aftes recommendations...aftes new recommendations on choosing mechanized tunnelling techniques text...

Choosing mechanized tunnelling techniques

GT4R3A1

www.aftes.asso.fr

ASSOCIATION FRANÇAISE DES TUNNELSET DE L’ESPACE SOUTERRAIN

Organization member of the AFTES

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AFTES NEW RECOMMENDATIONS ON

CHOOSING MECHANIZED TUNNELLING TECHNIQUES

Text led by P. LONGCHAMP, Chairman of AFTES Work Group No. 4 - Technical Manager, Underground Works - BOUYGUES Travaux Publics

with the assistance ofA. SCHWENZFEIER, CETU

These subgroups were moderated byJ.M. DEMORIEUX, SETEC - F. MAUROY, SYSTRA - J.M. ROGEZ, RATP - J.F. ROUBINET, GTM

These recommendations were drawn up by a number of sub work groups whose members were:A. AMELOT, SPIE BATIGNOLLES - D. ANDRE, SNCF - A. BALAN, SNCF - H. BEJUI✝, AFTES -

F. BERTRAND, CHANTIERS MODERNES - F. BORDACHAR, QUILLERY - P. BOUTIGNY, CAMPENON BERNARD SGE - L. CHANTRON, CETU - D. CUELLAR, SNCF - J.M. FREDET, SIMECSOL - J.L. GIAFFERI, EDF-GDF -

J. GUILLAUME, PICO GROUPE RAZEL - P. JOVER✝, S.M.A.T. - Ch. MOLINES, FOUGEROLLES BALLOT - P. RENAULT, PICO GROUPE RAZEL - Y. RESCAMPS, DESQUENNE ET GIRAL

Acknowledgements are due to the following for checking this document:M. MAREC, MISOA - M.C. MICHEL, OPPBTP - P. BARTHES, AFTES

A.F.T.E.S. will be pleased to receive any suggestions concerning these recommendations

Version 1 - 2000 -approved by the Technical Committee of 23 November 1999 Translated in 2000

INTRODUCTION

T he f i rst recommendat ions onmechanized tunnelling techniquesissued in 1986 essentially concerned

hard-rock machines.

The shape of the French market has chan-ged a great deal since then. The develop-ment of the hydropower sector which wasfirst a pioneer, then a big user of mechani-zed tunnelling methods has peaked and isnow declining. In its place, tunnels nowconcern a range of generally urban works,i.e. sewers, metros, road and rail tunnels.

Since most of France’s large urban centresare built on the flat, and often on rivers, thepredominant tunnelling technique has alsoswitched from hard rock to loose or softground, often below the water table.

To meet these new requirements, Francehas picked up on trends from the east(Germany and Japan).

Faced with France’s extremely varied geo-logy, project owners, contractors, engi-neers, and suppliers have adapted theseforeign techniques to their new conditionsat astonishing speed.

Now, this new French technical culture isbeing exported throughout the world(Germany, Egypt, United Kingdom,Australia, China, Italy, Spain, Venezuela,Denmark, Singapore, etc.).

This experience forms the basis for theserecommendations, drawn up by a group of25 professionals representing the differentbodies involved.

Before the large number of parameters andselection criteria, this group soon realizedthat it was not possible to draw up an ana-lytical method for choosing the most appro-priate mechanized tunnelling method, but

rather that they could provide a documentwhich:

1) clarifies the different techniques, descri-bing and classifying them in differentgroups and categories,

2) analyzes the effect of the selection crite-ria (geological, project, environmentalaspects, etc.),

3) highlights the special features of eachtechnique and indicates its standard scopeof application, together with the possibleaccompanying measures.

In other words, these new recommenda-tions do not provide ready-made answers,but guide the reader towards a reasonedchoice based on a combination of technicalfactors.

Beaumont machine, 1882. First attempt to drive a tunnel beneath the English Channel.

TUNNELS ET OUVRAGES SOUTERRAINS – HORS-SERIE N° 1 – 2005

• 137 •

1. PURPOSE OF THESE RECOMMENDATION

2. MECHANIZED TUNNELLING TECHNIQUES

2.1. Definition and limits

2.2. Basic functions2.2.1. Excavation2.2.2. Support and opposition to hydrostatic pressure2.2.3. Mucking out

2.3. Main risks and advantages of mechanized tunnelling techniques

3. CLASSIFICATION OF MECHANIZED TUNNELLINGTECHNIQUES

4. DEFINITION OF THE DIFFERENT MECHANIZEDTUNNELLING TECHNIQUES CLASSIFIED IN CHAPTER 3

4.1. Machines not providing immediate support4.1.1. General4.1.2. Boom-type tunnelling machine4.1.3. Hard rock TBM4.1.4. Tunnel reaming machine

4.2. Machines providing immediate support peripherally4.2.1. General4.2.2. Open-face gripper shield TBM4.2.3. Open-face shield TBM4.2.4. Double shield

4.3. Machines providing immediate peripheral andfrontal support simultaneously

4.3.1. General4.3.2. Mechanical-support TBM4.3.3. Compressed-air TBM4.3.4. Slurry shield TBM4.3.5. Earth pressure balance machine4.3.6. Mixed-face shield TBM

5. EVALUATION OF PARAMETERS FOR CHOICE OFMECHANIZED TUNNELLING TECHNIQUES

5.1. General

5.2. Evaluation of the effect of elementary selectionparameters on the basic functions of mechanized tun-nelling techniques

5.3. Evaluation of the effect of elementary selectionparameters on mechanized tunnelling solutions

6. SPECIFIC FEATURES OF THE DIFFERENT TUNNELLING TECHNIQUES

6.1. Machines providing no immediate support6.1.1. Specific features of boom-type tunnelling

machines6.1.2. Specific features of Hard rock TBMs6.1.3. Specific features of tunnel reaming machines

6.2. Specific features of machines providing immediate peripheral support

6.2.1. Specific features of open-face gripper shieldTBMs

C O N T E N T SC O N T E N T S

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6.2.2. Specific features of open-face shield TBMs6.2.3. Specific features of double shield TBMs

6.3. Specific features of TBMs providing immediatefrontal and peripheral support

6.3.1. Specific features of mechanical-support shieldTBMs

6.3.2. Specific features of compressed-air TBMs6.3.3. Specific features of slurry shield TBMs6.3.4. Specific features of earth pressure balance

machines

7. APPLICATION OF MECHANIZED TUNNELLINGTECHNIQUES

7.1. Machines not providing immediate support7.1.1. Boom-type tunnelling machines7.1.2. Hard rock TBMs7.1.3. Tunnel reaming machines

7.2. Machines providing immediate peripheral support7.2.1. Open-face gripper shield TBMs7.2.2. Open-face shield TBMs7.2.3. Open-face double shield TBMs

7.3. Machines providing immediate frontal and peripheral support

7.3.1. Mechanical-support shield TBMs7.3.2. Compressed-air TBMs7.3.3. Slurry shield TBMs7.3.4. Earth pressure balance machines

8. TECHNIQUES ACCOMPANYING MECHANIZEDTUNNELLING

8.1. Preliminary investigations from the surface8.1.1. Environmental impact assessment8.1.2. Ground conditions8.1.3. Resources used

8.2. Forward probing

8.3. Ground improvement

8.4. Guidance

8.5. Additives

8.6. Data logging

8.7. Tunnel lining and backgrouting8.7.1. General8.7.2. Lining8.7.3. Backgrouting

9. HEALTH AND SAFETY

9.1. Design of tunnel boring machines

9.2. Use of TBMs

APPENDIX 1

APPENDIX 2

APPENDIX 3

APPENDIX 4


• 138 •

G. T. n° 4 - Choosing mechanized tunnelling techniques


• 139 •

1 - PURPOSE OF THESERECOMMENDATIONSThese recommendations supersede theprevious version which was issued in 1986and which dealt essentially with hard-rockor “main-beam” tunnel boring machines(TBMs).

The scope of this revised version has beenbroadened to include all (or nearly all) typesof tunnelling machines.

The recommendations are intended toserve as a technical guide for the difficultand often irreversible choice of a tunnelboring machine consistent with the expec-ted geological and hydrogeological condi-tions, the environment, and the type of thetunnel project.

To start with, the different kinds of machinesare classified by group, category, and type.Since all the machines share the commoncharacteristic of excavating tunnels mecha-nically, the first criterion for classification isnaturally the machine's ability to provideimmediate support to the excavation.

This is followed by a list of the parameterswhich should be analyzed in the selectionprocess, then by details of the extent towhich these parameters affect mechanizedtunnelling techniques, and finally a series offundamental comments on the differentkinds of machine.

By combining these parameters, decision-makers will arrive at the optimum choice.

The principal specific features of the diffe-rent groups and categories of techniquesare then outlined, and the fundamentalfields of application of each category areexplained.

Lastly, accompanying techniques, whichare often common to several techniquesand vital for proper operation of themachine, are listed and detailed. It shouldbe noted that data logging techniqueshave meant remarkable progress has beenmade in technical analysis of the problemsthat can be encountered.

Since health and safety are of constantconcern in underground works, a specialchapter is devoted to the matter.

2 - MECHANIZED TUNNEL-LING TECHNIQUES

2.1 - DEFINITION ANDLIMITS

For the purposes of these recommenda-tions, “mechanized tunnelling techniques”

(as opposed to the so-called “conventio-nal” techniques) are all the tunnelling tech-niques in which excavation is performedmechanically by means of teeth, picks, ordiscs. The recommendations thereforecover all (or nearly all) categories of tunnel-ling machines, ranging from the simplest(backhoe digger) to the most complicated(confinement-type shield TBM).

The mechanized shaft sinking techniquesthat are sometimes derived from tunnellingtechniques are not discussed here.

For drawing up tunnelling machine supplycontracts, contractors should refer to therecommendations of AFTES WG 17,“Pratiques contractuelles dans les travauxsouterrains ; contrat de fourniture d’un tun-nelier” (Contract practice for undergroundworks; tunnelling machine supply contract)(TOS No. 150 November/December 1998).

2.2 - BASIC FUNCTIONS

2.2.1 - Excavation

Excavation is the primary function of allthese techniques.

The two basic mechanized excavationtechniques are:

• Partial-face excavation

• Full-face excavation

With partial-face excavation, the excava-tion equipment covers the whole sectionalarea of the tunnel in a succession of sweepsacross the face.

With full-face excavation, a cutterhead -generally rotary - excavates the entire sec-tional area of the tunnel in a single opera-tion.

2.2.2 - Support and opposition tohydrostatic pressure

Tunnel support follows excavation in thehierarchy of classification.

“Support” here means the immediate sup-port provided directly by the machine(where applicable).

A distinction is made between the tech-niques providing support only for the tun-nel walls, roof, and invert (peripheral sup-port) and those which also support thetunnel face (peripheral and frontal sup-port).

There are two types of support: passive andactive. Passive or “open-face” supportreacts passively against decompression ofthe surrounding ground. Active or “confi-nement-pressure” support provides activesupport of the excavation.

Permanent support is sometimes a directand integral part of the mechanized tun-nelling process (segmental lining for ins-tance). This aspect has been examined inother AFTES recommendations and is notdiscussed further here.

Recent evolution of mechanized tunnellingtechniques now enables tunnels to be dri-ven in unstable, permeable, and water-bearing ground without improving theground beforehand. de ceux-ci.This callsfor constant opposition to the hydrostaticpressure and potential water inflow. Onlyconfinement-pressure techniques meetthis requirement.

2.2.3 - Mucking out

Mucking out of spoil from the tunnel itselfis not discussed in these recommenda-tions. However, it should be recalled thatmucking out can be substantially affectedby the tunnelling technique adopted.Inversely, the constraints associated withmucking operations or spoil treatmentsometimes affect the choice of tunnellingtechniques.

The basic mucking-out techniques are:

• haulage by dump truck or similar

• haulage by train

• hydraulic conveyance system

• pumping (less frequent)

• belt conveyors

2.3 - MAIN RISKS ANDADVANTAGES OF MECHANIZED TUNNELLINGTECHNIQUES

The advantages of mechanized tunnellingare multiple. They are chiefly:

• enhanced health and safety conditions forthe workforce,

• industrialization of the tunnelling process,with ensuing reductions in costs and lead-times,

• the possibility some techniques provideof crossing complex geological and hydro-geological conditions safely and economi-cally,

• the good quality of the finished product(surrounding ground less altered, precastconcrete lining segments, etc.)

However, there are still risks associated withmechanized tunnelling, for the choice oftechnique is often irreversible and it is oftenimpossible to change from the techniquefirst applied, or only at the cost of immense

AFTES



• 140 •

upheaval to the design and/or the econo-mics of the project.

Detailed analysis of the conditions underwhich the project is to be carried out shouldsubstantially reduce this risk, something forwhich these recommendations will be ofgreat help. The experience and technicalskills of tunnelling machine operators arealso an important factor in the reduction ofrisks.

3 - CLASSIFICATION OFMECHANIZED TUNNELLINGTECHNIQUESIt was felt to be vital to have an official clas-sification of mechanized tunnelling tech-niques in order to harmonize the termino-logy appl ied to the most commonmethods.

The following table presents this classifica-tion. The corresponding definitions aregiven in Chapter 4.

The table breaks the classification downinto groups of machines (e.g. boom-type

unit) on the basis of a preliminary divisioninto types of immediate support (none,peripheral, peripheral and frontal) provi-ded by the tunnelling technique.

To give more details on the different tech-niques, the groups are further broken downinto categories and types.

4 - DEFINITION OF THE DIF-FERENT MECHANIZED TUN-NELLING TECHNIQUESCLASSIFIED IN CHAPTER 3

4.1 - MACHINES NOT PROVIDING IMMEDIATESUPPORT

4.1.1 - General

Machines not providing immediate sup-port are necessarily those working inground not requiring immediate and conti-nuous tunnel support.

4.1.2 - Boom-type tunnellingmachine

Boom-type units (sometimes called “tun-nel heading machines”) are machines witha selective excavation arm fitted with a toolof some sort. They work the face in a seriesof sweeps of the arm. Consequently thefaces they excavate can be both varied andvariable. The penetration force of the toolsis resisted solely by the weight of themachineLa réaction à.

This group of machines is fitted with one ofthree types of tool:

• Backhoe, ripper, or hydraulic impact brea-ker

• In-line cutterhead (roadheader)

• Transverse cutterhead (roadheader)

AFTES data sheets: No. 8 – 14

4.1.3 - Hard rock TBM

A Hard rock TBM has a cutterhead thatexcavates the full tunnel face in a singlepass.

The thrust on the cutterhead is reacted by

CLASSIFICATION OF MECHANIZED TUNNELLING TECHNIQUES

*For microtunnellers (diameter no greater than 1200 mm), refer to the work of the ISTT.**Machines used in pipe-jacking and pipe-ramming are included in these groups.

Hard rock TBM

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➀ Transverse cutterhead

Boom➁Muck conveyor➂

Loading apron

Crawler chassis

➃➄

Photo 4.1.2 - RoadheaderSchéma 4.1.2

➀➁

➃ ➄

Photo 4.1.4 - Sauges tunnel (Switzerland)

bearing pads (or grippers) which pushradially against the rock of the tunnel wall.

The machine advances sequentially, in twophases:

• Excavation (the gripper unit is stationary)

• Regripping

Spoil is collected and removedrearwards by the machine itself.

This type of TBM does not playan active role in immediate tun-nel support.

AFTES data sheets: No. 1 to 7,10 to 13, 15 to 24, 26 to 30, 67

4.1.4 - Tunnel reaming machine

A tunnel reaming machine has the same basic functionsas a Hard rock TBM. It bores the final section from anaxial tunnel (pilot bore) from which it pulls itself forwardby means of a gripper unit.

➀ Pilot bore

gripper unit (traction)➁

➁

Cutterhead➂Rear support

Muck conveyor➃➃➄

➄

Photo 4.1.3 - Lesotho Highlands Water Project

▼

▼

▼

▼

(Schéma and photo 4.1.4).

➂

➀ ➁➂ ➃

➄

➀ Cutter head

Conveyor➁Front gripper➂Rear gripper

Rear lift leg➃➄

➀➂

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• 142 •

4.2 - MACHINES PROVIDINGIMMEDIATE PERIPHERALSUPPORT

4.2.1 - General

Machines providing immediate peripheralsupport only belong to the open-face TBMgroup.

While they excavate they also support the

sides of the tunnel. The tunnel face is notsupported. d’aucune façon.

They can have two types of shield:

• one-can shield,

• shield of two or more cans connected byarticulations.

The different configurations for peripheral-support TBMs are detailed below.

4.2.2 - Open-face gripper shieldTBM

A gripper shield TBM corresponds to thedefinition given in § 4.1.32 except that it ismounted inside a cylindrical shield incor-porating grippers.

The shield provides immediate passiveperipheral support to the tunnel walls.

AFTES data sheet: N° 25

Photo 4.2.2 - Main CERN tunnel

➀ Cutterhead

Muck extraction conveyor➁ ➅ Muck transfer conveyor

Motor➆Segment erector➇

Télescopic section➂Thrust ram

Grippers (radial thrust)

➃

➄

4.2.3 - Open-face shield TBM

An open-face shield TBM is fitted witheither a full-face cutterhead or an excava-tor arm like those of the different boom-type units. To advance and tunnel, the

TBM's longitudinal thrust rams reactagainst the tunnel lining erected behind itby a special erector incorporated into theTBM.

AFTES data sheets: No. 31 - 32 - 41 - 66

▼

▼

➀ Cutterhead

Shield➁

⑥ Muck extraction conveyor

Muck transfer conveyor➆Gathering arm➇

➈➉ Motor

Tailskin articulation (option)

Thrust ring

Muck hopperArticulation (option)➂Thrust ram

Segment erector➃➄

Photo 4.2.3Athens metro

▼

▼

11

12

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• 143 •

4.2.4 - Double shield

A double shield is a TBM with a full-face cut-terhead and two sets of thrust rams thatreact against either the tunnel walls (radialgrippers) or the tunnel lining. The thrust

method used at any time depends on thetype of ground encountered. With longitu-dinal thrust, segmental lining must be ins-talled behind the machine as it advances.

The TBM has three or more cans connectedby articulations and a telescopic central

unit which relays thrust from the grip-ping/thrusting system used at the time tothe front of the TBM.

AFTES data sheets: No. 65 – 68 – 71 ▼

▼

➀ Cutterhead➁ Front unit➂ Telescopic section➃ Gripper unit➄ Tailskin ⑥ Main thrust rams

➆ Longitudinal thrust rams➇ Grippers➈ Tailskin articulation➉ Segment erector

Muck extraction conveyorMuck transfer conveyor

Photo 4.2.4 - Salazie water transfer project(Reunion Island)

4.3 - MACHINES PROVIDINGIMMEDIATE PERIPHERALAND FRONTAL SUPPORTSIMULTANEOUSLY

4.3.1 - General

The TBMs that provide immediate per-ipheral and frontal support simultaneouslybelong to the closed-faced group.

They excavate and support both the tunnelwalls and the face at the same time.

Except for mechanical-support TBMs, they

all have what is called a cutterhead cham-ber at the front, isolated from the rearwardpart of the machine by a bulkhead, in whicha confinement pressure is maintained inorder to actively support the excavationand/or balance the hydrostatic pressure ofthe groundwater.

The face is excavated by a cutterhead wor-king in the chamber.

The TBM is jacked forward by rams pushingoff the segmental lining erected inside theTBM tailskin, using an erector integratedinto the machine.

4.3.2 - Mechanical-support TBM

A mechanical-support TBM has a full-facecutterhead which provides face support byconstantly pushing the excavated materialahead of the cutterhead against the sur-rounding ground.

Muck is extracted by means of openings onthe cutterhead fitted with adjustable gatesthat are controlled in real time.

AFTES data sheets: No. 38 – 39 – 40 – 51 –58 – 64

➀ Cutterhead➁ Shield➂ Articulation (option)➃ Thrust ram➄ Segment erector⑥ Muck extraction conveyor

➆ Muck transfer conveyor➇ Muck hopper (with optional gate)➈ Cutterhead drive motor➈ Gated cutterhead openings

Peripheral seal between cutterhead and shieldTailskin articulation (option)

▼

▼

Photo 4.3.2 RER Line D (Paris)

11

12

11

12

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• 144 •

4.3.3 - Compressed-air TBM

A compressed-air TBM can have either afull-face cutterhead or excavating arms likethose of the different boom-type units.Confinement is achieved by pressurizingthe air in the cutting chamber.

Muck is extracted continuously or intermit-tently by a pressure-relief discharge systemthat takes the material from the confine-ment pressure to the ambient pressure inthe tunnel.

AFTES data sheets: No. 37 – 42 – 43 – 53 –54 – 70

Excavating armShieldCutting chamberAirtight bulkheadThrust ramArticulation (option)

Tailskin sealAirlock to cutting chamberSegment erectorScrew conveyor (or conveyor and gate)Muck transfer conveyor Photo 4.3.3 - Compressed air TBM - Boom type

4.3.4 - Slurry shield TBM

A slurry shield TBM has a full-face cutte-rhead. Confinement is achieved by pressu-rizing boring fluid inside the cutterheadchamber. Circulation of the fluid in thechamber flushes out the muck, with a regu-lar pressure being maintained by directly orindirectly controlling discharge rates.

AFTES data sheets:No. 33 – 34 – 35 – 36 – 44– 50 – 52 – 56 – 57 - 60 – 62– 63 – 69 – 76 – Cairo –Sydney

▼

▼

CutterheadShieldAir bubbleWatertight bulkheadAirlock to cutterhead chamber

Tailskin articulation (option)

Thrust ramSegment erectorTailskin seal

Cutterhead chamberAgitator (option)Slurry supply line

Slurry return linePhoto 4.3.4 - Cairo metro

▼

▼

➀ ➁ ➂ ➃ ➄ ➆⑥

➇ ➈ ➉ 11➄

➀➁➂➃➄⑥

➆➇➈➉11

➀➁➂➃➄

➆➇➈

➉11

12

13

⑥

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• 145 •

4.3.5 - Earth pressure balancemachine

An earth pressure balance machine (EPBM)has a full-face cutterhead. Confinement isachieved by pressurizing the excavatedmaterial in the cutterhead chamber. Muckis extracted from the chamber continuously

or intermittently by a pressure-reliefdischarge system that takes it from theconfinement pressure to the ambient pres-sure in the tunnel.

EPBMs can also operate in open mode orwith compressed-air confinement if spe-cially equipped.

AFTES data sheets: No. 45 – 46 - 47 – 48 –49 – 55 – 59 – 61 – 72 – 73 – 74* - 77 to 85

*TBMs also working with compressed-airconfinement

CutterheadShieldCutterhead chamberAirtightThrust ram

Articulation (option)

Tailskin sealAirlock to cutterheau chamberSegment erector

Screw conveyorMuck transfer conveyor

▼

▼

Photo 4.3.5 - CaluireTunnel, Lyons (France)

4.3.6 - Mixed-face shield TBM

Mixed-face shield TBMs have full-face cut-terheads and can work in closed or openmode and with different confinement tech-niques.

Changeover from one work mode to ano-ther requires mechanical intervention tochange the machine configuration.

Different means of muck extraction areused for each work mode.

There are three main categories ofmachine:

• Machines capable of working in openmode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with earth pressurebalance confinement provided by a screwconveyor;

• Machines capable of working in openmode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with slurry confinementprovided by means of a hydraulic muckingout system (after isolation of the beltconveyor);

• Machines capable of providing earthpressure balance and slurry confinement.

TBMs of this type are generally restricted tolarge-diameter bores because of the spacerequired for the special equipment requi-red for each confinement method.

AFTES data sheets: A86 Ouest (Socatop),Madrid metro packages 2 & 4, KCR 320(Hong Kong)

Photo 4.3.6b - A86 Ouest tunnel (Socatop) Madrid metro

Photo 4.3.6aA86 Oues tunnel (Socatop)

➀➁➂➃➄

➆➇➈➉11

⑥

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• 146 •

5 - EVALUATION OF PARA-METERS FOR CHOICE OFMECHANIZED TUNNELLINGTECHNIQUES

5.1. GENERAL

It was felt useful to assess the degree towhich elementary parameters of all kindsaffect the decision-making process forchoosing between the different mechani-zed tunnelling techniques.

The objectives of this evaluation are:

• to rank the importance of the elementaryselection parameters, with some indicationof the basic functions concerned.

• to enable project designers envisaging amechanized tunnelling solution to checkthat all the factors affecting the choice havebeen examined.

• to enable contractors taking on construc-tion of a project for which mechanized tun-nelling is envisaged to check that they arein possession of all the relevant informationin order to validate the solution chosen.

This evaluation is presented in the form oftwo tables (Tables 1 and 2).

Table 1 (§ 5.2.) indicates the degree towhich each of the elementary selectionparameters affects each of the basic func-tions of mechanized tunnelling techniques(all techniques combined).

Table 2 (§ 5.3) indicates the degree to which

each of the elementary selection parame-ters affects each individual mechanizedtunnelling technique.

These evaluation tables are complemen-ted by comments in the appendix.

The list of parameters is based on thatdrawn up by AFTES recommendationswork group No. 7 in its very useful docu-ment "Choix des paramètres et essais géo-techniques utiles à la conception, audimensionnement et à l'exécution desouvrages creusés en souterrain" (Choice ofgeotechnical parameters and tests of rele-vance to the design and construction ofunderground works). This initial list hasbeen complemented by factors other thangeotechnical ones.

Basic function SUPPORT OPPOSITION TOEXCAVATION

MUCKING OUT,Elementary

Frontal PeriphericalHYDROSTATIC EXTRACTION,

parameters PRESSURE TRANSPORTSTOCKPILING

A B C D E

1. NATURAL CONTRAINTS 2 2 SO 1 0

2. PHYSICAL PARAMETERS 2.1 Identification 2 1 2 2 12.2 Global appreciation of quality 2 2 0 1 02.3 Discontinuities 2 2 2 1 02.4 Alterability 1 1 SO 1 12.5 Water chemistry 1 0 SO 0 1

3. MECHANICAL PARAMETERS3.1 Strength Soft ground 2 2 SO 1 0

Hard rock 1 1 SO 2 03.2 Deformability 2 2 SO 0 03.3 Liquefaction potential 0 0 0 0 0

4. HYDROGEOLOGICAL PARAMETERS 2 2 2 1 0

5. OTHER PARAMETERS5.1 Abrasiveness - Hardness 0 0 0 2 15.2 Propensity to stick 0 0 0 2 25.3 Ground/machine friction 0 1 0 0 05.4 Présence of gas 0 0 0 0 0

6. PROJECT CHARACTERISTICS6.1 Dimensions, shape 2 2 2 1 26.2 Vertical alignment 0 0 0 0 26.3 Horizontal alignment 0 0 0 0 16.4 Environment

6.4.1 Sensitivity to settlement 2 2 2 0 06.4.2 Sensitivity to disturbance and work constraints 0 0 0 0 2

6.5 Anomalies in ground6.5.1 Heterogeneity of ground in tunnel section 1 1 0 2 06.5.2 Natural/artificial obstacles 0 0 0 1 06.5.3 Voids 2 2 2 0 0

2 : Decisive 1 : Has effect 0: No effect SO: Not applicable

See comments on this table in Appendix 1

5.2 - EVALUATION OF THE EFFECT OF ELEMENTARY SELECTION PARAMETERS ON THEBASIC FUNCTIONS OF MECHANIZED TUNNELLING TECHNIQUES

Table 1

AFTES


1. N

ATU

RA

L C

ON

TRA

INTS

0

22

22

21

21

1

2. P

HY

SIC

AL

PAR

AM

ETER

S 2.

1 Id

entif

icat

ion

22

22

22

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AFTES



• 148 •

6 - SPECIFIC FEATURES OFTHE DIFFERENT TUNNELLINGTECHNIQUES

6.1 - MACHINES PROVI-DING NO IMMEDIATE SUP-PORT

6.1.1 - Specific features of boom-type tunnelling machines

a) GeneralBoom-type tunnelling machines are gene-rally suited to highly cohesive soils and softrock. They consist of an excavating arm orboom mounted on a self-propelling chas-sis. There is no direct relationship betweenthe machine and the shape of the tunnel tobe driven; the tunnel cross-sections exca-vated can be varied and variable. The facecan be accessed directly at all times. Sincethese machines react directly against thetunnel floor, the floor must have a certainbearing capacity.

b) ExcavationThe arms or booms of these machines aregenerally fitted with a cutting or millinghead which excavates the face in a series ofsweeps. These machines are called road-headers. The maximum thrust on the road-header cutterhead is directly related to themass of the machine. The cutters workeither transversally (perpendicular to theboom) or in-line (axially, about the boomaxis). In most cases the spoil falling from theface is gathered by a loading apron fittedto the front of the machine and transportedto the back of the machine by beltconveyor. This excavation method gene-rates a lot of dust which has to be control-led (extraction, water spray, filtering, etc.).

In some cases the cutterhead can be repla-ced by a backhoe bucket, ripper, or hydrau-lic impact breaker.

c) Support and opposition to hydrosta-tic pressure There is no tunnel support associated withthis type of machine. It must be accompa-nied by a support method consistent withthe shape of the tunnel and the groundconditions encountered (steel ribs, rock-bolts, shotcrete, etc.).

This type of machine cannot oppose hydro-static pressure, so accompanying measures(ground improvement, groundwater lowe-ring, etc.) may be necessary.

d) Mucking outMucking out can be associated with thiskind of machine or handled separately. Itcan be done directly from the face.

6.1.2 - Specific features of Hardrock TBMs

a) GeneralThe thrust at the cutterhead is reacted toone or two rows of radial thrust pads or grip-pers which take purchase directly on thetunnel walls. As with shield TBMs, a trailingbackup behind the machine carries all theequipment it needs to operate and theassociated logistics. Forward probe drillingequipment is generally fitted to this type ofTBM. The face can be accessed by retrac-ting the cutterhead from the face when theTBM is stopped.

The machine advances sequentially (bore,regrip, bore again).

b) ExcavationThese full-face TBMs generally have arotary cutterhead dressed with differentcutters (disc cutters, drag bits, etc.). Muckis generally removed by a series of scrapersand a bucket chain which delivers it onto aconveyor transferring it to the back of themachine. Water spray is generally requiredat the face both to keep dust down and tolimit the temperature rise of the cutters.

c) Support and opposition to hydrosta-tic pressureTunnel support is independent of themachine (steel ribs, rockbolts, shotcrete,etc.) but can be erected by auxiliary equip-ment mounted on the beam and/or bac-kup. If support is erected from the mainbeam, it must take account of TBM move-ment and the gripper advance stroke. Thecutterhead is not generally designed tohold up the face. A canopy or full can issometimes provided to protect operatorsfrom falling blocks.

This kind of TBM cannot oppose hydrosta-tic pressure. Accompanying measures(groundwater lowering, drainage, groundimprovement, etc.) are required if theexpected pressures or inflows are high.

d) Mucking out Mucking out is generally done with wagonsor by belt conveyor. It is directly linked tothe TBM advance cycle.

6.1.3. Specific features of tun-nel reaming machines

a) GeneralTunnel reaming machines work in much thesame way as Hard rock TBMs, except that

the cutterhead is pulled rather thanpushed. This is done by a traction unit withgrippers in a pilot bore. As with all main-beam and shield machines, the cutterheadis rotated by a series of hydraulic or electricmotors. The tunnel can be reamed in asingle pass with a single cutterhead or inseveral passes with cutterheads of increa-sing diameter.

b) ExcavationSee Chapter 6.1.2 § b) (Hard rock TBM).

c) Support and opposition to hydrosta-tic pressure The support in the pilot bore must be des-tructible (glass-fibre rockbolts) or remo-vable (steel ribs) so that the cutterhead isnot damaged. The final support is inde-pendent of the reaming machine, but canbe erected from its backup.

For details on opposition to the hydrosta-tic pressure, see Chapter 6.1.2 § c (Hardrock TBM).

d) Mucking outSee Chapter 6.1.2.§ d) (Hard rock TBM).

6.2 - SPECIFIC FEATURES OFMACHINES PROVIDINGIMMEDIATE PERIPHERALSUPPORT

6.2.1 - Specific features of open-face gripper shield TBMs

a) GeneralAn open-face gripper shield TBM is thesame as a Hard rock TBM except that it hasa cylindrical shield.

The thrust of the cutterhead is reactedagainst the tunnel walls by means of radialpads (or grippers) taking purchase throughopenings in the shield or immediatelybehind it. As with other TBM types, a bac-kup trailing behind the TBM carries all theequipment it needs to operate, togetherwith the associated logistics.

The TBM does not thrust against the tunnellining or support.

b) ExcavationSee Chapter 6.1.2 § b) (Hard rock TBM).

c) Support and opposition to hydrosta-tic pressure The TBM provides immediate passive per-ipheral support. It also protects workersfrom the risk of falling blocks. If permanenttunnel support is required, it consists eitherof segments (installed by an erector on theTBM) or of support erected independently.

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• 149 •

This type of machine cannot oppose hydro-static pressure, so accompanying measures(ground improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terrain.

d) Mucking outSee Chapter 6.1.2 § d) (Hard rock TBM).

6.2.2 - Specific features of open-face shield TBMs

a) GeneralAn open-face shield segmental TBM haseither a full-face cutterhead or an excava-ting arm like those of the different boom-type tunnelling machines. The TBM isthrust forward by rams reacting longitudi-nally against the tunnel lining erectedbehind it.

b) ExcavationTBM advance is generally sequential:

1) boring under thrust from longitudinalrams reacting against the tunnel lining

2) retraction of thrust rams and erection ofnew ring of lining.

c) Support and opposition to hydrosta-tic pressureThe TBM provides passive peripheral sup-port and also protects workers from the riskof falling blocks.

The tunnel face must be self-supporting.Even a full-face cutterhead can only hold upthe face under exceptional conditions (e.g.limitation of collapse when the TBM is stop-ped).

Temporary or final lining is erected behindthe TBM by an erector mounted on it. It isagainst this lining that the rams thrust topush the machine forward.

This type of machine cannot oppose hydro-static pressure, so accompanying measures(ground improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terrain.

d) Mucking outMuck is generally removed by mine cars orbelt conveyors. Mucking out is directly lin-ked to the TBM advance cycle.

6.2.3 - Specific features of doubleshield TBMs

Double shield TBMs combine radial pur-chase by means of grippers with longitudi-nal purchase by means of thrust rams reac-ting against the lining. A telescopic sectionat the centre of the TBM makes it possiblefor excavation to continue while lining seg-ments are being erected.

Excavation proceeds as follows: with therear section of the TBM secured by the grip-pers, the front section thrusts against it bymeans of the main rams between the twosections, and tunnels forward. A ring of seg-mental lining segments is erected at thesame time. The grippers are then releasedand the longitudinal rams thrust against thetunnel lining to shove the rear section for-ward. The rear section regrips and the cycleis repeated.

6.3 - SPECIFIC FEATURES OFTBMS PROVIDING IMMEDIA-TE FRONTAL AND PERIPHE-RAL SUPPORT

6.3.1 - Specific features of mecha-nical-support shield TBMs

a) GeneralMechanical-support shield TBMs ensurethe stability of the excavation by retainingexcavated material ahead of the cutte-rhead. This is done by partially closinggates on openings in the head.

b) ExcavationThe face is excavated by a full-face cutte-rhead.

c) Support and opposition to hydrosta-tic pressure Real-time adjustment of the openings inthe cutterhead holds spoil against the face.

Frontal support is achieved by holdingspoil against the face (in front of the cutte-rhead).

The shield provides immediate passiveperipheral support.

The tunnel lining is erected:

• either inside the TBM tailskin, in whichcase it is sealed against the tailskin (tail seal)and back grout is injected into the annularspace around it,

• or behind the TBM tailskin (expandedlining, segments with pea-gravel backfilland grout).

This type of machine cannot oppose hydro-static pressure as a rule, so accompanyingmeasures (ground improvement, ground-water lowering, etc.) may be necessarywhen working in water-bearing or unstableterrain.

d) Mucking outMucking out is generally by means of minecars or belt conveyors.

6.3.2 - Specific features of com-pressed-air TBMs

a) GeneralWith compressed-air TBMs, only pressuri-zation of the air in the cutter chamberopposes the hydrostatic pressure at theface.

Compressed-air confinement pressure ispractically uniform over the full height ofthe face. On the other hand, the pressurediagram for thrust due to water and groundat the face is trapezoidal. This means thereare differences in the balancing of pres-sures at the face. The solution generallyadopted involves compressing the air tobalance the water pressure at the lowestpoint of the face. The greater the diameter,the greater the resulting pressure differen-tial; for this reason the use of compressed-air confinement in large-diameter tunnelsmust be studied very attentively.

Compressed-air TBMs are generally usedwith moderate hydrostatic pressures (lessthan 0.1 MPa).

b) ExcavationThe face can be excavated by a variety ofequipment (from diggers to full-face cutte-rheads dressed with an array of tools). In thecase of rotating cutterheads, the size of thespoil discharged is controlled by the ope-nings in the cutterheadla roue.

Muck can be extracted from the face by ascrew conveyor (low hydrostatic pressure)or by an enclosed conveyor with an airlock.

c) Support and opposition to hydrosta-tic pressureMechanical immediate support of the tun-nel face and walls excavation is provided bythe cutterhead and shield respectively.

The hydrostatic pressure in the ground isopposed by compressed air.

d) Mucking outMuck is generally removed by conveyor orby wheeled vehicles (trains, trucks, etc.).

6.3.3 - Specific features of slurryshield TBMs

a) GeneralThe principle of slurry shield TBM opera-tion is that the tunnel excavation is held upby means of a pressurized slurry in the cut-terhead. The slurry entrains spoil which isremoved through the slurry return line.

The tunnel lining is erected inside the TBMtailskin where a special seal (tailskin seal)prevents leakage.

Back grout is injected behind the lining asthe TBM advances.

AFTES



• 150 •

b) ExcavationThe face is excavated by a full-face cutte-rhead dressed with an array of cutter tools.Openings in the cutterhead (plus possiblya crusher upline of the first slurry return linesuction pump) control the size of spoilremoved before it reaches the pumps.

c) Support and opposition to hydrosta-tic pressureFrontal and peripheral support of the tun-nel excavation are the same, i.e. by meansof the slurry pressure generated by thehydraulic mucking out system.

In permeable ground (K ≥ 5 x 10-5 m/s) it ispossible to pressurize the chamber by crea-ting a ‘cake’ of thixotropic slurry (bentonite,polymer, etc.), generally with relative den-sity of between 1.05 and 1.15, on a tunnelface and walls.

With such a ‘cake’ in place it is possible forworkers to enter the pressurized cutte-rhead (via an airlock).

The TBM can be converted to open mode,but the task is complex.

As for tunnel support, the hydrostatic pres-sure is withstood by forming a ‘cake’ to helpform a hydraulic gradient between thehydrostatic pressure in the ground and theslurry pressure in the cutterhead chamber.

Together with control of the stability of theexcavation and of settlement, oppositionto hydrostatic pressure is a design consi-deration for the confinement pressure; theconfinement pressure is regulated eitherby direct adjustment of the slurry supplyand return pumps or by means of an “airbubble” whose level and pressure arecontrolled by a compressor and reliefvalves. With an “air bubble” in the cutte-rhead chamber the confinement pressurecan be measured and regulated within avery narrow range of variation.

d) Mucking outMuck is removed by pumping it through thepipes connecting the TBM to the slurryseparation and recycling plant.

In most cases the muck is often treated out-side the tunnel, in a slurry separation plant.This does introduce some risks associatedwith the type of spoil to be treated (clog-ging of plant, difficulties for disposal ofresidual sludge).

The pump flowrate and the treatmentcapacity of the separation plant determineTBM progress.

6.3.4 - Specific features of earthpressure balance machines

a) General The principle of EPBM operation is that theexcavation is held up by pressurizing thespoil held in the cutterhead chamber tobalance the earth pressure exerted. Ifnecessary, the bulked spoil can be mademore plastic by injecting additives from theopenings in the cutterhead chamber, thepressure bulkhead, and the muck-extrac-tion screw conveyor. By reducing friction,the additives reduce the torque required tochurn the spoil, thus liberating more torqueto work on the face. They also help main-tain a constant confinement pressure at theface.

Muck is extracted by a screw conveyor, pos-sibly together with other pressure-reliefdevices.

The tunnel lining is erected inside the TBMtailskin, with a tailskin seal ensuring thereare no leaks. Back grout is injected behindthe lining as the TBM advances.

b) ExcavationThe tunnel is excavated by a full-face cut-terhead dressed with an array of tools. Thesize of spoil removed is controlled by ope-nings in the cutterhead which are in turndetermined by the dimensional capacity ofthe screw conveyor.

The power at the cutterhead has to be highbecause spoil is constantly churned in thecutterhead chamber.

c) Support and opposition to hydrosta-tic pressureFace support is uniform. It is obtained bymeans of the excavated spoil and additiveswhich generally maintain its relative densityat between 1 and 2. Peripheral support canbe enhanced by injecting products throughthe shield.

For manual work to proceed in the cutte-rhead chamber, it may be necessary tocreate a sealing cake at the face throughcontrolled substitution (without loss ofconfinement pressure) of the spoil in thechamber with bentonite slurry.

L’architecture de ce type de tunnelier per-met un passage rapide du mode fermé enmode ouvert.

The hydrostatic pressure is withstood byforming a plug of confined earth in thechamber and screw conveyor; the pressuregradient between the face and the spoildischarge point is balanced by pressurelosses in the extraction and pressure-reliefdevice.

Care must be take over the type and loca-tion of sensors in order to achieve propermeasurement and control of the pressurein the cutterhead chamber.

d) Mucking outAfter the muck-extraction screw conveyor,spoil is generally transported by conveyorsor by wheeled vehicles (trains, trucks).

The muck is general ly “diggable”,enabling it to be disposed of without addi-tional treatment; however, it may be neces-sary to study the biodegradability of theadditives if the disposal site is in a sensitiveenvironment.

The architecture of this type of TBM allowsfor rapid changeover from closed to openmode and vice versa.

7 - APPLICATION OFMECHANIZED TUNNELLINGTECHNIQUES

7.1 - MACHINES NOT PRO-VIDING IMMEDIATE SUP-PORT

7.1.1 - Boom-type tunnellingmachines

Boom-type units are generally suitable forhighly cohesive soils and soft rock. Theyreach their limits in soils with compressivestrength in excess of 30 to 40 MPa, whichcorresponds to class R3 to R5 in the classi-fication given in Appendix 3 (depending onthe degree of cracking or foliation). Theeffective power of these machines isdirectly related to their weight.

When these machines are used in water-bearing ground, some form of groundimprovement must be carried out before-hand to overcome the problem of signifi-cant water inflow.

When excavating clayey soils in water, thecutters of roadheaders may become clog-ged or balled; in such terrain, a specialstudy of the cutters must carried out toovercome the problem. It may be advisableto use a backhoe instead.

These techniques are particularly suitablefor excavating tunnels with short lengths ofdifferent cross-sections, or where the tun-nel is to be driven in successive headings.

The tunnel support accompanying thismethod of excavation is independent ofthe machine used. It will be adapted to theconditions encountered (ground, environ-ment, etc.) and the shape of the excavation.

7.1.2 - Hard rock TBMs

Hard rock TBMs are particularly suited totunnels of constant cross-section in rock of

AFTES



• 151 •

strength classes R1 to R4 (see rock classifi-cation in Appendix 3).

For the lower strength classes (R3b-R4), thebearing surface of the grippers is generallyincreased in order to prevent them pun-ching into the ground. If there is a risk ofalteration of the tunnel floor due to water,laying a concrete invert behind themachine will facilitate movement of thebackup. To provide short-term stabilizationof the excavation, it will be necessary tohave rapid support-erection systems thatwill be independent of but neverthelesscompatible with the TBM.

For the higher strength classes (R1-R2a), allthe boreability parameters must be takeninto account in the TBM design.

In hard and abrasive ground in particular, itis recommended that every precaution betaken to allow for cutters to be replaced inperfect safety.

A system for spraying water on the tunnelface will cool the cutters and keep dustdown. It can be complemented by dustscreens, extraction, and filters.

Hard rock TBMs are generally fitted withdestructive drilling rigs for forward probedrilling, together with drill data-loggingequipment. The probe holes are drilledwhen the TBM is not working.

The design of these machines does notallow them to support non-cohesive soils asthey advance, or to oppose hydrostaticpressure. For this reason accompanyingmeasures such as drainage and/or consoli-dation of the ground are necessary beforethe machines traverse a geological acci-dent. Consequently the TBM must beequipped to detect such features and totreat the ground ahead of the face whennecessary.

7.1.3 - Tunnel reaming machines

Tunnel reamers are suitable for excavatinglarge horizontal or incl ined tunnels(upwards of 8 m in diameter) in rock (R1 toR3, sometimes R4 and R5).

The advantages of reaming a tunnel from apilot bore are as follows:

• The ground is investigated as the pilotbore is driven

• Any low-strength ground encounteredcan be consolidated from the pilot borebefore full-diameter excavation

• The ground to be excavated is drained

• The pilot bore can be used for dewate-ring and ventilation

• Temporary support can be erected inde-pendently of the machine.

7.2 - MACHINES PROVI-DING IMMEDIATE PERIPHE-RAL SUPPORT

7.2.1 - Open-face gripper shieldTBMs

Open-face gripper shield TBMs are parti-cularly suitable for tunnelling in rock ofstrength classes between R1 and R3

The shield provides immediate support forthe tunnel and/or protects the workforcefrom falling blocks.

The shield can help get through certaingeological difficulties by avoiding the needfor support immediately behind the cutte-rhead.

Application of this technique can be limi-ted by the ability of the ground to withstandthe radial gripper thrust.

The general considerations outlined in §7.1.2 also apply here.

7.2.2 - Open-face shield TBMs

An open-face shield TBM requires full liningor support along the length of the tunnelagainst which it can thrust to advance.

Its field of application is soft rock (strengthclasses R4 and R5) and soft ground requi-ring support but in which the tunnel faceholds up.

The general considerations outlined in §7.1.2 also apply here.

This type of TBM can traverse certain typesof heterogeneity in the ground. It alsoenables the tunnel support to be industria-lized to some extent. On the other hand,the presence of the lining and shield cangive rise to difficulties when crossing obs-tacles such as geological accidents, sincethey hinder access to the face for treatmentor consolidation of the ground.

7.2.3 - Open-face double shieldTBMs

Open-face double shield TBMs combinethe advantages and disadvantages asso-ciated with radial grippers and longitudinalthrust rams pushing off tunnel lining: theyneed either a lining or ground of sufficientstrength to withstand gripper thrust.

This greater technical complexity is some-times chosen when lining is required so thatboring can proceed (with gripper purchase)while the lining ring is being erected.

7.3 - MACHINES PROVI-DING IMMEDIATE FRONTALAND PERIPHERAL SUPPORT

7.3.1 - Mechanical-support shieldTBMs

The difference between mechanical-sup-port shield TBMs and open-face shieldTBMs lies in the nature of the cutterhead.Mechanical-support TBMs have:

• openings with adjustable gates

• a peripheral seal between the cutterheadand the shield.

Face support is achieved by holding spoilahead of the cutterhead by adjusting theopenings. It does not provide ‘genuine’confinement, merely passive support of theface.

Its specific field of application is thereforein soft rock and consolidated soft groundwith little or no water pressure

7.3.2 - Compressed-air TBMs

Compressed-air TBMs are particularly sui-table for ground of low permeability with nomajor discontinuities (i.e. no risk of suddenloss of air pressure).

The ground tunnelled must necessarilyhave an impermeable layer in the overbur-den.

Compressed-air TBMs tend to be used toexcavate small-diameter tunnels.

Their use is not recommended in circum-stances where the ground at the face isheterogeneous (unstable ground in theroof which could cave in). They should beprohibited in organic soil where there is arisk of fire.

In the case of small-diameter tunnels, it maybe possible to have compressed air in all orpart of the finished tunnel.

7.3.3 - Slurry shield TBMs

Slurry shield TBMs are particularly suitablefor use in granular soil (sand, gravel, etc.)and heterogeneous soft ground, thoughthey can also be used in other terrain, evenif it includes hard-rock sections.

There might be clogging and difficultyseparating the spoil from the slurry if thereis clay in the soil.

These TBMs can be used in ground withhigh permeability (up to 10-2 m/s), but ifthere is high water pressure a special slurryhas to be used to form a watertight cake onthe excavation walls. However, their use isusually restricted to hydrostatic pressuresof a few dozen MPa.

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• 152 •

Generally speaking, good control of slurryquality and of the regularity of confinementpressure ensures that surface settlement iskept to the very minimum.

Contaminated ground (or highly aggres-sive water) may cause problems and requirespecial adaptation of the slurry mix design.

The presence of methane in the ground isnot a problem for this kind of TBM.

If the tunnel alignment runs throughcontrasting heterogeneous ground, theremay be difficulties extracting and proces-sing the spoil.

7.3.4 - Earth pressure balancemachines

EPBMs are particularly suitable for soilswhich, after churning, are likely to be of aconsistency capable of transmitting thepressure in the cutterhead chamber andforming a plug in the muck-extractionscrew conveyor (clayey soil, silt, fine clayeysand, soft chalk, marl, clayey schist).

They can handle ground of quite high per-meability (10–3 to 10-4 m/s), and are alsocapable of working in ground with occasio-nal discontinuities requiring localizedconfinement.en l’absence

In hard and abrasive ground it may benecessary to use additives or to take spe-cial measures such as installing hard-facingor wearplates on the cutterhead and screwconveyor.a vitesse de progression del’usure par

In permeable ground, maintenance in thecutterhead chamber is made complexbecause of the need to establish a water-tight cake at the face beforehand, withoutlosing confinement pressure.

8 - TECHNIQUES ACCOMPA-NYING MECHANIZED TUN-NELLING

8.1 - PRELIMINARY INVESTI-GATIONS FROM THE SURFA-CE

8.1.1 - Environmental impactassessment

At the preliminary design stage an environ-mental impact assessment should be car-ried out in order to properly assess thedimensional characteristics proposed forthe tunnel, particularly its cross-section,sectional area, and overburden.

In addition, the effect and sensitivity of sett-lement-especially in built-up areas-should

be given special attention. This is a decisivefactor in choosing the tunnelling and sup-port methods, the tunnel alignment, andthe cross-section.

The environmental impact assessmentshould be thorough, taking account of thedensity of existing works and the diversityof their behaviours.

For existing underground works, the com-patibility of the proposed tunnelling andsupport methods or the adaptations requi-red (special treatment or accompanyingmeasures) should be assessed throughspecial analysis.

8.1.2 - Ground conditions

The purpose of preliminary investigationsis not just for design of the temporary andpermanent works, but also to check the fea-sibility of the project in constructionalterms, i.e. with respect to excavation, muc-king out, and short- and long-term stability.

Design of the works involves determiningshape, geological cross-sections, the phy-sical and mechanical characteristics of theground encountered by the tunnel, and thehydrogeological context of the project as awhole.

Project feasibility is determined by thepotential reactions of the ground, includingdetails of both the formations traversedand of the terrain as a whole, with respectto the loadings generated by the works, i.e.with respect to the excavation/confine-ment method adopted.

Depending on the context and the specificrequirements of the project, the synopsis ofinvestigation results should therefore dealwith each of the topics detailed in theAFTES recommendations on the choice ofgeotechnical tests and parameters, irres-pective of the geological context (cf.: T.O.SNo. 28, 1978, re-issued 05/93 – review inprogress; and T.O.S No. 123, 1994).

If the excavation/confinement method isonly chosen at the tender stage, anddepending on the confinement methodchosen by the Contractor, additional inves-tigations may have to be carried out to vali-date the various options adopted.

8.1.3 - Resources used

Depending on the magnitude and com-plexity of the project, preliminary investi-gations - traditionally based on boreholesand borehole tests - may be extended to“large-scale” observation of the behaviourof the ground by means of test adits andshafts.

Advantage can be taken of the investiga-tion period to proceed with tests of the tun-

nelling and support methods as well as anyassociated treatments.

If there are to be forward probe investiga-tions, matching of the boring and investi-gation methods should be envisaged at thepreliminary investigation stage.

In the event of exceptional overburdenconditions and difficult access from the sur-face, directional drilling investigation(mining and/or petroleum industry tech-niques) of long distances (one kilometre ormore) along the tunnel alignment may bejustified, especially if it is associated withgeophysical investigations and appro-priate in situ testing.

8.2 - FORWARD PROBING

The concept of forward probing must beset against the risk involved. This type ofinvestigation is cumbersome and costly, forit penalizes tunnelling progress since—inthe case of full-face and shield TBMs—themachine has to be stopped during probing(with current-day technology). It shouldtherefore be used only in response to anexplicit and absolute requirement to raiseany uncertainty over the conditions to beexpected when crossing areas where sitesafety, preservation of existing works, or thedurability of the project might be at risk.

Irrespective of the methodology selected,it must give the specialists implementing itreal possibilities for avoiding difficulties byimplementing corrective action in goodtime.

The first condition that forward probingmust meet in order to achieve this objec-tive is that it give sufficiently clear andobjective information about the situationahead of the face (between 1 and 5 timesthe tunnel diameter ahead), with a leadtimeconsistent with the rate of tunnel progress.

The second condition is that in terms ofquality it must be adapted to the specificrequirements of the project (identificationof clear voids, of decompressed areas,faults, etc.). These criteria should be deter-mined jointly by the Designer, Engineer,and Contractor and should be clearly fea-tured in specifications issued to the per-sons carrying out the investigations.

During tunnelling, analysis of results isgenerally the responsibility of the investi-gations contractor, but the interpretation ofdata, in correlation with TBM advance para-meters (monitoring), should in principle bethe responsibility of the contractor opera-ting the TBM.

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8.3 - GROUND IMPROVE-MENT

Prior ground improvement is sometimesnecessary, particularly in order to cross:• singular features such as break-ins andbreakouts, including on works along theroute (shafts, stations, etc.)• discontinuities and fault zones identifiedbeforehand • permeable water-bearing ground.

If the problem areas are of limited extent,ground improvement will sometimesenable a less sophisticated - and thereforeless costly - tunnelling technique to beadopted.

Since ground improvement is long andcostly to carry out from the tunnel (espe-cially when the alignment is below thewater table), the work is generally donefrom the surface (in the case of shallowoverburden).

These days, however, there is a trend forTBMs to be fitted with the basic equipment(such as penetrations in the bulkheadand/or cans) enabling ground improve-ment to be carried out from the machineshould water-bearing ground not compa-tible with the tunnelling technique adop-ted be encountered unexpectedly. This canalso be the case when local conditions pro-hibit treatment from the surface.

When confinement-type TBMs are used,geological and hydrogeological condi-tions often require special treatment forbreak-ins and breakouts. This point shouldnot be overlooked, neither at the prelimi-nary design stage (surface occupation,ground and network investigations, worksschedule) nor during the constructionphase, for this is one of the most difficultphases of tunnelling.

Special attention should be given to thecompatibility of ground treatment with thetunnelling process (foaming, reaction withslurry and additives, etc.)

The most commonly used ground impro-vement techniques are:• permeation-grouted plug of bentonite-cement and/or gel• diaphragm-wall box• total replacement of soil by bentonite-cement• jet-grouted plug

8.4 - GUIDANCE

Guidance of full-face TBMs is vital. The per-formance of the guidance system usedmust be consistent with the type of TBM

and lining, and with the purpose of the tun-nel.

The development of shield TBMs incorpo-rating simultaneous erection of precastsegmental lining has led to the design ofhighly sophisticated guidance systems,because with tunnel lining it is impossibleto remedy deviation from the correctcourse. Consequently, the operator (orautomatic operating system) must be givenreal-time information on the position of theface and the tunnelling trend relative to thetheoretical alignment. However, whenconsidering the construction tolerance itmust be remembered that the lining will notnecessarily be centred in the excavation,and that it may be subject to its own defor-mation (offset, ovalization, etc.). The gene-rally accepted tolerance is an envelope for-ming a circle about 20 cm larger in diameterthan the theoretical diameter.

Whatever the degree of sophistication ofthe guidance system, it is necessary to:

• reliably transfer a traverse into the tunneland close it as soon as possible (breakoutinto shaft, station, etc.)

• carry out regular and precise topogra-phical checks of the position of the TBMand of the tunnel

• know how quickly (speed and distance)the TBM can react to modifications to thetrajectory it is on.

8.5 - ADDITIVES

a) General Mechanized tunnelling techniques makeuse of products of widely differing physicaland chemical natures that can all be label-led “conditioning fluids and slurries”.Before any chemical additives are used, itshould be checked that they present nodanger for the environment (they will bemixed in with the muck and could presentproblems when it is disposed of) or for theworkforce (particularly during pressurizedwork in the cutterhead chamber where thetemperature can be high).

b) WaterWater will be present in the ground invarying quantities, and will determine thesoil's consistency, as can be seen from dif-ferent geotechnical characterization testsor concrete tests (Atterberg limits for clayeysoils and slump or Abrams cone test for gra-nular soils). It can be used alone, with clay(bentonite), with hydrosoluble polymers, orwith surfactants to form a conditioning fluid(slurry or foam).

c) AirBy itself air cannot be considered to be aboring additive in the same way as water orother products; its conditioning action isvery limited. When used in pressurizedTBMs - if the permeability of the grounddoes not prohibit it - air helps support thetunnel. As a compressible fluid, air helpsdamp confinement-pressure variations inthe techniques using slurry machines with“air bubbles” and EPB machines with foam.As a constituent of foam, air also helps flui-dify and reduce the density of muck, andhelps regulate the confinement pressure inthe earth-pressure-balance process.

d) BentoniteOf the many kinds of clay, bentonite is mostcertainly the best-known drilling or boringmud. It has extremely high swell, due to thepresence of its specific clayey constituent,montmorillonite, which gives it very inter-esting colloidal and sealing qualities.

In the slurry-confinement technique, therheological qualities of bentonite (thixo-tropy) make it possible to establish a confi-nement pressure in a permeable mediumby sealing the walls of the excavationthrough pressurized filtration of the slurryinto the soil (formation of a sealing cakethrough a combination of permeation andmembrane), and to transport muck bypumping.

Bentonite slurry can also be used with anEPB machine, to improve the consistencyof the granular material excavated (homo-genization, plastification, lubrication, etc.).

In permeable ground, the EPB techniqueuses the same principle of cake formationbefore work is carried out in the pressurizedcutterhead chamber.

e) PolymersOf the multitude of products on the market,only hydrosoluble or dispersible com-pounds are of any interest as tunnellingadditives. Most of these are well knownproducts in the drilling industry whoserheological properties have been enhan-ced to meet the specific requirements ofmechanized tunnelling.

These modifications essentially concernenhanced viscosifying power in order tobetter homogenize coarse granular mate-rials, and enhanced lubrifying qualities inorder to limit sticking or clogging of the cut-terhead and mucking out system whenboring in certain types of soil.

Polymers may be of three types:

• natural polymers (starch, guar gum, xan-than gum, etc.)

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• modified natural or semi-synthetic poly-mers (CMC [carboxymethylcellulose], etc.)

• synthetic polymers (polyacrylamides,polyacrylates, etc.)

f) Foams (surfactants)Foams are two-phase systems (a gas phaseand a liquid phase containing the foamingagent) which are characterized physicallyby their expansion factor (volume occupiedby the air in the foam relative to the volumeof liquid).

Foams are easy to use. They are similar toaerated slurries, combining the advan-tages of a gas (compressibility, practicallyzero density, etc.) and of a slurry (fluidifica-tion, lubrication, pore filling, etc.). With EPBmachines they are used to facilitate confi-nement and sometimes excavation andmucking out as well.

8.6 - DATA LOGGING

The acquisition and restitution of TBM ope-rating parameters is undoubtedly the big-gest factor in the technical progress ofmechanized tunnelling in the last ten years.

It makes for objective analysis of the ope-rating status and dysfunctions of themachine and its auxiliaries.

The status of the machine at any given timeis short-lived and changes rapidly. Withoutdata logging, this gave rise to varied andoften erroneous interpretations in the past.

Logging gives a “true” technical analysisthat is indispensable for smooth operationon projects in difficult or sensitive sites.

Data logging also provides a basis for com-puterized control of TBM operation andautomation of its functions (guidance, muc-king out, confinement pressure regulation,etc.).

Data logging also provides an exact recordof operating statuses and their durations(cf. recommendation on analysis of TBMoperating time and coefficients, TOS No.148, July 98).

They also constitute operating feedbackthat can be used to optimize TBM use.

8.7 - TUNNEL LINING ANDBACKGROUTING

8.7.1 - General

In the case of segmental TBMs, the liningand its backgrouting are inseparable fromthe operation of the machine.

Without any transition and in perfectlycontrolled fashion, the lining and back-grout must balance the hydrostatic pres-sure, support the excavation peripherally,and limit surface settlement.

Because of their interfaces with themachine, they must be designed in paralleland in interdependence with the TBM.

8.7.2 - Lining

The lining behind a shield TBM generallyconsists of reinforced concrete segments.Sometimes (for small-diameter tunnels)cast-iron segments are used. More excep-tionally the lining is slipcast behind a slidingform.

Reinforced concrete segments are by farthe most commonly used. The other tech-niques are gradually being phased out foreconomic or technical reasons.

The segments are erected by a machineincorporated into the TBM which gripsthem either mechanically or by means ofsuction.

The following AFTES recommendationsexamine tunnel lining:

• Recommandations sur les revêtementspréfabriqués des tunnels circulaires au tun-nelier (Recommendations on precast liningof bored circular tunnels), TOS No. 86

• Recommandation sur les joints d’étan-chéité entre voussoirs (Recommendationson gaskets between lining segments), TOSNo. 116, March/April 1993

• Recommandations “pour la conceptionet le dimensionnement des revêtements envoussoirs préfabriqués en béton armé ins-tal lés à l ’arr ière d’un tunnel ier”(Recommendations “on the design of pre-cast reinforced concrete lining segmentsinstalled behind TBMs”) drawn up byAFTES work group No. 18, published inTOS No. 147, May/June 1998.

8.7.3 - Backgrouting

This section concerns only mechanizedtunnelling techniques involving segmentallining.

Experience shows the extreme importanceof controlling the grouting pressure andfilling of the annular space in order tocontrol and restrict settlement at the sur-face and to securely block the lining ring inposition, given that in the short term thelining is subject to its selfweight, TBMthrust, and possibly flotational forces.

Grouting should be carried out conti-nuously, with constant control, as themachine advances, before a gap appearsbehind the TBM tailskin.

In the early days backfilling consisted ofeither pea gravel or fast-setting or fast-har-dening cement slurry or mortar that wasinjected intermittently through holes in thesegments.

Since management of the grout and its har-dening between mixing and injection is avery complex task, there has been aconstant trend to drop cement-based pro-ducts in favour of products with retardedset (pozzolanic reaction) and low compres-sive strength. Such products are injectedcontinuously and directly into the annularspace directly behind the TBM tailskin bymeans of grout pipes routed through thetailskin.

9 - HEALTH AND SAFETYMechanization of tunnelling has very sub-stantially improved the health and safetyconditions of tunnellers. However, it hasalso induced or magnified certain specificrisks that should not be overlooked. Theseinclude:• risk of electrical fire or spread of fire tohydraulic oils• risk of electrocution• risks during or subsequent to compres-sed-air work • risks inherent to handling of heavy parts(lining segments)• mechanical risks• risk of falls and slips (walkways, ladders,etc.)

9.1 - DESIGN OF TUNNEL-LING MACHINES

Tunnelling machines are work items thatmust comply with the regulations of theMachinery Directive of the EuropeanCommittee for Standardization (CEN).

These regulations are aimed primarily atdesigners—with a view to obtaining equip-ment compliant with the Directive—butalso at users.

The standards give the minimum safetymeasures and requirements for the specificrisks associated with the different kinds oftunnelling machines. Primarily they applyto machines manufactured after the date ofapproval of the European standard.• At the time of writing only one standardhad been homologated:- NF EN 815 “Safety of unshielded tunnelboring machines and rodless shaft boringmachines for rock” (December 1996)• Three are in the approval process:- Pr EN 12111 “Tunnelling machines -

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Roadheaders, continuous miners andimpact rippers – Safety requirements”

- Pr EN 12336 “Tunnelling machines –Shield machines, horizontal thrust boringmachines, lining erection equipment -Safety requirements ”

- Pr EN 12110 “Tunnelling machines –Airlocks – Safety requirements ”

9.2 - USE OF TUNNELLINGMACHINES

Machine excavation of underground worksinvolves specific risks linked essentially to

atmospheric pollution (gas, toxic gases,noise, temperature), flammable gases andother flammable products in the ground,electrical equipment (low and high vol-tage), hydraulic equipment (power orcontrol devices), and compressed-air work(work in large-diameter cutterhead cham-bers under compressed air, pressurizationof whole sections of small-diameter tun-nels).

A variety of bodies dealing with safety onpublic works projects have drawn up textsand recommendations on safety. In France,these include OPPBTP, CRAM, and INRS,for example.

All their requirements should be incorpo-rated into the General Co-Ordination Planand Health and Safety Plan at the start ofworks.

APPENDICES 1, 2, 3, AND 41. Comments on Table No. 1 in Chapter 52. Comments on Table No. 2 in Chapter 53. Ground classification table4. Mechanized tunnelling project datasheets

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APPENDIX 1

COMMENTS ON TABLE NO.1 IN CHAPTER 5.

1 - Natural constraints

Support (columns A and B)With knowledge of natural constraints:• a choice can be made from among thetunnelling technique groups (from boom-type units to confinement-type TBMs)

• relaxation of stresses can be managed(from simple deformation-convergence tofailure).

2 - PHYSICAL PARAMETERS

2.1 - Identification

❑ Face support (column A)

With knowledge of physical parameters:

• the support method can be assessed,and the tunnelling technique group chosen

• the requirement for face support can beassessed.

❑ Peripheral support (column B)

With knowledge of physical parameters therequirement for peripheral support aroundthe machine can be assessed.

❑ Opposition to hydrostatic pressure(column C)

With knowledge of physical parametersand of grain and block sizes, the permea-bility of the terrain can be assessed, leadingto a proposal for the way hydrostatic pres-sure could be controlled.

❑ Excavation (column D)

Of the parameters concerned, grain andblock size are decisive for assessing theexcavation method (design of cutterhead,cutters, etc.).

2.2 - Global appreciationof quality

❑ Support (columns A and B)

Global appreciation of quality provides

additional information for identificationthat concerns only the sample. This datadefines more global information at thescale of the soil horizon concerned.

2.3 - Discontinuities


This data concerns rock and coherent softground. With knowledge of discontinuitiesa choice can be made among the tunneltechnique groups (from boom-type units toconfinement-type TBMs).

❑ Opposition to hydrostatic pressure(column C)

With knowledge of discontinuities thecrack permeability and water pressure tobe taken into account for the project can beassessed. This enables the type of tech-nique to be chosen.

❑ Excavation (column D)

In conjunction with knowledge of blocksizes, knowledge of discontinuities (nature,size, and frequency) can be decisive ormerely have an effect on the excavationmethod to be adopted.

3 - MECHANICAL PARAME-TERS

3.1 - Strength


With knowledge of mechanical parametersa preliminary choice can be made fromamong the tunnelling technique groups(from boom-type units to confinement-type TBMs).

❑ Excavation (hard rock)(column D)

Knowledge of mechanical parameters isparticularly important for defining thearchitecture of the machine and helpsdetermine its technical characteristics(torque, power, etc.) and the choice of cut-ting tools.

3.2 - Deformability


With knowledge of deformability therelaxation of stresses can be assessed andtaken into account (from simple deforma-tion or convergence to failure).

3.3 - Liquefaction potential

❑ Support and mucking out (columns A, Band E)

Knowledge of the liquefaction potentialhas an effect in seismic zones and in caseswhere the technique chosen might set upvibrations in the ground (blasting, etc.).

4 - HYDROGEOLOGICALPARAMETERS❑ Support, opposition to hydrostatic pres-sure, and excavation (Columns A, B, C andD)

Knowledge of these parameters is decisivein appreciating control of the stability of thetunnel, both at the face and peripherally,and therefore in choosing the method fromthe various tunnelling techniques. In thecase of tunnels beneath deep overburdenit is not easy to obtain these parameters.They should be estimated with the greatestcare and analyzed with caution.

5 - OTHER PARAMETERS❑ Excavation and mucking out (Columns Dand E)

The parameters of abrasiveness and hard-ness are decisive or have an effect in appre-ciation of the excavation and mucking-outmethods to be used. These parametersshould be studied in parallel with themechanical parameters (strength in parti-cular).

6 - PROJECT CHARACTERIS-TICSNo comment.

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Comments on Table No. 1in Chapter 5

1 - NATURAL CONSTRAINTSThe stress pattern in the ground is veryimportant in deep tunnels or in cases ofhigh anisotropy. If the rate of stress releaseis high, with Hard rock TBMs, shield TBMs,and reaming machines, it may cause:

• jamming of the machine (jamming of thecutterhead or body)

• rockburst at the face or in tunnel walls,roof, or invert.

With slurry-shield TBMs or EPBMs it is rarefor the natural stress pattern to be decisivein the choice of machine type since they aregenerally used for shallow tunnels.

2 - PHYSICAL PARAMETERS

2.1 - Identification

The type of ground plays a decisive role inthe choice and design of a shield TBM.Consequently the parameters characteri-zing the identification of the ground mustbe examined carefully when choosing theexcavation/support method.

The most important of the identificationparameters are plasticity and - for hardness,clogging potential, and abrasiveness -mineralogy which are particularly decisivein the selection of shield TBM components.

Chemical analysis of the soil can be deci-sive in the case of confinement-type shieldTBMs because of the effect soil might haveon the additives used in these techniques.

2.2 - Global appreciationof quality

Global appreciation of quality results fromcombining parameters which are easy tomeasure in the laboratory or in situ (bore-hole logs, RQD) and visual approaches.

Weathered zones and zones with contras-ting hardness can cause specific difficultiesfor the different tunnelling techniques, e.g.face instability, insufficient strength forgrippers, confinement difficulties.

The degree of weathering of rock has aneffect but is not generally decisive for slurryshields and EPBMs. In all cases it has aneffect for cutterhead design.

2.3 - Discontinuities

For rock, knowledge of the situation regar-ding discontinuities is decisive (orientationand density of the network), for it will affectthe choice of the tunnelling and supporttechnique as well as the tunnelling speed.

With open-face Hard rock TBMs andshields and mechanical-support TBMs,attention should be given to the risk of jam-ming of the machine induced by the den-sity of a network of discontinuities whichcould quite rapidly lead to doubtful stabi-lity of the terrain. The existence of uncon-solidated infilling material can aggravatethe resulting instability.

The presence of major discontinuities canhave a major effect on the choice of tun-nelling technique.

Slurry shields and compressed-air TBMsare generally more sensitive to the pre-sence of discontinuities than EPBMs. Ifthere are major discontinuities (high den-sity of fracturation), the compressed-airconfinement TBM may have to be elimina-ted from the possible range.

In general the overall permeability of theterrain should be examined in conjunctionwith its discontinuities before selecting thetype of confinement.

2.4 - Alterability

Alterability characteristics concern terrainthat is sensitive to water. Alterability datashould be obtained at the identificationstage.

Special attention should be given to alte-rability when mechanized tunnelling is totake place in water-sensitive ground such ascertain molasses, marls, certain schists,active clays, indurated clays, etc.

Alterability has an effect on confinement-type TBMs; it can result in changes beingmade to the design of the machine and thechoice of additives.

2.5 - Water chemistry

Problems related to the aggressivity or thedegree of pollution of water may arise invery specific cases and have to be dealt withregardless of the tunnelling principlesadopted.

With confinement-type TBMs this parame-ter may be decisive because of its effect onthe quality of the slurry or additives.

3 - MECHANICAL PARAME-TERS

3.1 - Strength

In the case of rock, the essential mechani-cal criteria are the compressive and tensilestrength of the terrain, for they conditionthe efficacy of excavation.

In soft ground, the essential criteria arecohesion and the angle of friction, for theycondition the hold-up of the face and of theexcavation as a whole.

The very high strengths of some rocksexclude the use of boom-type tunnellingmachines (unless they are highly cracked).Gripper-type tunnel boring and reamingmachines are very sensitive to low-strengthground and may require special adaptationof the gripper pads. For main-beam andshield TBMs alike, the machine architec-ture, the installed power at the cutterhead,and the choice and design of cutting toolsand cutterhead are conditioned by thestrength of the ground.

If there is any chance of tunnel bearingcapacity being insufficient, special treat-ment may be necessary for the machine toadvance.

3.2 - Deformability

Deformability of the terrain may cause jam-ming of the TBM, especially in the event ofconvergence resulting from high stresses(see paragraph 1, “Natural constraints”).

In the case of tunnel reamers and open-faceor mechanical-support TBMs, this criterionaffects the appreciation of the risks of cut-terhead or shield jamming.

In the case of excessively deformable mate-rial, the design of TBM gripper pads willhave to be studied carefully. The deforma-bility of the surrounding ground also affectsTBM guidance. If the tunnel lining is erec-ted to the rear of the tailskin, attentionshould be paid to the risk of deferred defor-mation.

In ground that swells in contact with water,the resulting difficulties for advancing themachine are comparable for both slurryshield and EPB machines, in so far as theswelling is due to the diffusion and absorp-tion of water within the decompressedground around the tunnel. Compressed-airTBMs are less sensitive to this phenome-non.

APPENDIX 2

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3.3 - Liquefaction potential

Not applicable, except if there is a risk ofearthquake or if the ground is particularlysensitive (saturated sand, etc.).

4 - HYDROGEOLOGICALPARAMETERSThe purpose of examining the hydrogeo-logical parameters of the terrain is toensure that it will remain stable in the shortterm. The presence of high water pressuresand/or potential inflow rates entrainingmaterial will prohibit the use of boom-typemachines and open-face or mechanical-support machines unless accompanyingmeasures such as ground improvement,groundwater lowering, etc. are carried out.

Water pressure is also decisive when geo-logical accidents (e.g. mylonite) have to becrossed, irrespective of whether or not theyare infilled with loose soil.

Ground permeability and hydrostatic pres-sure are decisive for TBMs using compres-sed-air, slurry, or EPB confinement.Compressed-air machines may even berejected because of these factors, and theyare particularly decisive for EPBMs whenthere are likely to be sudden variations inpermeability. For slurry shield TBMs, theeffects of these parameters are attenuatedby the fact that a fluid is used for muckingout.

5 - OTHER PARAMETERS

5.1 - Abrasiveness -Hardness

Excessively high abrasiveness and hard-ness make it impossible or uneconomic touse boom-type tunnelling machines.

Abrasiveness and hardness can be decisivewith respect to tool wear, the structure ofthe cutterhead, and extraction systems(screw conveyor, slurry pipes, etc.) .However, the expected wear can be coun-tered by using boring and/or extractionadditives and/or protection or reinforce-ment on sensitive parts.

5.2 - Sticking - Clogging

When the potential the material to be exca-vated has to stick or clog is known, the cut-ters of boom-type units, tunnel reamers, orshield TBMs can be adapted or use of anadditive envisaged.

This parameter alone cannot exclude atype of shield TBM; it is therefore not deci-s ive for face-confinement shields.However, the trend for the ground to stickmust be examined with respect to thedevelopment of additives (foam, admix-tures, etc.) and the design of the equipmentfor churning and mixing the sticky spoil(agitators, jetting, etc.).

The transport of muck by trains and/orconveyors is particularly sensitive to thisparameter.

5.3 - Ground/machine fric-tion

For shield TBMs the problem of ground fric-tion on the shield can be critical in groundwhere convergence is high.

Where there is a real risk of TBM jamming(convergence, swelling, dilitancy, etc.) thisparameter has a particularly importanteffect on the design of the shield.

The lubrication provided by their bentoniteslurry makes slurry shield TBMs less sus-ceptible to the problems ofground/machine friction.

5.4 - Presence of gas

The presence of gas in the ground candetermine the equipment fitted to themachine.

6 - PROJECT CHARACTERIS-TICS

6.1 - Dimensions and sec-tions

Boom-type units can excavate tunnels ofany shape and sectional area. Shield TBMs,main-beam machines, and reamers canexcavate tunnels of constant shape only.The sectional area that can be excavated isrelated to the stability of the face.

The sectional area of tunnels is decisive forlarge-diameter EPBMs (power required atthe cutterhead).

The length of the project can have an effecton slurry shield TBMs (pumping distance).

6.2 - Vertical alignment

The limits imposed on tunnelling machinesby the vertical profile are generally those ofthe associated logistics. Main-beam tunnelboring and reaming machines can be adap-

ted to bore inclined tunnels, but the requi-rement for special equipment takes thembeyond the scope of these recommenda-tions.

With boom-type units and open-face ormechanical-support TBMs, water inflowcan cause problems in downgrade drives.

6.3 - Horizontal alignment

❑ The use of boom-type units imposes noparticular constraints.

❑ The use of main-beam tunnel boring andreaming machines and of shield TBMs islimited to certain radii of curvature (evenwith articulations on the machines).

❑ With shield TBMs the al ignmentafter/before break-ins and breakoutsshould be straight for at least twice thelength of the shield (since it is impossible tosteer the machine when it is on its slidecradle).

6.4 - Environment

6.4.1 - Sensitivity to settlement

Since boom-type units, tunnel reamers,Hard rock TBMs, and open-face shieldTBMs do not generally provide any imme-diate support, they can engender settle-ment at the surface. Settlement will be par-ticularly decisive in urban or sensitive zones(transits below routes of communicationsuch as railways, pipelines, etc.).

Sensitivity to settlement is generally deci-sive for all TBM types and can lead to exclu-sion of a given technique.

Open-face or mechanical-support shieldTBMs are not suitable for use in very defor-mable ground. If the tunnel lining is erec-ted to the rear of the tailskin, attentionshould be paid to the risk of deferred defor-mation of the surrounding ground.

With confinement-type TBMs, control ofsettlement is closely linked to that of confi-nement pressure.

With compressed-air shields the risk of sett-lement lies in loss of air (sudden or gradual).

With slurry shield TBMs the risk lies in thequality of the cake and in the regulation ofthe pressure. In relation to this, the “airbubble” confinement pressure regulationsystem performs particularly well.

With EPBMs the risk lies in less preciseregulation of the confinement pressure.Moreover, the annular space around theshield is not properly confined, unlessarrangements are made to inject slurrythrough the cans.

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6.4.2 - Sensitivity to disturbanceand work constraints

Slurry shield machines require a large areaat the surface for the slurry separation plant.This constraint can have an effect on thechoice of TBM type or even be decisive inintensively built-up zones.

The additives introduced into the cutte-rhead chamber of shield TBMs (bentonite,polymer, surfactant, etc.) may implyconstraints on disposal of spoil.

6.5 - Anomalies in ground

6.5.1 - Ground/accident heteroge-neity

Mixed hard rock/soft ground generallyimplies face-stability and gripping pro-blems for tunnelling techniques with no

confinement, and also introduces a risk ofcaving-in of the roof where the ground issoftest.

6.5.2 - Natural and artificial obs-tacles

For “open” techniques it is essential to beable to detect geological accidents. Forconfinement techniques attention shouldbe paid to the presence of obstacles, whe-ther natural or artificial. Obstacles can havean effect on the choice of machine, depen-ding on the difficulties encountered inovercoming the obstacle and the need towork from the cutterhead chamber.

Compressed-air work necessary for detec-ting and dealing with obstacles requiresreplacement of the products in the cutte-rhead chamber (products depending onthe confinement method) with compressedair.

The work required for replacing them is:

❑ faster and simpler with a compressed-airTBM (in principle)

❑ easy with a slurry shield TBM

❑ longer and more difficult with an earthpressure balance machine (extraction ofthe earth and substitution with slurry toform a sealing film, followed by removal ofthe bulk of the slurry and replacement withcompressed air).

6.5.3 - Voids

Depending on their size, the presence ofvoids can engender very substantial devia-tion from the design trajectory, especiallyvertically. They can also be a source of dis-turbance to the confinement pressure, par-ticularly with compressed-air or slurryshield TBMs.

APPENDIX 3

Ground classification table (cf. GT7)

Catégory Description Examples RC (MPa)R1 Very strong rock Strong quartzite and basalt > 200

R2a Very strong granite, porphyry, very strongStrong rock sandstone and limestone 200 à 120

R2b Granite, very resistant or slightly dolomitized sandstone and 120 à 60limestone, marble, dolomite, compact conglomerate

Ordinary sandstone, siliceous schist or R3aModerately strong rock schistose sandstone, gneiss

60 à 40

R3b Clayey schist, moderately strong sandstone and limestone, 40 à 20compact marl, poorly cemented conglomerate

Schist or soft or highly cracked limestone, gypsum, 20 à 6R4 Low strength rock highly cracked or marly sandstone, puddingstone, chalk

R5 a Very low strength rock and Sandy or clayey marls, marly sand, gypsumconsolidated cohesive soils or weathered chalk

6 à 0,5

R5b Gravelly alluvium, normally consolidated clayey sand < 0,5

R6a Plastic or slightly consolidated soils Weathered marl, plain clay, clayey sand, fine loam

R6b Peat, silt and little consolidated mud, fine non-cohesive sand

AFTES



• 160 •

APPENDIX 4Mechanized tunnelling data sheets (up to 31/12/99).

1 Echaillon D 68 1972-1973 4362 5.80 Gneiss, flysch, limestone2 La Coche D 77 1972-1973 5287 3.00 Limestone, sandstone, breccia3 CERN SPS H 64 1973-1974 6551 4.80 Molasse4 RER Châtelet-Gare de Lyon C 64 1973-1975 5100 7.00 Limestone5 Belledonne D 64 1974-1978 9998 5.88 Schist, sedimentary granite6 Bramefarine D 67 1975-1977 3700 8.10 Limestone, schist7 Lyons metro - Crémaillère C 64 1976 220 3.08 Gneiss, granite8 Galerie du Bourget C 67 1976-1978 4845 6 m2 Limestone, molasse9 Monaco - Service tunnel H 64 1977 913 3.30 Limestone, marne10 Grand Maison - Eau Dolle D 64 1978 839 3.60 Gneiss, schist, dolomite11 Western Oslofjord G 77 1978-1984 10500 3.00 Slate, limestone, igneous rock12 Brevon D 66 1979-1981 4150 3.00 Limestone, dolomite, other calcareous rock (malm)13 Grand Maison (penstocks and service shaft) D 75 1979-1982 5466 3.60 Gneiss, schist14 Marignan aqueduct F 66 1979-1980 480 5.52 m2 Limestone15 Super Bissorte D 73 1980-1981 2975 3.60 Schist, sandstone16 Pouget D 66 1980-1981 3999 5.05 Gneiss17 Grand Maison - Vaujany D 75 1981-1983 5400 7.70 Liptinite, gneiss, amphibolite18 Vieux Pré D 68 1981-1982 1257 2.90 Sandstone, conglomeratee19 Haute Romanche Tunnel D 73 1981-1982 2860 3.60 Limestone, schist, crystalline sandstone20 Cilaos F 80 1982-1984 5701 3.00 Basalt, tuff21 Monaco - tunnel No. 6 A 66 1982 183 5.05 Limestone, dolomite22 Ferrières D 79 1982-1985 4313 5.90 Schist, gneiss23 Durolle D 79 1983-1984 2139 3.40 Granite, quartz, microgranite24 Montfermy D 80 1983-1985 5040 3.55 Gneiss, anatexite, granite25 CERN LEP (machines 1 and 2) H 82 1985-1986 14680 4.50 Molasse26 CERN LEP (machine 3) H 82 1985-1987 4706 4.50 Molasse27 Val d'Isère funicular B 97 1986 1689 4.20 Limestone, dolomite, cargneule (cellular dolomite)28 Calavon and Luberon F 97 1987-1988 2787 3.40 Limestone29 Takamaka II D 101 1985-1987 4803 3.20 Basalt, tuff, agglomerates30 Oued Lakhdar D 101 1986-1987 6394 4.56 and 4.80 Limestone, sandstone, marl31 Paluel nuclear power plant E 105 1980-1982 2427 5.00 Chalk32 Penly nuclear power plant E 105 1986-1988 2510 5.15 Clay33 Lyons river crossing - metro line D C 106 1984-1987 2 x 1230 6.50 Recent alluvium and granitic sand34 Lille metro, line 1b - Package 8 C 106 1986-1987 1000 7.65 White chalk and flint35 Lille metro, Line 1b - Package 3 C 106 1986-1988 3259 7.70 Clayey sand and silt36 Villejust tunnel B 106 1986-1988 4805 + 4798 9.25 Fontainebleau sand Bade/Theelen (2 machines)37 Bordeaux: Cauderan-Naujac G 106 1986-1988 1936 5.02 Sand, marl and limestone 38 Caracas metro: package PS 01 C 107 1986-1987 2 x 1564 5.70 Silty-sandy alluvium, gravel, and clay39 Caracas metro: package CP 03 C 107 1987 2 x 2131 5.70 Weathered micaschist and silty sand40 Caracas metro: package CP 04 C 107 1987-1988 2 x 714 5.70 Micaschist41 Singapore metro: package 106 C 107 1985-1986 2600 5.89 Sandstone, marl and clay42 Bordeaux: "boulevards" main sewers Ø3800 G 113 1989-1990 1461 4.36 Karstic limestone and alluvium43 Bordeaux:Avenue de la Libération Ø2200 G 113 1988-1989 918 2.95 Karstic limestone and alluvium44 St Maur-Créteil, section 2 G 113 1988-1990 1530 3.35 Old alluvium and boulders45 Crosne-Villeneuve St Georges G 113 1988-1990 911 2.58 Weathered marl and indurated limestone46 Channel Tunnel T1 B 114 1988-1990 15618 5.77 Blue chalk47 Channel Tunnel T2-T3 B 114 1988-1991 20009 + 18860 8.78 Blue chalk48 Channel Tunnel T4 B 114 1988-1989 3162 5.61 Grey and white chalk49 Channel Tunnel T5-T6 B 114 1988 - 1990 2 x 3265 8.64 Grey and white chalk50 Sèvres - Achères: Package 3 G 121 1989 - 1991 3550 4.05 Coarse limestone, sand, upper Landenian clay

(fausses glaises), plastic clay, Montian marl, chalk51 Sèvres - Achères: Packages 4 and 5 G 121 1988 - 1990 3312 4.8 Sand, upper Landenian clay (fausses glaises),

plastic clay, Montian marl and limestone, chalk52 Créteil - Vitry G 124 1990 - 1991 2065 3.35 Alluvium and made ground

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53 Orly Val: Package 2 C 124 1989 - 1990 1160 7.64 Marl with beds of gypsum54 Bordeaux Caudéran -

Naujac Rue de la Liberté G 126 1991 150 3.84 Karstic limestone55 Bordeaux Amont Taudin G 126 1991 500 2.88 Alluvium and karstic limestone56 Rouen "Métrobus" C 126 1993 800 8.33 Black clay, middle Albian sand and Gault clay57 Toulouse metro: Package 3 C 131 1989 - 1991 3150 7.65 Clayey-sandy molasse and beds of sandstone58 Toulouse metro: Packages 4 and 5 C 131 1990 - 1991 1587 + 1487 5.6 Molasse59 Lille metro: Line 2 Package 1 C 132 1992 - 1994 5043 7.65 Flanders clay60 Lille metro: Line 2 Section b C 132 1992 - 1993 1473 7.65 Chalk, clay, and sandy chalk61 St Maur:VL3c main sewer G 133 1992 - 1994 1350 3.5 Very heterogenous plastic clay, sand, coarse

limestone, and upper Landenian clay (fausses glaises)62 Lyons metro: Line D

Vaise - Gorge de Loup C 133 1993 - 1995 2 x 875 6.27 Sand, gravel, and clayey silt63 METEOR Line 14 C 142 1993 - 1995 4500 8.61 Sand, limestone, marl,upper Lutetian

marl/limestone (caillasses)64 RER Line D Chatelet / Gare de Lyon C 142 1993 - 1994 2 x 1600 7.08 Coarse limestone65 Cleuson Dixence Package D Inclined shaft D 142 1994 - 1996 2300 4.77 Limestone, quartzites, schist, sandstone66 Cleuson Dixence Inclined shaft D 142 1994 - 1996 400 4.4 Limestone, schist, sandstone67 Cleuson Dixence Package B

Headrace tunnel D 153 1994 - 1996 7400 5.6 Schist and gneiss68 Cleuson Dixence Package C

Headrace tunnel D 152 1994 - 1996 7400 5.8 Schist, micachist, gneiss, and quartzite69 EOLE B 146 1993 - 1996 2 x 1700 7.4 Sands, marl and 'caillasse' marl/limestone,

sandstone and limestone70 South-east plateau outfall sewer (EPSE) G 146 1994 - 1997 3925 4.42 Molasse sand, moraine, alluvium71 Cadiz: Galerie Guadiaro Majaceite F 148 1995 - 1997 12200 4.88 Limestone, consolidated clay72 Lille metro Line 2 Package 2 C 148 1995 - 1997 3962 7.68 Flanders clay73 North Lyons bypass,

Caluire tunnel, North tube A 150 1994 - 1996 3252 11.02 Gneiss, molasse, sands and conglomerate74 North Lyons bypass, Caluire tunnel,

South tube A 150 1997 - 1998 3250 11.02 Gneiss, molasse, sand, and conglomerate75 Storebaelt rail tunnels B 150 1990 - 1995 14824 8.78 Clay and marl76 Strasbourg tram line C 150 1992 - 1993 1198 8.3 Sands and graviers77 Thiais main sewer Package 1 G 154 1987 - 1989 4404 2.84 Marl and clay78 Antony urban area main sewer G 154 1989 1483 2.84 Alluvium, limestone, marl79 Fresnes transit G 154 1991 280 2.84 Marl and alluvium80 Main sewer beneath CD 67 road in Antony G 154 1991 670 2.84 Marl81 Duplication of main sewer,

Rue de la Barre in Enghien G 154 1992 - 1993 807 2.84 Sand, marly limestone, marl82 Bièvre interceptor G 154 1993 1000 2.84 Marl and alluvium83 Duplication of main sewer,

Ru des Espérances - 8th tranche G 156 1993 - 1994 1387 2.54 Limestone, sand84 Duplication of main sewer,

Ru des Espérances - 9th tranche G 156 1995 - 1996 1200 2.54 Coarse limestone, marly limestone85 Duplication of main sewer,

Ru des Espérances - 10th tranche G 156 1996 - 1997 469 2.54 Marly limestone

(APPENDIX 4)

*AITES classification of project typesA road tunnels - B rail tunnels - C metros - D hydropower tunnels -E nuclear and fossil-fuel power plant tunnels - F water tunnels - G sewers-H service tunnels - I access inclines - J underground storage facilities - K mines -

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• 162 •

APPENDIX 4Mechanized tunnelling data sheets (up to 31/12/99).

1 Echaillon D 68 1972-1973 4362 5.80 Gneiss, flysch, limestone Wirth2 La Coche D 77 1972-1973 5287 3.00 Limestone, sandstone, breccia Robbins3 CERN SPS H 64 1973-1974 6551 4.80 Molasse Robbins4 RER Châtelet-Gare de Lyon C 64 1973-1975 5100 7.00 Limestone Robbins5 Belledonne D 64 1974-1978 9998 5.88 Schist, sedimentary granite Wirth6 Bramefarine D 67 1975-1977 3700 8.10 Limestone, schist Robbins7 Lyons metro - Crémaillère C 64 1976 220 3.08 Gneiss, granite Wirth8 Galerie du Bourget C 67 1976-1978 4845 6 m2 Limestone, molasse Alpine9 Monaco - Service tunnel H 64 1977 913 3.30 Limestone, marne Robbins10 Grand Maison - Eau Dolle D 64 1978 839 3.60 Gneiss, schist, dolomite Wirth11 Western Oslofjord G 77 1978-1984 10500 3.00 Slate, limestone, igneous rock Bouygues 12 Brevon D 66 1979-1981 4150 3.00 Limestone, dolomite, other calcareous rock (malm) Bouygues13 Grand Maison (penstocks and service shaft) D 75 1979-1982 5466 3.60 Gneiss, schist Wirth 14 Marignan aqueduct F 66 1979-1980 480 5.52 m2 Limestone Alpine15 Super Bissorte D 73 1980-1981 2975 3.60 Schist, sandstone Wirth16 Pouget D 66 1980-1981 3999 5.05 Gneiss Wirth17 Grand Maison - Vaujany D 75 1981-1983 5400 7.70 Liptinite, gneiss, amphibolite Robbins18 Vieux Pré D 68 1981-1982 1257 2.90 Sandstone, conglomeratee Bouygues19 Haute Romanche Tunnel D 73 1981-1982 2860 3.60 Limestone, schist, crystalline sandstone Wirth20 Cilaos F 80 1982-1984 5701 3.00 Basalt, tuff Wirth21 Monaco - tunnel No. 6 A 66 1982 183 5.05 Limestone, dolomite Wirth22 Ferrières D 79 1982-1985 4313 5.90 Schist, gneiss Wirth23 Durolle D 79 1983-1984 2139 3.40 Granite, quartz, microgranite Wirth24 Montfermy D 80 1983-1985 5040 3.55 Gneiss, anatexite, granite Robbins25 CERN LEP (machines 1 and 2) H 82 1985-1986 14680 4.50 Molasse Wirth 26 CERN LEP (machine 3) H 82 1985-1987 4706 4.50 Molasse Wirth27 Val d'Isère funicular B 97 1986 1689 4.20 Limestone, dolomite, cargneule (cellular dolomite) Wirth28 Calavon and Luberon F 97 1987-1988 2787 3.40 Limestone Wirth29 Takamaka II D 101 1985-1987 4803 3.20 Basalt, tuff, agglomerates Bouygues30 Oued Lakhdar D 101 1986-1987 6394 4.56 and 4.80 Limestone, sandstone, marl Wirth31 Paluel nuclear power plant E 105 1980-1982 2427 5.00 Chalk Zokor32 Penly nuclear power plant E 105 1986-1988 2510 5.15 Clay Zokor 33 Lyons river crossing - metro line D C 106 1984-1987 2 x 1230 6.50 Recent alluvium and granitic sand Bade34 Lille metro, line 1b - Package 8 C 106 1986-1987 1000 7.65 White chalk and flint FCB/Kawasaki35 Lille metro, Line 1b - Package 3 C 106 1986-1988 3259 7.70 Clayey sand and silt Herrenknecht36 Villejust tunnel B 106 1986-1988 4805 + 4798 9.25 Fontainebleau sand Bade/Theelen (2 machines)37 Bordeaux: Cauderan-Naujac G 106 1986-1988 1936 5.02 Sand, marl and limestone Bessac38 Caracas metro: package PS 01 C 107 1986-1987 2 x 1564 5.70 Silty-sandy alluvium, gravel, and clay Lovat 39 Caracas metro: package CP 03 C 107 1987 2 x 2131 5.70 Weathered micaschist and silty sand Lovat 40 Caracas metro: package CP 04 C 107 1987-1988 2 x 714 5.70 Micaschist Lovat 41 Singapore metro: package 106 C 107 1985-1986 2600 5.89 Sandstone, marl and clay Grosvenor42 Bordeaux: "boulevards" main sewers Ø3800 G 113 1989-1990 1461 4.36 Karstic limestone and alluvium Bessac43 Bordeaux:Avenue de la Libération Ø2200 G 113 1988-1989 918 2.95 Karstic limestone and alluvium Bessac44 St Maur-Créteil, section 2 G 113 1988-1990 1530 3.35 Old alluvium and boulders FCB45 Crosne-Villeneuve St Georges G 113 1988-1990 911 2.58 Weathered marl and indurated limestone Howden46 Channel Tunnel T1 B 114 1988-1990 15618 5.77 Blue chalk Robbins47 Channel Tunnel T2-T3 B 114 1988-1991 20009+18860 8.78 Blue chalk Robbins/Kawasaki48 Channel Tunnel T4 B 114 1988-1989 3162 5.61 Grey and white chalk Mitsubishi49 Channel Tunnel T5-T6 B 114 1988 - 1990 2 x 3265 8.64 Grey and white chalk Mitsubishi50 Sèvres - Achères: Package 3 G 121 1989 - 1991 3550 4.05 Coarse limestone, sand, upper Landenian clay

(fausses glaises), plastic clay, Montian marl, chalk Herrenknecht51 Sèvres - Achères: Packages 4 and 5 G 121 1988 - 1990 3312 4.8 Sand, upper Landenian clay (fausses glaises),

plastic clay, Montian marl and limestone, chalk Lovat52 Créteil - Vitry G 124 1990 - 1991 2065 3.35 Alluvium and made ground FCB

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53 Orly Val: Package 2 C 124 1989 - 1990 1160 7.64 Marl with beds of gypsum Howden54 Bordeaux Caudéran -

Naujac Rue de la Liberté G 126 1991 150 3.84 Karstic limestone Bessac55 Bordeaux Amont Taudin G 126 1991 500 2.88 Alluvium and karstic limestone Howden56 Rouen "Métrobus" C 126 1993 800 8.33 Black clay, middle Albian sand and Gault clay Herrenknecht57 Toulouse metro: Package 3 C 131 1989 - 1991 3150 7.65 Clayey-sandy molasse and beds of sandstone FCB / Kawasaki58 Toulouse metro: Packages 4 and 5 C 131 1990 - 1991 1587+1487 5.6 Molasse Lovat59 Lille metro: Line 2 Package 1 C 132 1992 - 1994 5043 7.65 Flanders clay FCB60 Lille metro: Line 2 Section b C 132 1992 - 1993 1473 7.65 Chalk, clay, and sandy chalk FCB61 St Maur:VL3c main sewer G 133 1992 - 1994 1350 3.5 Very heterogenous plastic clay, sand, coarse limestone,

and upper Landenian clay (fausses glaises) Herrenknecht62 Lyons metro: Line D

Vaise - Gorge de Loup C 133 1993 - 1995 2 x 875 6.27 Sand, gravel, and clayey silt Herrenknecht63 METEOR Line 14 C 142 1993 - 1995 4500 8.61 Sand, limestone, marl,upper Lutetian

marl/limestone (caillasses) HDW64 RER Line D Chatelet / Gare de Lyon C 142 1993 - 1994 2 x 1600 7.08 Coarse limestone Lovat65 Cleuson Dixence Package D Inclined shaft D 142 1994 - 1996 2300 4.77 Limestone, quartzites, schist, sandstone Robbins66 Cleuson Dixence Inclined shaft D 142 1994 - 1996 400 4.4 Limestone, schist, sandstone Lovat67 Cleuson Dixence Package B

Headrace tunnel D 153 1994 - 1996 7400 5.6 Schist and gneiss Wirth68 Cleuson Dixence Package C

Headrace tunnel D 152 1994 - 1996 7400 5.8 Schist, micachist, gneiss, and quartzite Robbins69 EOLE B 146 1993 - 1996 2 x 1700 7.4 Sands, marl and 'caillasse' marl/limestone,

sandstone and limestone Voest Alpine70 South-east plateau outfall sewer (EPSE) G 146 1994 - 1997 3925 4.42 Molasse sand, moraine, alluvium NFM71 Cadiz: Galerie Guadiaro Majaceite F 148 1995 - 1997 12200 4.88 Limestone, consolidated clay NFM/MHI72 Lille metro Line 2 Package 2 C 148 1995 - 1997 3962 7.68 Flanders clay FCB73 North Lyons bypass,

Caluire tunnel, North tube A 150 1994 - 1996 3252 11.02 Gneiss, molasse, sands and conglomerate NFM74 North Lyons bypass, Caluire tunnel,

South tube A 150 1997 - 1998 3250 11.02 Gneiss, molasse, sand, and conglomerate NFM75 Storebaelt rail tunnels B 150 1990 - 1995 14824 8.78 Clay and marl Howden76 Strasbourg tram line C 150 1992 - 1993 1198 8.3 Sands and graviers Herrenknecht77 Thiais main sewer Package 1 G 154 1987 - 1989 4404 2.84 Marl and clay Lovat78 Antony urban area main sewer G 154 1989 1483 2.84 Alluvium, limestone, marl Lovat79 Fresnes transit G 154 1991 280 2.84 Marl and alluvium Lovat80 Main sewer beneath CD 67 road in Antony G 154 1991 670 2.84 Marl Lovat81 Duplication of main sewer,

Rue de la Barre in Enghien G 154 1992 - 1993 807 2.84 Sand, marly limestone, marl Lovat82 Bièvre interceptor G 154 1993 1000 2.84 Marl and alluvium Lovat83 Duplication of main sewer,

Ru des Espérances - 8th tranche G 156 1993 - 1994 1387 2.54 Limestone, sand Lovat84 Duplication of main sewer,

Ru des Espérances - 9th tranche G 156 1995 - 1996 1200 2.54 Coarse limestone, marly limestone Lovat85 Duplication of main sewer,

Ru des Espérances - 10th tranche G 156 1996 - 1997 469 2.54 Marly limestone Lovat

(APPENDIX 4)

*AITES classification of project typesA road tunnels - B rail tunnels - C metros - D hydropower tunnels -E nuclear and fossil-fuel power plant tunnels - F water tunnels - G sewers-H service tunnels - I access inclines - J underground storage facilities - K mines -

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AFTES

Notes :

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