes out the muck, with a regular pressure
being maintained by directly or indirectly
controlling discharge rates.
▼
a C utterhead
b Shield
c Air bubble
d Watertight bulkhead
e Airlock to cutterhead chamber

f Tailskin articulation (option)

g Thrust ram
h Segment erector
i Tailskin seal

j C utterhead chamber
k Agitator (option)
l Slurry supply line

m Slurry return line

Phot o 4 .3 .4 - Cairo met ro

IV-8
 - Choosing mechanized tunnelling techniques
4 . 3 . 5 - E a rt h p r e ss u r e b a l a nce intermittently by a pressure- relief discharge AFTES data sheets: No. 45 – 46 - 47 – 48 –
m a ch i n e system that takes it from the confinement 49 – 55 – 59 – 61 – 72 – 73 – 74* - 77 to
pressure to the ambient pressure in the tun- 85
An earth pressure balance machine (EPBM)
nel. *TBMs also working with compressed- air
has a full-face cutterhead. Confinement is
EPBMs can also operate in open mode or confinement
achieved by pressurizing the excavated
material in the cutterhead chamber. Muck is with compressed-air confinement if specially
extracted from the chamber continuously or equipped. ▼

a C utterhead
b Shield
c C utterhead chamber
d Airtight
e Thrust ram
f Articulation (option)
g Tailskin seal
h Airlock to cutterheau chamber
i Segment erector
j Screw conveyor
k Muck transfer conveyor
Phot o 4.3 .5 - CaluireTunnel, Lyons (France)

4 . 3 . 6 - M i x e d -f a ce s h i e l d TB M mode, with a belt conveyor extracting the TBMs of this type are generally restricted to
muck, and, after a change in configuration, large- diameter bores because of the space
Mixed- face shield TBMs have full- face cutte- in closed mode, with earth pressure balance required for the special equipment required
rheads and can work in closed or open mode confinement provided by a screw conveyor; for each confinement method.
and with different confinement techniques.
• Machines capable of working in open AFTES data sheets: A86 Ouest (Socatop),
Changeover from one work mode to another mode, with a belt conveyor extracting the Madrid metro packages 2 & 4, KCR 320
requires mechanical intervention to change muck, and, after a change in configuration, (Hong Kong)
the machine configuration. in closed mode, with slurry confinement pro-
Different means of muck extraction are used vided by means of a hydraulic mucking out
for each work mode. system (after isolation of the belt conveyor);
There are three main categories of machine: •Machines capable of providing earth pres-
• Machines capable of working in open sure balance and slurry confinement.

Phot o 4 .3.6a Phot o 4.3 .6 b - A86 Ouest t unnel ( Socat op)

A8 6 Oues t unnel ( Socat op) Madrid met ro

IV-9
 Choosing mechanized tunnelling techniques
5 - E V A LU A TI O N O F P A R A- • to enable project designers envisaging a each of the elementary selection parameters
mechanized tunnelling solution to check that affects each individual mechanized tunnel-
M ETERS F O R C H O ICE O F
all the factors affecting the choice have been ling technique.
M EC H A N I Z ED TU N N ELLI N G examined.
These evaluation tables are complemented
TEC H N I Q U ES • to enable contractors taking on construc- by comments in the appendix.
tion of a project for which mechanized tun-
The list of parameters is based on that drawn
5 . 1 . G E N ER A L nelling is envisaged to check that they are in
possession of all the relevant information in up by AFTES recommendations work group
order to validate the solution chosen. No. 7 in its very useful document "Choix des
It was felt useful to assess the degree to which
paramètres et essais géotechniques utiles à
elementary parameters of all kinds affect the This evaluation is presented in the form of two la conception, au dimensionnement et à
decision-making process for choosing bet- tables (Tables 1 and 2). l'exécution des ouvrages creusés en souter-
ween the different mechanized tunnelling
Table 1 (§ 5.2.) indicates the degree to which rain" (Choice of geotechnical parameters
techniques.
each of the elementary selection parameters and tests of relevance to the design and
The objectives of this evaluation are: affects each of the basic functions of mecha- construction of underground works). This ini-
• to rank the importance of the elementary nized tunnelling techniques (all techniques tial list has been complemented by factors
selection parameters, with some indication combined). other than geotechnical ones.
of the basic functions concerned. Table 2 (§ 5.3) indicates the degree to which

5 . 2 - E V A LU A TI O N O F T H E EFFECT O F ELE M E N T A R Y SELECTI O N P A R A M ETERS O N T H E

B A SIC F U N CTI O N S O F M EC H A N I Z ED TU N N ELLI N G TEC H N I Q U ES
Basic funct ion SUPPORT OPPOSITION TO MUCKING OUT,
Element ary HYDROSTATIC EXCAVATION EXTRACTION,
paramet ers Front al Peripherical PRESSURE TRANSPORT
STOCKPILING
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 1
2.2 Global appreciat ion of qualit y 2 2 0 1 0
2.3 Discont inuit ies 2 2 2 1 0
2.4 Alt erabilit y 1 1 SO 1 1
2.5 Wat er chemist ry 1 0 SO 0 1
3. MECHANICAL PARAMETERS
3.1 St rengt h Soft ground 2 2 SO 1 0
Hard rock 1 1 SO 2 0
3.2 Def ormabilit y 2 2 SO 0 0
3.3 Liquef act ion pot ent ial 0 0 0 0 0
4. HYDROGEOLOGICAL PARAMETERS 2 2 2 1 0
5. OTHER PARAMETERS
5.1 Abrasiveness - Hardness 0 0 0 2 1
5.2 Propensit y t o st ick 0 0 0 2 2
5.3 Ground/ machine f rict ion 0 1 0 0 0
5.4 Présence of gas 0 0 0 0 0
6 . PROJECT CHARACTERISTICS
6.1 Dimensions, shape 2 2 2 1 2
6 .2 Vert ical alignment 0 0 0 0 2
6 .3 Horizont al alignment 0 0 0 0 1
6 .4 Environment
6 .4 .1 Sensit ivit y t o set t lement 2 2 2 0 0
6.4 .2 Sensit ivit y t o dist urbance and work const raint s 0 0 0 0 2
6 .5 Anomalies in ground
6 .5.1 Het erogeneit y of ground in t unnel sect ion 1 1 0 2 0
6 .5.2 Nat ural/ art if icial obst acles 0 0 0 1 0
6 .5.3 Voids 2 2 2 0 0

2 : Deci si v e 1 : Has ef f ect 0 : No ef f ect SO: Not appl i cabl e

See comment s on t hi s t abl e i n A ppendi x 1

Table 1

IV-10
- Choosing mechanized tunnelling techniques

IV-11
 Choosing mechanized tunnelling techniques
6 - SPECIFIC FE A TU RES O F of machine or handled separately. It can be a series of hydraulic or electric motors. The
T H E DIFFERE N T TU N N EL - done directly from the face. tunnel can be reamed in a single pass with a
single cutterhead or in several passes with
LI N G TEC H N I Q U ES 6.1.2 - Specific features of main-beam TBMs cutterheads of increasing diameter.
a) Gener al b) Excav ation
6 . 1 - M A C H I N ES P R O V I -
The thrust at the cutterhead is reacted to one See Chapter 6.1.2 § b) (main- beam TBM).
D I N G N O I M M E D I ATE S U P -
or two rows of radial thrust pads or grippers c) Support and opposition to hydro st a
P O RT which take purchase directly on the tunnel tic pre ssu re
walls. As with shield TBMs, a trailing backup
6 . 1 . 1 - S p ecific f e a t u r e s o f b o o m - The support in the pilot bore must be des-
behind the machine carries all the equipment
t y p e t u n n e lli n g m a ch i n e s tructible (glass- fibre rockbolts) or removable
it needs to operate and the associated logis-
(steel ribs) so that the cutterhead is not dama-
tics. Forward probe drilling equipment is
a) General ged. The final support is independent of the
generally fitted to this type of TBM. The face
reaming machine, but can be erected from
Boom- type tunnelling machines are gene- can be accessed by retracting the cutterhead
its backup.
rally suited to highly cohesive soils and soft from the face when the TBM is stopped.
rock. They consist of an excavating arm or For details on opposition to the hydrostatic
The machine advances sequentially (bore, pressure, see Chapter 6.1.2 § c (main- beam
boom mounted on a self- propelling chassis.
regrip, bore again). TBM).
There is no direct relationship between the
machine and the shape of the tunnel to be b) Exca vation d) Mucking out
driven; the tunnel cross-sections excavated These full-face TBMs generally have a rotary
can be varied and variable. The face can be See Chapter 6.1.2.§ d) (main- beam TBM).
cutterhead dressed with different cutters (disc
accessed directly at all times. Since these cutters, drag bits, etc.). Muck is generally
machines react directly against the tunnel removed by a series of scrapers and a buc- 6 . 2 - S PECIFI C FE AT U RES O F
floor, the floor must have a certain bearing ket chain which delivers it onto a conveyor M A C H I N ES P R O V I D I N G
capacity. transferring it to the back of the machine. I M M E D I ATE PERIP H ER A L
b) Excav ation Water spray is generally required at the face S U P P O RT
both to keep dust down and to limit the tem-
The arms or booms of these machines are
perature rise of the cutters. 6 . 2 . 1 - S p ecific f e a t u r e s o f o p e n -
generally fitted with a cutting or milling head
which excavates the face in a series of c) Support and opposition to hydro st a - f a ce g ri p p e r s h i e l d TB M s
sweeps. These machines are called road- tic pre ssu re
headers. The maximum thrust on the road-
a) G eneral
Tunnel support is independent of the machine
header cutterhead is directly related to the (steel ribs, rockbolts, shotcrete, etc.) but can An open-face gripper shield TBM is the same
mass of the machine. The cutters work either be erected by auxiliary equipment mounted as a main-beam TBM except that it has a
transversally (perpendicular to the boom) or on the beam and/or backup. If support is cylindrical shield.
in-line (axially, about the boom axis). In most erected from the main beam, it must take The thrust of the cutterhead is reacted against
cases the spoil falling from the face is gathe- account of TBM movement and the gripper the tunnel walls by means of radial pads (or
red by a loading apron fitted to the front of advance stroke. The cutterhead is not gene- grippers) taking purchase through openings
the machine and transported to the back of rally designed to hold up the face. A canopy in the shield or immediately behind it. As with
the machine by belt conveyor. This excava- or full can is sometimes provided to protect other TBM types, a backup trailing behind
tion method generates a lot of dust which has operators from falling blocks. the TBM carries all the equipment it needs to
to be controlled (extraction, water spray, fil- operate, together with the associated logis-
tering, etc.). This kind of TBM cannot oppose hydrostatic
tics.
p re s s u re. Accompanyi ng measur e s
In some cases the cutterhead can be repla- (groundwater lowering, drainage, ground The TBM does not thrust against the tunnel
ced by a backhoe bucket, ripper, or hydrau- improvement, etc.) are required if the expec- lining or support.
lic impact breaker. ted pressures or inflows are high. b) Excav ation
c) Support and opposition to hydro st a - d) Mucking out
tic pre ssu re See Chapter 6.1.2 § b) (main-beam TBM).
Mucking out is generally done with wagons c) Support and opposition to hydro st a
There is no tunnel support associated with or by belt conveyor. It is directly linked to the tic pre ssu re
this type of machine. It must be accompanied TBM advance cycle.
by a support method consistent with the The TBM provides immediate passive per-
shape of the tunnel and the ground condi- 6.1.3. Sp e cific fe a tures of tunne l ipheral support. It also protects workers from
tions encountered (steel ribs, rockbolts, shot- reaming m achines the risk of falling blocks. If permanent tunnel
crete, etc.). support is required, it consists either of seg-
a) General ments (installed by an erector on the TBM) or
This type of machine cannot oppose hydro-
Tunnel reaming machines work in much the of support erected independently.
static pressure, so accompanying measures
(ground improvement, groundwater lowe- same way as main- beam TBMs, except that This type of machine cannot oppose hydro-
ring, etc.) may be necessary. the cutterhead is pulled rather than pushed. static pressure, so accompanying measures
This is done by a traction unit with grippers (ground improvement, groundwater lowe-
d) Mucking out in a pilot bore. As with all main-beam and ring, etc.) may be necessary when working
Mucking out can be associated with this kind shield machines, the cutterhead is rotated by in water- bearing or unstable terrain.

IV-12
 - Choosing mechanized tunnelling techniques
d) Mucking out gitudinal rams thrust against the tunnel lining gram for thrust due to water and ground at
See Chapter 6.1.2 § d) (main- beam TBM) . to shove the rear section forward. The rear the face is trapezoidal. This means there are
section regrips and the cycle is repeated. differences in the balancing of pressures at
6 . 2 . 2 - S p ecific f e a t u r e s o f o p e n - the face. The solution generally adopted
f a ce s e g m e n t a l s h i e l d TB M s 6 . 3 - S PECIFIC FE AT U RES O F involves compressing the air to balance the
water pressure at the lowest point of the face.
a) Gener al TB M S P R O V I D I N G I M M E -
The greater the diameter, the greater the
An open- face shield segmental TBM has D I ATE F R O N TA L A N D PER - resulting pressure differential; for this reason
either a full- face cutterhead or an excavating IP H ER A L S U P P O RT the use of compressed- air confinement in
arm like those of the different boom- type tun- large-diameter tunnels must be studied very
nelling machines. The TBM is thrust forward 6 . 3 . 1 - S p ecific f e a t u r e s o f m ech a - attentively.
by rams reacting longitudinally against the n ic a l-s u p p o rt s h i e l d TB M s Compressed-air TBMs are generally used
tunnel lining erected behind it. with moderate hydrostatic pressures (less
a) G ener al
b) Exca vation than 0.1 MPa).
Mechanical- support shield TBMs ensure the
TBM advance is generally sequential: stability of the excavation by retaining exca- b) Excavation
1) boring under thrust from longitudinal vated material ahead of the cutterhead. This The face can be excavated by a variety of
rams reacting against the tunnel lining is done by partially closing gates on ope- equipment (from diggers to full-face cutte-
2) retraction of thrust rams and erection of nings in the head. rheads dressed with an array of tools). In the
new ring of lining. b) Exca vation case of rotating cutterheads, the size of the
spoil discharged is controlled by the ope-
c) Support a nd opposition to hydro st a - The face is excavated by a full-face cutte- nings in the cutterheadla roue.
tic pre ssu re rhead.
Muck can be extracted from the face by a
The TBM provides passive peripheral sup- c) Support and opposition to hydro st a - screw conveyor (low hydrostatic pressure) or
port and also protects workers from the risk tic pre ssu re by an enclosed conveyor with an airlock.
of falling blocks.
Real-time adjustment of the openings in the
The tunnel face must be self-supporting. Even c) Support and opposition to hydro st a -
cutterhead holds spoil against the face. tic pre ssu re
a full-face cutterhead can only hold up the
Frontal support is achieved by holding spoil Mechanical immediate support of the tunnel
face under exceptional conditions (e.g. limi-
against the face (in front of the cutterhead). face and walls excavation is provided by the
tation of collapse when the TBM is stopped).
The shield provides immediate passive per- cutterhead and shield respectively.
Temporary or final lining is erected behind
ipheral support.
the TBM by an erector mounted on it. It is The hydrostatic pressure in the ground is
against this lining that the rams thrust to push The tunnel lining is erected: opposed by compressed air.
the machine forward. •either inside the TBM tailskin, in which case d) Mucking out
This type of machine cannot oppose hydro- it is sealed against the tailskin (tail seal) and
back grout is injected into the annular space Muck is generally removed by conveyor or
static pressure, so accompanying measures
around it, by wheeled vehicles (trains, trucks, etc.).
(ground improvement, groundwater lowe-
ring, etc.) may be necessary when working • or behind the TBM tailskin (expanded 6 . 3 . 3 - S p ecific f e a t u r e s o f sl u r r y
in water-bearing or unstable terrain. lining, segments with pea- gravel backfill and s h i e l d TB M s
d) Mucking out grout).
a) General
Muck is generally removed by mine cars or This type of machine cannot oppose hydro-
static pressure as a rule, so accompanying The principle of slurry shield TBM operation
belt conveyors. Mucking out is directly linked is that the tunnel excavation is held up by
to the TBM advance cycle. measures (ground improvement, groundwa-
ter lowering, etc.) may be necessary when means of a pressurized slurry in the cutte-
6 . 2 . 3 - S p ecific f e a t u r e s o f d o u b l e working in water- bearing or unstable ter- rhead. The slurry entrains spoil which is
s h i e l d TB M s rain. removed through the slurry return line.
d) Mucking out The tunnel lining is erected inside the TBM
Double shield TBMs combine radial pur-
tailskin where a special seal (tailskin seal)
chase by means of grippers with longitudi- Mucking out is generally by means of mine prevents leakage.
nal purchase by means of thrust rams reac- cars or belt conveyors.
ting against the lining. A telescopic section Back grout is injected behind the lining as the
at the centre of the TBM makes it possible for 6 . 3 . 2 - S p ecific f e a t u r e s o f co m - TBM advances.
excavation to continue while lining segments p r e ss e d - a ir TB M s
b) Excavation
are being erected.
a) General The face is excavated by a full-face cutte-
Excavation proceeds as follows: with the rear
With compressed- air TBMs, only pressuri- rhead dressed with an array of cutter tools.
section of the TBM secured by the grippers,
zation of the air in the cutter chamber Openings in the cutterhead (plus possibly a
the front section thrusts against it by means
opposes the hydrostatic pressure at the face. crusher upline of the first slurry return line
of the main rams between the two sections,
suction pump) control the size of spoil remo-
and tunnels forward. A ring of segmental Compressed- air confinement pressure is
ved before it reaches the pumps.
lining segments is erected at the same time. practically uniform over the full height of the
The grippers are then released and the lon- face. On the other hand, the pressure dia-

IV-13
 Choosing mechanized tunnelling techniques
c) Support and opposition to hydro st a - sure bulkhead, and the muck- extraction the biodegradability of the additives if the
tic pre ssu re screw conveyor. By reducing friction, the disposal site is in a sensitive environment.
Frontal and peripheral support of the tunnel additives reduce the torque required to churn The architecture of this type of TBM allows for
excavation are the same, i.e. by means of the the spoil, thus liberating more torque to work rapid changeover from closed to open mode
slurry pressure generated by the hydraulic on the face. They also help maintain a and vice versa.
mucking out system. constant confinement pressure at the face.
In permeable ground (K ≥ 5 x 10-5 m/s) it is Muck is extracted by a screw conveyor, pos-
possible to pressurize the chamber by crea- sibly together with other pressure- reli ef 7 - A PPLIC A TI O N O F
ting a ‘cake’ of thixotropic slurry (bentonite, devices.
M EC H A N I Z ED TU N N ELLI N G
polymer, etc.), generally with relative density The tunnel lining is erected inside the TBM TEC H N I Q U ES
of between 1.05 and 1.15, on a tunnel face tailskin, with a tailskin seal ensuring there are
and walls. no leaks. Back grout is injected behind the
With such a ‘cake’ in place it is possible for lining as the TBM advances. 7 . 1 - M A C H I N ES N O T P R O -
workers to enter the pressurized cutterhead b) Excav ation V ID I N G I M M E D I ATE S U P -
(via an airlock).
The tunnel is excavated by a full- face cutte-
P O RT
The TBM can be converted to open mode, but rhead dressed with an array of tools. The size
the task is complex. of spoil removed is controlled by openings in 7 . 1 . 1 - B o o m -t y p e t u n n e lli n g
the cutterhead which are in turn determined m a ch i n e s
As for tunnel support, the hydrostatic pres-
sure is withstood by forming a ‘cake’ to help by the dimensional capacity of the screw Boom- type units are generally suitable for
form a hydraulic gradient between the conveyor.
highly cohesive soils and soft rock. They
hydrostatic pressure in the ground and the The power at the cutterhead has to be high reach their limits in soils with compressive
slurry pressure in the cutterhead chamber. because spoil is constantly churned in the strength in excess of 30 to 40 MPa, which
Together with control of the stability of the cutterhead chamber. corresponds to class R3 to R5 in the classifi-
excavation and of settlement, opposition to c) Support and opposition to hydro st a - cation given in Appendix 3 (depending on
hydrostatic pressure is a design considera- tic pre ssu re the degree of cracking or foliation). The
tion for the confinement pressure; the confi- effective power of these machines is directly
Face support is uniform. It is obtained by related to their weight.
nement pressure is regulated either by direct
means of the excavated spoil and additives
adjustment of the slurry supply and return When these machines are used in water-
which generally maintain its relative density
pumps or by means of an “air bubble” whose bearing ground, some form of ground
at between 1 and 2. Peripheral support can
level and pressure are controlled by a com- improvement must be carried out before-
be enhanced by injecting products through
pressor and relief valves. With an “air hand to overcome the problem of significant
the shield.
bubble” in the cutterhead chamber the confi- water inflow.
nement pressure can be measured and regu- For manual work to proceed in the cutte-
lated within a very narrow range of varia- rhead chamber, it may be necessary to When excavating clayey soils in water, the
tion. create a sealing cake at the face through cutters of roadheaders may become clogged
controlled substitution (without loss of confi- or balled; in such terrain, a special study of
d) Mucking out the cutters must carried out to overcome the
nement pressure) of the spoil in the chamber
Muck is removed by pumping it through the with bentonite slurry. problem. It may be advisable to use a back-
pipes connecting the TBM to the slurry sepa- hoe instead.
L’architecture de ce type de tunnelier permet
ration and recycling plant. These techniques are particularly suitable for
un passage rapide du mode fermé en mode
In most cases the muck is often treated out- ouvert. excavating tunnels with short lengths of dif-
side the tunnel, in a slurry separation plant. ferent cross- sections, or where the tunnel is
The hydrostatic pressure is withstood by for- to be driven in successive headings.
This does introduce some risks associated
ming a plug of confined earth in the cham-
with the type of spoil to be treated (clogging The tunnel support accompanying this
ber and screw conveyor; the pressure gra-
of plant, difficulties for disposal of residual method of excavation is independent of the
dient between the face and the spoil
sludge). machine used. It will be adapted to the condi-
di scharge point is balanced by pressure
The pump flowrate and the treatment capa- losses in the extraction and pressure- relief tions encountered (ground, environment,
city of the separation plant determine TBM device. etc.) and the shape of the excavation.
progress.
Care must be take over the type and location 7 . 1 . 2 - M a i n - b e a m TB M s
6 . 3 . 4 - S p ecific f e a t u r e s o f e a rt h of sensors in order to achieve proper mea-
p r e ss u r e b a l a nce m a ch i n e s surement and control of the pressure in the Main-beam TBMs are particularly suited to
cutterhead chamber. tunnels of constant cross-section in rock of
a) General strength classes R1 to R4 (see rock classifi-
d) Mucking out cation in Appendix 3).
The principle of EPBM operation is that the
excavation is held up by pressurizing the After the muck-extraction screw conveyor, For the lower strength classes (R3b- R4), the
spoil held in the cutterhead chamber to spoil is generally transported by conveyors bearing surface of the grippers is generally
balance the earth pressure exerted. If neces- or by wheeled vehicles (trains, trucks). increased in order to prevent them punching
sary, the bulked spoil can be made more The muck is generally “diggable”, enabling into the ground. If there is a risk of alteration
plastic by injecting additives from the ope- it to be disposed of without additional treat- of the tunnel floor due to water, laying a
nings in the cutterhead chamber, the pres- ment; however, it may be necessary to study concrete invert behind the machine will faci-

IV-14
 - Choosing mechanized tunnelling techniques
litate movement of the backup. To provide 7 . 2 - M A C H I N ES PR O VI - 7 . 3 - M A C H I N ES P R O V I -
short- term stabilization of the excavation, it D I N G I M M E D I ATE PERIP H E - D I N G I M M E D I ATE F R O N TA L
will be necessary to have rapid support- erec- R A L S U P P O RT A N D PERIP H ER A L S U P P O RT
tion systems that will be independent of but
nevertheless compatible with the TBM. 7 . 2 . 1 - O p e n -f a ce g ri p p e r s h i e l d 7 . 3 . 1 - M ech a n ic a l-s u p p o rt s h i e l d
TB M s TB M s
For the higher strength classes (R1- R2a), all
the boreability parameters must be taken into Open-face gripper shield TBMs are particu- The difference between mechanical- support
account in the TBM design. larly suitable for tunnelling in rock of strength shield TBMs and open-face segmental shield
classes between R1 and R3 TBMs lies in the nature of the cutterhead.
In hard and abrasive ground in particular, it Mechanical- support TBMs have:
is recommended that every precaution be The shield provides immediate support for
• openings with adjustable gates
taken to allow for cutters to be replaced in the tunnel and/or protects the workforce
perfect safety. from falling blocks. • a peripheral seal between the cutterhead
and the shield.
A system for spraying water on the tunnel The shield can help get through certain geo-
logical difficulties by avoiding the need for Face support is achieved by holding spoil
face will cool the cutters and keep dust down. ahead of the cutterhead by adjusting the
support immediately behind the cutterhead.
It can be complemented by dust screens, openings. It does not provide ‘genuine’
extraction, and filters. Application of this technique can be limited confinement, merely passive support of the
by the ability of the ground to withstand the face.
Main- beam TBMs are generally fitted with radial gripper thrust.
destructive drilling rigs for forward probe Its specific field of application is therefore in
The general considerations outlined in § soft rock and consolidated soft ground with
drilling, together with drill data- logging
7.1.2 also apply here. little or no water pressure
equipment. The probe holes are drilled when
the TBM is not working. 7 . 2 . 2 - O p e n -f a ce s e g m e n t a l 7 . 3 . 2 - C o m p r e ss e d - a ir TB M s
The design of these machines does not allow s h i e l d TB M s
Compressed- air TBMs are particularly sui-
them to support non- cohesive soils as they An open- face segmental shield TBM requires table for ground of low permeability with no
advance, or to oppose hydrostatic pressure. full lining or support along the length of the major discontinuities (i.e. no risk of sudden
For this reason accompanying measures tunnel against which it can thrust to advance. loss of air pressure).
such as drainage and/or consolidation of Its field of application is soft rock (strength The ground tunnelled must necessarily have
the ground are necessary before the classes R4 and R5) and soft ground requiring an impermeable layer in the overburden.
machines traverse a geological accident. support but in which the tunnel face holds up. Compressed- air TBMs tend to be used to
Consequently the TBM must be equipped to The general considerations outlined in § excavate small-diameter tunnels.
detect such features and to treat the ground 7.1.2 also apply here. Their use is not recommended in circum-
ahead of the face when necessary. stances where the ground at the face is hete-
This type of TBM can traverse certain types
of heterogeneity in the ground. It also rogeneous (unstable ground in the roof
7 . 1 . 3 - Tu n n e l r e a m i n g m a ch i n e s which could cave in). They should be prohi-
enables the tunnel support to be industriali-
bited in organic soil where there is a risk of
Tunnel reamers are suitable for excavating zed to some extent. On the other hand, the
fire.
large horizontal or inclined tunnels (upwards presence of the lining and shield can give rise
to difficulties when crossing obstacles such In the case of small- diameter tunnels, it may
of 8 m in diameter) in rock (R1 to R3, some-
as geological accidents, since they hinder be possible to have compressed air in all or
times R4 and R5). part of the finished tunnel.
access to the face for treatment or consoli-
The advantages of reaming a tunnel from a dation of the ground. 7 . 3 . 3 - Sl u r r y s h i e l d TB M s
pilot bore are as follows:
7 . 2 . 3 - O p e n -f a ce d o u b l e s h i e l d Slurry shield TBMs are particularly suitable
• The ground is investigated as the pilot bore TB M s for use in granular soil (sand, gravel, etc.)
is driven
and heterogeneous soft ground, though they
Open-face double shield TBMs combine the
• Any low-strength ground encountered can can also be used in other terrain, even if it
advantages and disadvantages associated
be consolidated from the pilot bore before includes hard- rock sections.
with radial grippers and longitudinal thrust
full- diameter excavation rams pushing off tunnel lining: they need There might be clogging and difficulty sepa-
either a lining or ground of sufficient strength rating the spoil from the slurry if there is clay
• The ground to be excavated is drained
to withstand gripper thrust. in the soil.
• The pilot bore can be used for dewatering These TBMs can be used in ground with high
and ventilation This greater technical complexity is some-
times chosen when lining is required so that permeability (up to 10-2 m/s), but if there is
• Temporary support can be erected inde- high water pressure a special slurry has to
boring can proceed (with gripper purchase)
be used to form a watertight cake on the
pendently of the machine. while the lining ring is being erected.
excavation walls. However, their use is
usually restricted to hydrostatic pressures of
a few dozen MPa.

IV-15
 Choosing mechanized tunnelling techniques
Generally speaking, good control of slurry lement- especially in built- up areas- should period to proceed with tests of the tunnelling
quality and of the regularity of confinement be given special attention. This is a decisive and support methods as well as any asso-
pressure ensures that surface settlement is factor in choosing the tunnelling and support ciated treatments.
kept to the very minimum. methods, the tunnel alignment, and the
If there are to be forward probe investiga-
Contaminated ground (or highly aggressive cross- section.
tions, matching of the boring and investiga-
water) may cause problems and require spe- The environmental impact assessment should tion methods should be envisaged at the pre-
cial adaptation of the slurry mix design. be thorough, taking account of the density of liminary investigation stage.
The presence of methane in the ground is not existing works and the diversity of their beha-
viours. In the event of exceptional overburden condi-
a problem for this kind of TBM. tions and difficult access from the surface,
If the tunnel alignment runs through contras- For existing underground works, the com- di rectional drilling investigation (mining
ting heterogeneous ground, there may be patibility of the proposed tunnelling and sup- and/or petroleum industry techniques) of
difficulties extracting and processing the port methods or the adaptations required long distances (one kilometre or more) along
spoil. (special treatment or accompanying mea- the tunnel alignment may be justified, espe-
sures) should be assessed through special cially if it is associated with geophysical
7 . 3 . 4 - E a rt h p r e ss u r e b a l a nce analysis.
investigations and appropriate in situ tes-
m a ch i n e s ting.
8 . 1 . 2 - G r o u n d co n d iti o n s
EPBMs are particularly suitable for soils
which, after churning, are likely to be of a The purpose of preliminary investigations is
not just for design of the temporary and per-
8 . 2 - F O R W A RD PR O BI N G
consistency capable of transmitting the pres-
sure in the cutterhead chamber and forming manent works, but also to check the feasibi-
The concept of forward probing must be set
a plug in the muck- extraction screw conveyor lity of the project in constructional terms, i.e.
against the risk involved. This type of inves-
(clayey soil, silt, fine clayey sand, soft chalk, with respect to excavation, mucking out, and
tigation is cumbersome and costly, for it
marl, clayey schist). short- and long- term stability.
penalizes tunnelling progress since— in the
They can handle ground of quite high per- Design of the works involves determining case of full- face and shield TBMs— the
meability (10–3 to 10-4 m/s), and are also shape, geological cross-sections, the physi- machine has to be stopped during probing
capable of working in ground with occasio- cal and mechanical characteristics of the (with current- day technology). It should the-
nal discontinuities requiring localized confi- ground encountered by the tunnel, and the refore be used only in response to an expli-
nement.en l’absence hydrogeological context of the project as a cit and absolute requirement to raise any
whole. uncertainty over the conditions to be expec-
In hard and abrasive ground it may be
necessary to use additives or to take special Project feasibility is determined by the poten- ted when crossing areas where site safety,
measures such as installing hard-facing or tial reactions of the ground, including details preservation of existing works, or the dura-
wearplates on the cutterhead and screw of both the formations traversed and of the bility of the project might be at risk.
conveyor.a vitesse de progression de l’usure terrain as a whole, with respect to the loa-
Irrespective of the methodology selected, it
par dings generated by the works, i.e. with res-
must give the specialists implementing it real
pect to the excavation/confinement method
In permeable ground, maintenance in the adopted. possibilities for avoiding difficulties by
c u t t erhead chamber is made complex implementing corrective action in good time.
because of the need to establish a watertight Depending on the context and the specific
requirements of the project, the synopsis of The first condition that forward probing must
cake at the face beforehand, without losing meet in order to achieve this objective is that
confinement pressure. investigation results should therefore deal
with each of the topics detailed in the AFTES it give sufficiently clear and objective infor-
recommendations on the choice of geotech- mation about the situation ahead of the face
nical tests and parameters, irrespective of the (between 1 and 5 times the tunnel diameter
8 - TEC H N I Q U ES A CC O M PA - geological context (cf.: T.O.S No. 28, 1978, ahead), with a leadtime consistent with the
N YI N G M EC H A N I Z ED TU N - re- issued 05/93 – review in progress; and rate of tunnel progress.
N ELLI N G T.O.S No. 123, 1994). The second condition is that in terms of qua-
If the excavation/confinement method is lity it must be adapted to the specific requi-
8 . 1 - P RELI M I N A R Y I N V E S - only chosen at the tender stage, and depen- rements of the project (identification of clear
T I G ATI O N S F R O M T H E S U R - ding on the confinement method chosen by voids, of decompressed areas, faults, etc.).
the Contractor, additional investigations These criteria should be determined jointly
FA CE may have to be carried out to validate the by the Designer, Engineer, and Contractor
various options adopted. and should be clearly featured in specifica-
8 . 1 . 1 - En v ir o n m e n t a l i m p a ct tions issued to the persons carrying out the
a ss e ss m e n t 8 . 1 . 3 - R e s o u rce s u s e d investigations.
At the preliminary design stage an environ- Depending on the magnitude and com- During tunnelling, analysis of results is gene-
mental impact assessment should be carried plexity of the project, preliminary investiga- rally the responsibility of the investigations
out in order to properly assess the dimensio- tions - traditionally based on boreholes and contractor, but the interpretation of data, in
nal characteristics proposed for the tunnel, borehole tests - may be extended to “large- correlation with TBM advance parameters
particularly its cross-section, sectional area, scale” observation of the behaviour of the (monitoring), should in principle be the res-
and overburden. ground by means of test adits and shafts. ponsibility of the contractor operating the
In addition, the effect and sensitivity of sett- Advantage can be taken of the investigation TBM.

IV-16
 - Choosing mechanized tunnelling techniques
8 . 3 - G R O U N D I M PR O V E - 8 . 4 - G U I D A N CE (bentonite), with hydrosoluble polymers, or
MENT with surfactants to form a conditioning fluid
Guidance of full-face TBMs is vital. The per- (slurry or foam).
Prior ground improvement is sometimes formance of the guidance system used must
c) Air
be consistent with the type of TBM and lining,
necessary, particularly in order to cross: By itself air cannot be considered to be a
and with the purpose of the tunnel.
•singular features such as break- ins and boring additive in the same way as water or
The development of shield TBMs incorpora- other products; its conditioning action is very
breakouts, including on works along the ting simultaneous erection of precast seg-
route (shafts, stations, etc.) limited. When used in pressurized TBMs - if
mental lining has led to the design of highly the permeability of the ground does not pro-
•discontinuities and fault zones identified sophisticated guidance systems, because hibit it - air helps support the tunnel. As a
beforehand with tunnel lining it is impossible to remedy compressible fluid, air helps damp confine-
devi ati on f rom the cor r ect cour se. ment- pressure variations in the techniques
•permeable water- bearing ground.
Consequently, the operator (or automatic using slurry machines with “air bubbles” and
If the problem areas are of limited extent, operating system) must be given real- time EPB machines with foam. As a constituent of
ground improvement will sometimes enable information on the position of the face and foam, air also helps fluidify and reduce the
a less sophisticated - and therefore less costly the tunnelling trend relative to the theoretical density of muck, and helps regulate the confi-
- tunnelling technique to be adopted. alignment. However, when considering the nement pressure in the earth - pres s ure-
construction tolerance it must be remembe- balance process.
Since ground improvement is long and costly red that the lining will not necessarily be cen-
to carry out from the tunnel (especially when tred in the excavation, and that it may be sub- d) Bentonite
the alignment is below the water table), the ject to i ts own defor mation (off s e t , Of the many kinds of clay, bentonite is most
work is generally done from the surface (in ovalization, etc.). The generally accepted certainly the best-known drilling or boring
the case of shallow overburden). tolerance is an envelope forming a circle mud. It has extremely high swell, due to the
about 20 cm larger in diameter than the theo- presence of its specific clayey constituent,
These days, however, there is a trend for retical diameter. montmorillonite, which gives it very interes-
TBMs to be fitted with the basic equipment Whatever the degree of sophistication of the ting colloidal and sealing qualities.
(such as penetrations in the bulkhead and/or guidance system, it is necessary to: In the slurry- confinement technique, the
cans) enabling ground improvement to be rheological qualities of bentonite (thixo-
• reliably transfer a traverse into the tunnel
carried out from the machine should water- and close it as soon as possible (breakout tropy) make it possible to establish a confi-
bearing ground not compatible with the tun- into shaft, station, etc.) nement pressure in a permeable medium by
nelling technique adopted be encountered sealing the walls of the excavation through
• carry out regular and precise topographi- pressurized filtration of the slurry into the soil
unexpectedly. This can also be the case when
cal checks of the position of the TBM and of (formation of a sealing cake through a com-
local conditions prohibit treatment from the the tunnel bination of permeation and membrane), and
surface.
• know how quickly (speed and distance) the to transport muck by pumping.
When confinement- type TBMs are used, TBM can react to modifications to the trajec- Bentonite slurry can also be used with an EPB
geological and hydrogeological conditions tory it is on. machine, to improve the consistency of the
often require special treatment for break- ins granular material excavated (homogeniza-
and breakouts. This point should not be over- 8 . 5 - A D D ITI V E S tion, plastification, lubrication, etc.).
looked, neither at the preliminary design In permeable ground, the EPB technique uses
stage (surface occupation, ground and net- a) Genera l the same principle of cake formation before
work investigations, works schedule) nor Mechanized tunnelling techniques make use work is carried out in the pressurized cutte-
during the construction phase, for this is one of products of widely differing physical and rhead chamber.
of the most difficult phases of tunnelling. chemical natures that can all be labelled e) Polymers
“conditioning fluids and slurries”. Before any
Special attention should be given to the com- Of the multitude of products on the market,
chemical additives are used, it should be
patibility of ground treatment with the tun- checked that they present no danger for the only hydrosoluble or dispersible compounds
nelling process (foaming, reaction with environment (they will be mixed in with the are of any interest as tunnelling additives.
slurry and additives, etc.) muck and could present problems when it is Most of these are well known products in the
disposed of) or for the workforce (particu- drilling industry whose rheological proper-
The most commonly used ground improve- ties have been enhanced to meet the specific
larly during pressurized work in the cutte-
ment techniques are: requirements of mechanized tunnelling.
rhead chamber where the temperature can
• permeati on- grouted plug of bentonite- be high). These modifications essentially concern
cement and/or gel b) Wa t e r enhanced viscosifying power in order to bet-
• diaphragm-wall box ter homogenize coarse granular materials,
Wat er w i l l be pr esent i n t he gr ound i n and enhanced lubrifying qualities in order to
• total replacement of soil by bentonite- varying quantities, and will determine the limit sticking or clogging of the cutterhead
cement soil's consistency, as can be seen from diffe- and mucking out system when boring in cer-
rent geotechnical characterization tests or tain types of soil.
• jet- grouted plug
concrete tests (Atterberg limits for clayey
soils and slump or Abrams cone test for gra- Polymers may be of three types:
nular soils). It can be used alone, with clay • natural polymers (starch, guar gum, xan-

IV-17
 Choosing mechanized tunnelling techniques
than gum, etc.) Without any transition and in perfectly either pea gravel or fast-setting or fast- har-
• modified natural or semi-synthetic poly- controlled fashion, the lining and backgrout dening cement slurry or mortar that was
mers (CMC [carboxymethylcellulose], etc.) must balance the hydrostatic pressure, sup- injected intermittently through holes in the
port the excavation peripherally, and limit segments.
• synthetic polymers (polyacrylami des, surface settlement.
polyacrylates, etc.) Since management of the grout and its har-
Because of their interfaces with the machine, dening between mixing and injection is a
f) Fo ams (surf a ct a nts) they must be designed in parallel and in very complex task, there has been a constant
Foams are two-phase systems (a gas phase interdependence with the TBM. trend to drop cement- based products in
and a liquid phase containing the foaming favour of products with retarded set (pozzo-
8 . 7 . 2 - Li n i n g lanic reaction) and low compres s i v e
agent) which are characterized physically by
their expansion factor (volume occupied by The lining behind a shield TBM generally strength. Such products are injected conti-
the air in the foam relative to the volume of consists of reinforced concrete segments. nuously and directly into the annular space
liquid). Sometimes (for small- diameter tunnels) cast- directly behind the TBM tailskin by means of
iron segments are used. More exceptionally grout pipes routed through the tailskin.
Foams are easy to use. They are similar to
aerated slurries, combining the advantages the lining is slipcast behind a sliding form.
of a gas (compressibility, practically zero Reinforced concrete segments are by far the
density, etc.) and of a slurry (fluidification,
9 - H E A LT H A N D S A FETY
most commonly used. The other techniques
lubrication, pore filling, etc.). With EPB are gradually being phased out for econo- Mechanization of tunnelling has very sub-
machines they are used to facilitate confine- mic or technical reasons. stantially improved the health and safety
ment and sometimes excavation and muc- The segments are erected by a machine conditions of tunnellers. However, it has also
king out as well. incorporated into the TBM which grips them induced or magnified certain specific risks
either mechanically or by means of suction. that should not be overlooked. These include:
8 . 6 - D ATA L O G G I N G The following AFTES recommendations exa- • risk of electrical fire or spread of fire to
mine tunnel lining: hydraulic oils
The acquisition and restitution of TBM ope- • risk of electrocution
rating parameters is undoubtedly the biggest • Recommandations sur les revêtements
factor in the technical progress of mechani- préfabriqués des tunnels circulaires au tun- • risks during or subsequent to compressed-
zed tunnelling in the last ten years. nelier (Recommendations on precast lining air work
of bored circular tunnels), TOS No. 86 • risks inherent to handling of heavy parts
It makes for objective analysis of the opera-
• Recommandation sur les joints d’étan- (lining segments)
ting status and dysfunctions of the machine
and its auxiliaries. chéité entre voussoirs (Recommendations on • mechanical risks
gaskets between lining segments), TOS No. • risk of falls and slips (walkways, ladders,
The status of the machine at any given time 116, March/April 1993
is short-lived and changes rapidly. Without etc.)
data logging, this gave rise to varied and • Recommandations “pour la conception et
often erroneous interpretations in the past. le dimensionnement des revêtements en 9 . 1 - D E SI G N O F TU N N EL -
voussoirs préfabriqués en béton armé instal-
Logging gives a “true” technical analysis that LI N G M A C H I N ES
lés à l’ar r i è re d’un tun neli er”
is indispensable for smooth operation on (Recommendations “on the design of precast
projects in difficult or sensitive sites. Tunnelling machines are work items that must
reinforced concrete lining segments installed comply with the regulations of the Machinery
Data logging also provides a basis for com- behind TBMs”) drawn up by AFTES work
Directive of the European Committee for
puterized control of TBM operation and group No. 18, published in TOS No. 147,
Standardization (CEN).
automation of its functions (guidance, muc- May/June 1998.
king out, confinement pressure regulation, These regulations are aimed primarily at
etc.). 8 . 7 . 3 - B a c k g r o u ti n g designers— with a view to obtaining equip-
ment compliant with the Directive— but also
Data logging also provides an exact record This section concerns only mechanized tun-
at users.
of operating statuses and their durations (cf. nelling techniques involving segmental
recommendation on analysis of TBM opera- lining. The standards give the minimum safety mea-
ting time and coefficients, TOS No. 148, July sures and requirements for the specific risks
Experience shows the extreme importance of
98). associated with the different kinds of tunnel-
controlling the grouting pressure and filling
ling machines. Primarily they apply to
They also constitute operating feedback that of the annular space in order to control and
restrict settlement at the surface and to secu- machines manufactured after the date of
can be used to optimize TBM use. approval of the European standard.
rely block the lining ring in position, given
that in the short term the lining is subject to • At the time of writing only one standard
8 . 7 - T U N N EL LI N I N G A N D its selfweight, TBM thrust, and possibly flota- had been homologated:
B A C K G R O U TI N G tional forces. - NF EN 815 “Safety of unshielded tunnel
Grouting should be carried out continuously, boring machines and rodless shaft boring
8.7.1 - G eneral with constant control, as the machine machines for rock” (December 1996)
In t he case of segment al TBMs, t he advances, before a gap appears behind the • Three are in the approval process:
lining and its backgrouting are inseparable TBM tailskin. - Pr EN 12111 “Tunnelling machines -
from the operation of the machine. In the early days backfilling consisted of Roadheaders, continuous miners and impact

IV-18
 Choosing mechanized tunnelling techniques
rippers – Safety requirements”
- Pr EN 12336 “Tunnelling machines –
Shield machines, horizontal thrust boring
machines, lining erection equipment - Safety
requirements ”
- Pr EN 12110 “Tunnelling machines –
Airlocks – Safety requirements ”

9 . 2 - U SE O F T U N N ELLI N G
M A C H I N ES
Machine excavation of underground works
involves specific risks linked essentially to
atmospheric pollution (gas, toxic gases,
noise, temperature), flammable gases and
other flammable products in the ground,
electrical equipment (low and high voltage),
hydraulic equipment (power or control
devices), and compressed- air work (work in
large-diameter cutterhead chambers under
compressed air, pressurization of whole sec-
tions of small-diameter tunnels).
A variety of bodies dealing with safety on
public works projects have drawn up texts
and recommendations on safety. In France,
these include OPPBTP, CRAM, and INRS, for
example.
All their requirements should be incorpora-
ted into the General Co- Ordination Plan and
Health and Safety Plan at the start of works.

A PPE N DICES 1 , 2 , 3 , A N D 4
1. Comments on Table No. 1 in Chapter 5
2. Comments on Table No. 2 in Chapter 5
3. Ground classification table
4. Mechanized tunnelling project data
sheets

IV-19
 Choosing mechanized tunnelling techniques
APPENDI X 1

C O M M E N TS O N T A BLE N O . 2 . 2 - G l o b a l a p p r e ci a ti o n t he ar chi t ect ur e of t he machi ne and

1 I N C H A PTER 5 . o f q u a lit y hel ps det er mi ne i t s t echni cal char ac-
t er i st i cs ( t or que, pow er , et c.) and
❑ Suppor t ( col umns A and B) t he choi ce of cut t i ng t ool s.
1 - N a t u r a l c o n s t r a i n ts
Gl obal appr eci at i on of qual i t y pr o-
3 . 2 - D e f o r m a b ilit y
Su p p o rt (columns A and B) v i des addi t i onal i nf or mat i on f or i den-
t i f i c at i on t hat c onc er ns onl y t he
With knowledge of natural constra ints: ❑ Suppor t ( col umns A and B)
sampl e. Thi s dat a def i nes mor e gl obal
• a choi ce can be made f r om among t he i nf or mat i on at t he scal e of t he soi l Wi t h know l edge of def or mabi l i t y t he
t unnel l i ng t ec hni que gr oups ( f r om hor i zon concer ned. r el ax at i on of st r esses can be asses-
boom- t y pe uni t s t o conf i nement - t y pe s ed and t ak en i nt o ac c ount ( f r om
2 . 3 - D isc o n ti n u it i e s si mpl e def or mat i on or conv er gence t o
TBMs)
f ai l ur e) .
• r el ax at i on of st r esses can be mana-
❑ Suppor t ( col umns A and B)
g e d ( f r o m s i m pl e de f or m a t i o n -
Thi s dat a concer ns r ock and coher ent 3 . 3 - Li q u e f a ct i o n p o t e n t i a l
conv er gence t o f ai l ur e) .
sof t gr ound. Wi t h know l edge of di s- ❑ Suppor t and mucki ng out ( col umns
cont i nui t i es a c hoi c e c an be m ade A , B and E)
2 - P H Y SIC A L P A R A M ETERS among t he t unnel t echni que gr oups
( f r om boom- t y pe uni t s t o conf i ne- Know l edge of t he l i quef act i on pot en-
ment - t y pe TBMs) . t i al has an ef f ect i n sei smi c zones and
2 . 1 - I d e n t if ic a t i o n i n cases w her e t he t echni que chosen
❑ Opposi t i on t o hy dr ost at i c pr essur e mi ght set up v i br at i ons i n t he gr ound
❑ Face suppor t ( col umn A ) ( col umn C) ( bl ast i ng, et c.) .
Wi t h know l edge of phy si cal par ame- Wi t h know l edge of di scont i nui t i es t he
t er s: cr ack per meabi l i t y and w at er pr es-
sur e t o be t aken i nt o account f or t he 4 - H Y DR O G E O L O G IC A L
• t he suppor t met hod can be assessed, pr oj ect can be assessed. Thi s enabl es PA R A M ETERS
and t he t unnel l i ng t ec hni que gr oup t he t y pe of t echni que t o be chosen.
chosen ❑ Suppor t , opposi t i on t o hy dr ost at i c
❑ Ex cav at i on ( col umn D) pr essur e, and ex cav at i on ( Col umns
• t he r equi r ement f or f ace suppor t A , B, C and D)
can be assessed. In conj unct i on w i t h know l edge of bl ock
si zes, know l edge of di scont i nui t i es Know l edge of t hese par amet er s i s
❑ Per i pher al suppor t ( col umn B) ( nat ur e, si ze, and f r equency ) can be deci si v e i n appr eci at i ng cont r ol of t he
Wi t h know l edge of phy si cal par ame- deci si v e or mer el y hav e an ef f ect on st abi l i t y of t he t unnel , bot h at t he f ace
t er s t he r equi r ement f or per i pher al t he ex cav at i on met hod t o be adopt ed. and per i pher al l y , and t her ef or e i n
suppor t ar ound t he machi ne can be choosi ng t he met hod f r om t he v ar i ous
t unnel l i ng t echni ques. In t he case of
assessed. 3 - M EC H A N IC A L P A R A M E- t unnel s beneat h deep ov er bur den i t i s
❑ Opposi t i on t o hy dr ost at i c pr essur e TERS not easy t o obt ai n t hese par amet er s.
( col umn C) They shoul d be est i mat ed w i t h t he
gr eat est car e and anal y zed w i t h cau-
Wi t h know l edge of phy si cal par ame- 3 . 1 - St r e n g t h t i on.
t er s and of gr ai n and bl ock si zes, t he
per meabi l i t y of t he t er r ai n can be ❑ Suppor t ( col umns A and B)
assessed, l eadi ng t o a pr oposal f or t he Wi t h know l edge of mechani cal par a- 5 - O T H ER P A R A M ETERS
w ay hy dr ost at i c pr essur e coul d be met er s a pr el i mi nar y choi ce can be
cont r ol l ed. made f r om among t he t unnel l i ng t ech- ❑ Ex c a v a t i o n a n d m u c k i n g o u t
ni que gr oups ( f r om boom- t y pe uni t s ( Col umns D and E)
❑ Ex cav at i on ( col umn D)
t o conf i nement - t y pe TBMs) . The par amet er s of abr asi v eness and
Of t he par amet er s concer ned, gr ai n har dness ar e deci si v e or hav e an
and bl ock si ze ar e deci si v e f or asses- ❑ Ex cav at i on ( har d r ock) ( col umn D) ef f ect i n appr eci at i on of t he ex cav a-
si ng t he ex cav at i on met hod ( desi gn of Know l edge of mechani cal par amet er s t i on and mucki ng- out met hods t o be
cut t er head, cut t er s, et c.) . i s par t i cul ar l y i mpor t ant f or def i ni ng us ed. Thes e par amet er s shoul d be

IV-20
 Choosing mechanized tunnelling techniques
APPENDI X 2

Co m m e nts o n Ta ble N o . 1 in cient st r engt h f or gr ipper s, conf inement 2 .5 - W a ter ch e m istr y

Ch a pte r 5 dif f icult ies.
The degr ee of w eat her ing of r ock has an Pr oblems r elat ed t o t he aggr essiv it y or
t he degr ee of pollut ion of w at er may
ef f ect but is not gener ally decisiv e f or
ar ise in v er y specif ic cases and hav e t o
slur r y shields and EPBMs. In all cases it
1 - N ATUR AL C O N STRA I N TS has an ef f ect f or cut t er head design.
be dealt w it h r egar dless of t he t unnelling
pr inciples adopt ed.
The st r ess pat t er n in t he gr ound is v er y
impor t ant in deep t unnels or in cases of Wit h conf inement - t y pe TBMs t his par a-
2.3 - Disco ntin uities met er may be decisiv e because of it s
hi gh anisot r opy . If t he r at e of st r ess
r elease is high, w it h main- beam TBMs, ef f ect on t he qualit y of t he slur r y or
For r ock, know ledge of t he si t uat ion addit iv es.
shield TBMs, and r eaming machines, it r egar di ng di scont i nui t i es i s deci si v e
may cause: (or ient at ion and densit y of t he net w or k),
• j amming of t he machine (j amming of f or it w ill af f ect t he choice of t he t un-
t he cut t er head or body ) nelling and suppor t t echnique as w ell as
3 - MEC H A N IC AL PA R A M E-
t he t unnelling speed. TE R S
• r ockbur st at t he f ace or in t unnel w alls,
r oof , or inv er t . Wi t h open- f ace mai n- beam TBMs and
Wit h slur r y - shield TBMs or EPBMs it is shields and mechanical- suppor t TBMs, 3 . 1 - Stre n g t h
r ar e f or t he nat ur al st r ess pat t er n t o be at t ent ion should be giv en t o t he r isk of
j amming of t he machine induced by t he In t he case of r ock, t he essent ial mecha-
decisiv e in t he choice of machine t y pe
densit y of a net w or k of discont inuit ies nical cr it er ia ar e t he compr essiv e and
since t hey ar e gener ally used f or shal-
w hich could quit e r apidly lead t o doubt - t ensile st r engt h of t he t er r ain, f or t hey
low t unnels.
condit ion t he ef f icacy of ex cav at ion.
f ul st abilit y of t he t er r ain. The ex ist ence
of unconsolidat ed inf illing mat er ial can In sof t gr ound, t he essent ial cr it er ia ar e
2 - P H YSIC AL PA R A M ETERS aggr av at e t he r esult ing inst abilit y . cohesion and t he angle of f r ict ion, f or
t hey condit ion t he hold- up of t he f ace and
The pr esence of maj or discont inuit ies of t he ex cav at ion as a w hole.
2 .1 - Id e ntific a tio n can hav e a maj or ef f ect on t he choice of
t unnelling t echnique. The v er y high st r engt hs of some r ocks
ex clude t he use of boom- t y pe t unnelling
The t y pe of gr ound play s a decisiv e r ole Sl ur r y shi el ds and compr essed- ai r machines (unless t hey ar e highly cr ac-
in t he choice and design of a shield TBM. TBMs ar e gener ally mor e sensit iv e t o ked). Gr i pper - t y pe t unnel bor i ng and
Consequent ly t he par amet er s char act e- t he pr esence of di scont i nui t i es t han r eaming machines ar e v er y sensit iv e t o
r izing t he ident if icat ion of t he gr ound EPBMs. If t her e ar e maj or discont inui- low - st r engt h gr ound and may r equir e
must be ex amined car ef ully w hen choo- t ies (high densit y of f r act ur at ion), t he special adapt at ion of t he gr ipper pads.
sing t he ex cav at ion/ suppor t met hod. compr essed- air conf inement TBM may For main- beam and shield TBMs alike,
The most impor t ant of t he ident if icat ion hav e t o be eliminat ed f r om t he possible t he machine ar chit ect ur e, t he inst alled
par amet er s ar e plast icit y and - f or r ange. pow er at t he cut t er head, and t he choice
har dness, clogging pot ent ial, and abr a- and design of cut t ing t ools and cut t er head
In gener al t he ov er all per meabilit y of t he
siv eness - miner alogy w hich ar e par - ar e condit ioned by t he st r engt h of t he
t er r ain should be ex amined in conj unc- gr ound.
t i cul ar l y decisi v e i n t he sel ect i on of
t i on w i t h i t s di scont i nui t i es bef or e
shield TBM component s. If t her e is any chance of t unnel bear ing
select ing t he t y pe of conf inement .
Chemical analy sis of t he soil can be deci- capaci t y bei ng i nsuf f i ci ent , speci al
siv e in t he case of conf inement - t y pe t r eat ment may be necessar y f or t he
shield TBMs because of t he ef f ect soil 2 . 4 - A lt er a bilit y machine t o adv ance.
might hav e on t he addit iv es used in t hese
A l t er abi l i t y char act er i st i cs concer n
t echniques.
t er r ai n t hat i s sensi t i v e t o w at er . 3.2 - D efor m a b i l i t y
Alt er abilit y dat a should be obt ained at
2 .2 - G lo b a l a p p reci a tio n o f t he ident if icat ion st age.
Def or mabilit y of t he t er r ain may cause
q u a lit y j amming of t he TBM, especially in t he
Special at t ent ion should be giv en t o alt e- ev ent of conv er gence r esul t ing f r om
Global appr eciat ion of quali t y r esult s r abilit y w hen mechanized t unnelling is t o hi gh s t r es s es ( s ee par agr aph 1 ,
f r om combining par amet er s w hich ar e t ake place i n w at er - sensit iv e gr ound “ Nat ur al const r aint s” ).
easy t o measur e in t he labor at or y or in such as cer t ain molasses, mar ls, cer t ain In t he case of t unnel r eamer s and open-
si t u ( bor ehol e l ogs, RQD) and v i sual schist s, act iv e clay s, indur at ed clay s, f ace or mechanical- suppor t TBMs, t his
appr oaches. et c. cr it er ion af f ect s t he appr eciat ion of t he
Weat her ed z ones and z ones w i t h Alt er abilit y has an ef f ect on conf ine- r isks of cut t er head or shield j amming.
cont r ast ing har dness can cause specif ic ment - t y pe TBMs; it can r esult in changes In t he case of ex cessiv ely def or mable
dif f icult ies f or t he dif f er ent t unnelling being made t o t he design of t he machine mat er ial, t he design of TBM gr ipper pads
t echniques, e.g. f ace inst abilit y , insuf f i- and t he choice of addit iv es. w ill hav e t o be st udied car ef ully . The

IV-21
 Choosing mechanized tunnelling techniques
def or mabilit y of t he sur r ounding gr ound Abr asiv eness and har dness can be deci- mer s can ex cav at e t unnels of const ant
also af f ect s TBM guidance. If t he t unnel si v e w i t h r espect t o t ool w ear , t he shape only . The sect ional ar ea t hat can
lining is er ect ed t o t he r ear of t he t ails- st r uct ur e of t he cut t er head, and ex t r a- be ex cav at ed is r elat ed t o t he st abilit y
kin, at t ent ion should be paid t o t he r isk ct ion sy st ems (scr ew conv ey or , slur r y of t he f ace.
of def er r ed def or mat ion. pi pes, et c.) . How ev er , t he ex pect ed The sect ional ar ea of t unnels is decisiv e
w ear can be count er ed by using bor ing f or l ar ge- di amet er EPBMs ( pow er
In gr ound t hat sw el ls in cont act w it h
and/ or ex t r act ion addit iv es and/ or pr o-
w at er , t he r esul t i ng di f f i cul t i es f or r equir ed at t he cut t er head).
t ect ion or r einf or cement on sensit iv e
adv ancing t he machine ar e compar able The lengt h of t he pr oj ect can hav e an
par t s.
f or bot h slur r y shield and EPB machines, ef f ect on slur r y shield TBMs (pumping
in so f ar as t he sw elling is due t o t he dif - dist ance).
f usion and absor pt ion of w at er w it hin t he 5.2 - Stickin g - Clo g gin g
decompr essed gr ound ar ound t he t unnel.
Compr essed- air TBMs ar e less sensi- When t he pot ent ial t he mat er ial t o be 6 .2 - Ve r tica l a li g n m e nt
t iv e t o t his phenomenon. ex cav at ed has t o st ick or clog is know n,
t he cut t er s of boom- t y pe unit s, t unnel T he l i m i t s i m pos ed on t unnel l i ng
r eamer s, or shield TBMs can be adapt ed machi nes by t he v er t i cal pr of il e ar e
3. 3 - Liq u ef a ctio n p ote nti a l or use of an addit iv e env isaged. gener ally t hose of t he associat ed logis-
t ics. Main- beam t unnel bor ing and r ea-
Not applicable, ex cept if t her e is a r isk This par amet er alone cannot ex clude a
ming machines can be adapt ed t o bor e
of ear t hquake or if t he gr ound is par t i- t y pe of shield TBM; it is t her ef or e not inclined t unnels, but t he r equir ement f or
cular ly sensit iv e (sat ur at ed sand, et c.). decisiv e f or f ace- conf inement shields. special equipment t akes t hem bey ond t he
How ev er , t he t r end f or t he gr ound t o scope of t hese r ecommendat ions.
st ick must be ex amined w it h r espect t o
t he dev el opment of addi t i v es ( f oam, Wit h boom- t y pe unit s and open- f ace or
4 - H Y DR O GE OLO GIC AL admix t ur es, et c.) and t he design of t he m ec hani c al - s uppor t T BM s , w at er
PA R A M ETERS equipment f or chur ning and mix ing t he inf low can cause pr oblems in dow ngr ade
st icky spoil (agit at or s, j et t ing, et c.). dr iv es.
The pur pose of ex amining t he hy dr ogeo-
logical par amet er s of t he t er r ain is t o The t r anspor t of muck by t r ains and/ or
ensur e t hat it w ill r emain st able in t he conv ey or s is par t icular ly sensit iv e t o 6 . 3 - H ori z o nt a l a lig n m e nt
shor t t er m. The pr esence of high w at er t his par amet er .
pr essur es and/ or pot ent ial inf low r at es ❑ The use of boom- t y pe unit s imposes no
ent r aining mat er ial w ill pr ohibit t he use par t icular const r aint s.
of boom- t y pe machines and open- f ace or
5.3 - G ro u n d / m a chin e frictio n
❑ The use of main- beam t unnel bor ing
mechani cal - suppor t machi nes unl ess For shield TBMs t he pr oblem of gr ound and r eaming machines and of shield TBMs
accompany ing measur es such as gr ound f r ict ion on t he shield can be cr it ical in is limit ed t o cer t ain r adii of cur v at ur e
impr ov ement , gr oundw at er l ow er ing, gr ound w her e conv er gence is high. ( ev e n w i t h ar t i c ul at i on s on t h e
et c. ar e car r ied out . machines).
Wher e t her e is a r eal r isk of TBM j am-
Wat er pr essur e is also decisiv e w hen ming (conv er gence, sw elling, dilit ancy , ❑ Wi t h shi el d T BM s t he al i gnm ent
geological accident s (e.g. my lonit e) hav e et c.) t his par amet er has a par t icular ly af t er / bef or e br eak- i ns and br eakout s
t o be cr ossed, ir r espect iv e of w het her impor t ant ef f ect on t he design of t he should be st r aight f or at least t w ice t he
or not t hey ar e inf illed w it h loose soil. shield. lengt h of t he shield (since it is impossible
Gr ound per meabil i t y and hy dr ost at i c The lubr icat ion pr ov ided by t heir bent o- t o st eer t he machine w hen it is on it s slide
pr essur e ar e decisiv e f or TBMs using nit e slur r y makes slur r y shield TBMs cr adle).
compr essed- air , slur r y , or EPB conf i- l ess suscept i bl e t o t he pr obl ems of
nement . Compr essed- air machines may gr ound/ machine f r ict ion. 6 . 4 - En v iro n m e n t
ev en be r ej ect ed because of t hese f ac-
t or s, and t hey ar e par t icular ly decisiv e
f or EPBMs w hen t her e ar e likely t o be 5.4 - Prese nce o f g a s 6.4.1 - Se nsitivit y to settle m e nt
sudden v ar iat ions in per meabilit y . For Since boom- t y pe unit s, t unnel r eamer s,
slur r y shield TBMs, t he ef f ect s of t hese The pr esence of gas in t he gr ound can
main- beam TBMs, and open- f ace shield
par amet er s ar e at t enuat ed by t he f act det er mine t he equipment f it t ed t o t he
TBMs do not gener al l y pr ov i de any
t hat a f luid is used f or mucking out . machine.
immediat e suppor t , t hey can engender
set t lement at t he sur f ace. Set t lement
w ill be par t icular ly decisiv e in ur ban or
5 - O THER PA R A M ETERS 6 - PR O JECT C H A RA CTERIS- sensit iv e zones (t r ansit s below r out es
TI C S of communi cat i on such as r ai l w ay s,
pipelines, et c.).
5 .1 - A b r a siv e n ess - H a r d n e ss
6.1 - Dim e nsio ns a n d sections Sensit iv it y t o set t lement is gener ally
Ex cessi v el y hi gh abr asi v eness and decisiv e f or all TBM t y pes and can lead
har dness make it impossible or unecono- Boom- t y pe unit s can ex cav at e t unnels of t o ex clusion of a giv en t echnique.
m i c t o us e boom - t y pe t unnel l i ng any shape and sect i onal ar ea. Shiel d Open- f ace or mechanical- suppor t shield
machines. TBMs, main- beam machines, and r ea- TBMs ar e not suit able f or use in v er y

IV-22
 Choosing mechanized tunnelling techniques
def or mable gr ound. If t he t unnel lining is r at ion plant . This const r aint can hav e an encount er ed in ov er coming t he obst acle
er ect ed t o t he r ear of t he t ailskin, at t en- ef f ect on t he choice of TBM t y pe or ev en and t he need t o w or k f r om t he cut t er head
t ion should be paid t o t he r isk of def er - be decisiv e in int ensiv ely built - up zones. chamber .
r ed def or mat i on of t he sur r oundi ng Compr essed- ai r w or k necessar y f or
The addit iv es int r oduced int o t he cut t e-
gr ound. det ect i ng and deal i ng w i t h obst acl es
r head chamber of shield TBMs (bent o-
Wit h conf inement - t y pe TBMs, cont r ol of ni t e, poly mer , sur f act ant , et c.) may r equir es r eplacement of t he pr oduct s in
set t lement is closely linked t o t hat of imply const r aint s on disposal of spoil. t he c ut t er head c hamber ( pr oduct s
conf inement pr essur e. depending on t he conf inement met hod)
w it h compr essed air .
Wit h compr essed- air shields t he r isk of 6 . 5 - A n o m a lies in g ro u n d
set t lement lies in loss of air (sudden or The w or k r equir ed f or r eplacing t hem is:
gr adual). 6. 5.1 - G ro u n d / a ccid e nt h ete ro g e n e i- ❑ f ast er and simpler w it h a compr es-
Wit h slur r y shield TBMs t he r isk lies in ty sed- air TBM (in pr inciple)
t he qualit y of t he cake and in t he r egula- ❑ easy w it h a slur r y shield TBM
Mix ed har d r ock/ sof t gr ound gener ally
t ion of t he pr essur e. In r elat ion t o t his,
implies f ace- st abilit y and gr ipping pr o- ❑ longer and mor e dif f icult w it h an ear t h
t he “ air bubble” conf inement pr essur e
blems f or t unnelling t echniques w it h no pr essur e balance machine (ex t r act ion of
r egul at ion sy st em per f or ms par t i cu-
conf inement , and also int r oduces a r isk t he ear t h and subst it ut ion w it h slur r y t o
lar ly w ell.
of cav ing- in of t he r oof w her e t he gr ound f or m a sealing f ilm, f ollow ed by r emo-
Wit h EPBMs t he r isk lies in less pr ecise is sof t est . v al of t he bulk of t he slur r y and r eplace-
r egulat ion of t he conf inement pr essur e.
Mor eov er , t he annular space ar ound t he 6.5.2 - N a tur a l a n d a rtificia l obs- ment w it h compr essed air ).
shield is not pr oper ly conf ined, unless t a cl e s 6. 5.3 - Vo i d s
ar r angement s ar e made t o inj ect slur r y For “ open” t echniques it is essent ial t o Depending on t heir size, t he pr esence of
t hr ough t he cans. be able t o det ect geological accident s. For v oi ds can engender v er y subst ant i al
conf inement t echniques at t ent ion should dev iat ion f r om t he design t r aj ect or y ,
6.4.2 - Se nsitivit y to distur b a nce a n d
w or k constr a in ts be paid t o t he pr esence of obst acl es, especially v er t ically . They can also be a
w het her nat ur al or ar t if icial. Obst acles sour ce of dist ur bance t o t he conf inement
Slur r y shield machines r equir e a lar ge can hav e an ef f ect on t he choi ce of pr essur e, par t icular ly w it h compr es-
ar ea at t he sur f ace f or t he slur r y sepa- machi ne, depending on t he dif f icult ies sed- air or slur r y shield TBMs.

APPENDI X 3
G r o u n d cl a ssific a ti o n t a b l e (cf. G T7)

Cat égor y Descr i pt i on Ex ampl es RC ( Mpa)

R1 Ver y st r ong r ock St r ong quar t zi t e and basal t > 200
R2 a Ver y st r ong gr ani t e, por phy r y , v er y st r ong
St r ong r ock sandst one and l i mest one 200 à 120

R2 b Gr ani t e, v er y r esi st ant or sli ght l y dol omi t i zed sandst one and 1 2 0 à 6 0
l i mest one, mar bl e, dol omi t e, compact congl omer at e
R3 a Or di nar y sandst one, si l i ceous schi st or 60 à 40
Moder at el y st r ong r ock schi st ose sandst one, gnei ss
R3 b Cl ay ey schi st , moder at el y st r ong sandst one and li mest one,
40 à 20
compact mar l , poor l y cement ed congl omer at e
Schi st or sof t or hi ghl y cr acked l i mest one, gy psum,
20 à 6
R4 Low st r engt h r ock hi ghl y cr acked or mar l y sandst one, puddi ngst one, chal k
R5 a Ver y l ow st r engt h r ock and Sandy or cl ay ey mar ls, mar l y sand, gy psum
6 à 0, 5
consol i dat ed cohesi v e soi l s or w eat her ed chal k
R5 b Gr av el l y al l uv i um, nor mal l y consol i dat ed cl ay ey sand < 0, 5
R6 a Pl ast i c or sl i ght l y consol i dat ed soi l s Weat her ed mar l , plai n cl ay , cl ay ey sand, f i ne l oam
R6 b Peat , sil t and l i t t le consol i dat ed mud, f i ne non- cohesi v e sand

IV-23
 Choosing mechanized tunnelling techniques
APPENDI X 3
M e c h a n i z e d t u n n e ll i n g d a t a s h e e ts ( u p t o 3 1 / 1 2 / 9 9 ).
Bored Bored Geology
Project Dat e lengt h diamet er
(m) (m)
1 Echaillon D 68 1 97 2 -19 7 3 4 3 62 5 .8 0 Gneiss, flysch, limest one Wirt h
2 La Coche D 77 1 97 2 -1 9 73 5287 3 .0 0 Limest one, sandst one, breccia Robbins
3 CERN SPS H 64 1 97 3 -19 7 4 6 5 51 4 .8 0 Molasse Robbins
4 RER Chât elet -Gare de Lyon C 64 1 9 73 -1 97 5 51 0 0 7 .0 0 Limest one Robbins
5 Belledonne D 64 19 7 4 -1 9 78 9998 5 .8 8 Schist , sediment ary granit e Wirt h
6 Bramefarine D 67 1 97 5 -19 7 7 3 7 00 8 .1 0 Limest one, schist Robbins
7 Lyons met ro - Crémaillère C 64 1 97 6 22 0 3 .0 8 Gneiss, granit e Wirt h
8 Galerie du Bourget C 67 1 97 6 -19 7 8 4 8 45 6 m2 Limest one, molasse Alpine
9 Monaco - Service t unnel H 64 19 7 7 913 3 .3 0 Limest one, marne Robbins
10 Grand Maison - Eau Dolle D 64 1 97 8 83 9 3 .6 0 Gneiss, schist , dolomit e Wirt h
11 West ern Oslofjord G 77 1 97 8 -19 8 4 1 0 50 0 3 .0 0 Slat e, limest one, igneous rock Bouygues
12 Brevon D 66 1 97 9 -19 8 1 4 1 50 3 .0 0 Limest one, dolomit e, ot her Bouygues
calcareous rock (malm)
1 3 Grand Maison D 75 19 7 9 -1 98 2 54 6 6 3 .6 0 Gneiss, schist Wirt h
( penst ocks and service shaft )
1 4 Marignan aqueduct F 66 1 9 79 -1 98 0 48 0 5.52 m2 Limest one Alpine
1 5 Super Bissort e D 73 1 9 80 -1 98 1 29 7 5 3 .6 0 Schist , sandst one Wirt h
1 6 Pouget D 66 1 98 0 -19 8 1 3 9 99 5 .0 5 Gneiss Wirt h
1 7 Grand Maison - Vaujany D 75 19 8 1 -1 9 83 5400 7 .7 0 Lipt init e, gneiss, amphibolit e Robbins
1 8 Vieux Pré D 68 19 8 1 -1 9 82 1257 2 .9 0 Sandst one, conglomerat ee Bouygues
1 9 Haut e Romanche Tunnel D 73 1 9 81 -1 98 2 28 6 0 3 .6 0 Limest one, schist , cryst alline sandst one Wirt h
2 0 Cilaos F 80 1 98 2 -19 8 4 5 7 01 3 .0 0 Basalt , t uff Wirt h
2 1 Monaco - t unnel No. 6 A 66 1 98 2 18 3 5 .0 5 Limest one, dolomit e Wirt h
2 2 Ferrières D 79 1 9 82 -1 98 5 43 1 3 5 .9 0 Schist , gneiss Wirt h
2 3 Durolle D 79 1 98 3 -19 8 4 2 1 39 3 .4 0 Granit e, quart z, microgranit e Wirt h
2 4 Mont fermy D 80 1 98 3 -19 8 5 5 0 40 3 .5 5 Gneiss, anat exit e, granit e Robbins
2 5 CERN LEP ( machines 1 and 2) H 82 1 9 85 -1 98 6 14 6 80 4 .5 0 Molasse Wirt h
2 6 CERN LEP (machine 3) H 82 19 8 5 -1 9 87 4706 4 .5 0 Molasse Wirt h
2 7 Val d' Isère funicular B 97 1 98 6 16 8 9 4 .2 0 Limest one, dolomit e, cargneule Wirt h
(cellular dolomit e)
28 Calavon and Luberon F 97 1 98 7 -19 8 8 2 7 87 3 .4 0 Limest one Wirt h
29 Takamaka II D 101 1 9 85 -1 98 7 48 0 3 3 .2 0 Basalt , t uff, agglomerat es Bouygues
30 Oued Lakhdar D 10 1 19 8 6 -1 9 87 6394 4.5 6 / 4.8 0 Limest one, sandst one, marl Wirt h
31 Paluel nuclear power plant E 1 05 1 98 0 -19 8 2 2 4 27 5 .0 0 Chalk Zokor
32 Penly nuclear power plant E 1 05 1 98 6 -19 8 8 2 5 10 5 .1 5 Clay Zokor
33 Lyons river crossing - met ro line D C 10 6 19 8 4 -1 9 87 2 x 1 23 0 6 .5 0 Recent alluvium and granit ic sand Bade
34 Lille met ro, line 1 b - Package 8 C 10 6 19 8 6 -1 9 87 1000 7 .6 5 Whit e chalk and flint FCB/ Kawasaki
35 Lille met ro, Line 1 b - Package 3 C 10 6 19 8 6 -1 9 88 3259 7 .7 0 Clayey sand and silt Herrenknecht
36 Villejust t unnel B 1 06 1 98 6 -19 8 8 4 8 05 9 .2 5 Font ainebleau sand Bade/ Theelen
+ 4798 (2 machines)
37 Bordeaux: Cauderan-Naujac G 10 6 19 8 6 -1 9 88 1 9 3 6 5 .0 2 Sand, marl and limest one Bessac
38 Caracas met ro: package PS 01 C 1 07 1 98 6 -1 9 87 2 x 1 564 5 .7 0 Silt y-sandy alluvium, gravel, and clay Lovat
39 Caracas met ro: package CP 0 3 C 1 07 1 98 7 2 x 2 131 5 .7 0 Weat hered micaschist and silt y sand Lovat
40 Caracas met ro: package CP 0 4 C 107 1 9 87 -1 98 8 2 x 71 4 5 .7 0 Micaschist Lovat
41 Singapore met ro: package 1 06 C 1 07 1 98 5 -19 8 6 2 6 00 5 .8 9 Sandst one, marl and clay Grosvenor
42 Bordeaux: " boulevards" G 113 1 9 89 -1 99 0 14 6 1 4 .3 6 Karst ic limest one and alluvium Bessac
main sewers Ø3 8 0 0
43 Bordeaux: Avenue de la Libérat ion G 1 1 3 1 9 88 -1 98 9 91 8 2 .9 5 Karst ic limest one and alluvium Bessac
Ø2 2 0 0
44 St Maur-Crét eil, sect ion 2 G 1 13 1 98 8 -19 9 0 1 5 30 3 .3 5 Old alluvium and boulders FCB
45 Crosne-Villeneuve St Georges G 113 1 9 88 -1 99 0 91 1 2 .5 8 Weat hered marl and indurat ed limest one Howden
46 Channel Tunnel T1 B 114 1 9 88 -1 99 0 15 6 18 5 .7 7 Blue chalk Robbins
47 Channel Tunnel T2 -T3 B 114 1 9 88 -1 99 1 20 0 09 8 .7 8 Blue chalk Robbins/
+1 8 86 0 Kawasaki

*AITES classif icat ion of project t ypes

A 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 f acilit ies - K mines -
IV-24
 Choosing mechanized tunnelling techniques

(A PPE N DI X 3)
Bored Bored Geology
Project Dat e lengt h diamet er
( m) ( m)
48 Channel Tunnel T4 B 1 1 4 1 9 8 8-1 9 89 3 16 2 5.6 1 Grey and whit e chalk Mit subishi
49 Channel Tunnel T5 -T6 B 1 1 4 19 8 8 -1 9 90 2 x 3 26 5 8.64 Grey and whit e chalk Mit subishi
50 Sèvres - Achères: Package 3 G 1 21 1 9 8 9 -1 99 1 35 5 0 4 .05 Coarse limest one, sand, upper Landenian
clay (fausses glaises), plast ic clay, Herrenknecht
Mont ian marl, chalk
51 Sèvres - Achères: Packages 4 and 5 G 1 2 1 1 9 88 -1 9 90 3 31 2 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 1 98 9 - 1 9 90 1 16 0 7.6 4 Marl wit h beds of gypsum Howden
54 Bordeaux Caudéran -
Naujac Rue de la Libert é G 1 26 1 99 1 150 3.8 4 Karst ic limest one Bessac
55 Bordeaux Amont Taudin G 1 26 1 9 91 5 00 2 .8 8 Alluvium and karst ic limest one Howden
56 Rouen " Mét robus" C 1 26 1 9 93 8 00 8 .3 3 Black clay, middle Albian sand and Gault clay Herrenknecht
57 Toulouse met ro: Package 3 C 1 3 1 1 9 8 9 -1 9 91 3 15 0 7.6 5 Clayey-sandy molasse and beds FCB /
of sandst one Kawasaki
58 Toulouse met ro: Packages 4 and 5 C 1 3 1 19 9 0 -1 9 9 1 1 5 87 5 .6 Molasse Lovat
+1 4 87
59 Lille met ro: Line 2 Package 1 C 1 3 2 1 9 92 - 19 9 4 5 0 43 7 .6 5 Flanders clay FCB
60 Lille met ro: Line 2 Sect ion b C 1 3 2 19 9 2 - 1 99 3 14 7 3 7 .6 5 Chalk, clay, and sandy chalk FCB
61 St Maur: VL3 c main sewer G 1 3 3 19 9 2 - 1 99 4 13 5 0 3 .5 Very het erogenous plast ic clay, sand,
coarse limest one,andupper Landenian clay Herrenknecht
62 Lyons met ro: Line D
Vaise - Gorge de Loup C 1 33 1 99 3 - 1 9 95 2 x 8 75 6 .2 7 Sand, gravel, and clayey silt Herrenknecht
63 METEOR Line 1 4 C 1 4 2 1 9 93 - 19 9 5 4 5 00 8 .6 1 Sand, limest one, marl,upper Lut et ian
marl/ limest one ( caillasses) HDW
64 RER Line D Chat elet / Gare de Lyon C 1 4 2 19 9 3 - 1 99 4 2 x 1 60 0 7.08 Coarse limest one Lovat
65 Cleuson Dixence Package D D 1 4 2 19 9 4 - 1 99 6 23 0 0 4 .77 Limest one, quart zit es, schist , sandst one Robbins
Inclined shaft
66 Cleuson Dixence Inclined shaf t D 1 42 1 99 4 - 1 9 96 4 00 4 .4 Limest one, schist , sandst one Lovat
67 Cleuson Dixence Package B
Headrace t unnel D 1 53 1 99 4 - 1 9 96 7 40 0 5.6 Schist and gneiss Wirt h
68 Cleuson Dixence Package C
Headrace t unnel D 1 52 1 99 4 - 1 9 96 7 40 0 5.8 Schist , micachist , gneiss, and quart zit e Robbins
69 EOLE B 1 46 1 99 3 - 1 9 96 2 x 1 7 00 7 .4 Sands, marl and ' caillasse' marl/ limest one,
sandst one and limest one Voest Alpine
70 Sout h-east plat eau G 1 4 6 19 9 4 - 19 9 7 39 2 5 4 .4 2 Molasse sand, moraine, alluvium NFM
out fall sewer ( EPSE)
71 Cadiz: Galerie Guadiaro Majaceit e F 1 4 8 1 9 95 - 19 9 7 1 2 20 0 4.8 8 Limest one, consolidat ed clay NFM/ MHI
72 Lille met ro Line 2 Package 2 C 1 4 8 1 9 95 - 19 9 7 3 9 62 7 .6 8 Flanders clay FCB
73 Nort h Lyons bypass,
Caluire t unnel, Nort h t ube A 1 50 1 99 4 - 1 9 96 3 25 2 11 .0 2 Gneiss, molasse, sands and conglomerat e NFM
74 Nort h Lyons bypass, Caluire t unnel,
Sout h t ube A 1 5 0 1 9 97 - 19 9 8 3 2 50 1 1.0 2 Gneiss, molasse, sand, and conglomerat e NFM
75 St orebaelt rail t unnels B 1 5 0 19 9 0 - 1 99 5 14 8 24 8 .7 8 Clay and marl Howden
76 St rasbourg t ram line C 1 50 1 99 2 - 1 9 93 1 19 8 8.3 Sands and graviers Herrenknecht
77 Thiais main sewer Package 1 G 1 5 4 19 8 7 - 1 98 9 44 0 4 2 .84 Marl and clay Lovat
78 Ant ony urban area main sewer G 1 54 1 98 9 14 8 3 2 .8 4 Alluvium, limest one, marl Lovat
79 Fresnes t ransit G 1 54 1 99 1 280 2.84 Marl and alluvium Lovat
80 Main sewer beneat h CD 67 G 154 1991 6 70 2 .84 Marl Lovat
road in Ant ony
81 Duplicat ion of main sewer,
Rue de la Barre in Enghien G 1 5 4 19 9 2 - 19 9 3 8 0 7 2.84 Sand, marly limest one, marl Lovat
82 Bièvre int ercept or G 1 54 1 99 3 10 0 0 2 .84 Marl and alluvium Lovat
83 Duplicat ion of main sewer,
Ru des Espérances - 8t h t ranche G 1 5 6 19 9 3 - 1 99 4 13 8 7 2 .54 Limest one, sand Lovat
84 Duplicat ion of main sewer,
Ru des Espérances - 9t h t ranche G 1 56 1 99 5 - 1 99 6 12 0 0 2 .54 Coarse limest one, marly limest one Lovat
85 Duplicat ion of main sewer,
Ru des Espérances - 10 t h t ranche G 1 5 6 1 9 96 - 19 9 7 4 69 2 .54 Marly limest one Lovat

IV-25