Specification for tunnelling

85 Pages·2000·23.469 MB·English

Closed-Face Tunnelling Machines
and Ground Stability
A guideline for best practice
British Tunnelling Society
in association with the
Institution of Civil Engineers
PublishedbyThomasTelfordPublishing,ThomasTelfordLtd,
1HeronQuay,LondonE144JD.
URL:www.thomastelford.com
DistributorsforThomasTelfordbooksare
USA:ASCEPress,1801AlexanderBellDrive,Reston,VA20191-4400,USA
Japan:MaruzenCo.Ltd,BookDepartment,3–10Nihonbashi2-chome,Chuo-ku,Tokyo103
Australia:DABooksandJournals,648WhitehorseRoad,Mitcham3132,Victoria
Firstpublished2005
AlsoavailablefromThomasTelfordBooks
SpecificationforTunnelling.BritishTunnellingSociety.ISBN0727728652
TunnelLiningDesignGuide.BritishTunnellingSociety.ISBN0727729861
BuildingResponsetoTunnelling.CIRIAandImperialCollege.ISBN0727731177
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
ISBN:0727733869
#TheBritishTunnellingSociety,theInstitutionofCivilEngineersandCrown2005
Allrights,includingtranslation,reserved.ExceptaspermittedbytheCopyright,Designsand
PatentsAct1988,nopartofthispublicationmaybereproduced,storedinaretrievalsystem
or transmitted in any form or by any means, electronic, mechanical, photocopying or
otherwise,withoutthepriorwrittenpermissionofthePublishingDirector,ThomasTelford
Publishing,ThomasTelfordLtd,1HeronQuay,LondonE144JD.
Thisbookispublishedontheunderstandingthattheauthorsaresolelyresponsibleforthe
statementsmadeandopinionsexpressedinitandthatitspublicationdoesnotnecessarily
imply that such statements and/or opinions are or reflect the views or opinions of the
publishers.Whileeveryefforthasbeenmadetoensurethatthestatementsmadeandthe
opinions expressed in this publication provide a safe and accurate guide, no liability or
responsibilitycanbeacceptedinthisrespectbytheauthorsorpublishers.
TypesetbyAcademicþTechnical,Bristol
PrintedandboundinGreatBritainbyMPGBooks,Bodmin
Front cover illustration: Eight closed-face TBMs of the slurry and earth pressurebalance
(EPB)typeswereusedbetweenAugust2002andFebruary2004toexcavateatotal40km
(20 route km) of 8m outer diameter twin running tunnels under the River Thames from
Kentandbeneaththe suburbsofeast LondonfortheChannelTunnelRail Linkproject.
Thetypesofmachinesusedwere:
KawasakiEPBMonContract220
WirthEPBMonContract240
LovatEPBMonContract250
HerrenknechtSTMonContract320
Plan of theChannel Tunnel RailLink Section 2 alignment
Contents
Acknowledgements vii
Preface ix
List of illustrations xi
1 Introduction 1
2 Technology of closed-face tunnelling machines 2
2.1 Machine types 2
2.2 Cutterhead and cutters 4
2.3 Spoil conditioning 4
2.4 Dealing with boulders 6
2.5 Screw conveyor design 6
2.6 TBM articulation 6
2.7 Seal systems 6
2.8 Tail seals 6
2.9 Control systems 6
2.10 Improved general reliability 7
2.11 Future development 7
3 Choosing between earth pressure balance machines
(EPBMs) and slurry tunnelling machines (STMs) 9
3.1 Review of ground types 9
3.2 Selection criteria 11
4 Incident data 15
4.1 Introduction 15
4.2 Analysis 15
4.3 Summary 16
5 Hazards associated with urban tunnelling 19
5.1 Historical land use issues 19
5.2 Physical constraints on the works 19
5.3 Ground movements and environmental disturbance due
to tunnelling 20
5.4 Management of hazards associated with urban tunnelling 21
6 Use of risk management 22
6.1 Identification 22
6.2 Assessment 22
6.3 Risk response 22
6.4 Embed and review 23
7 Review of site investigation methods 24
7.1 Site investigation generally 24
7.2 Relevant risks 24
7.3 Site investigation techniques 25
8 Tunnelling process – construction 29
8.1 Personnel 29
8.2 Management process 29
8.3 Excavation 30
8.4 Spoil conditioning 30
8.5 Operating pressures 34
8.6 Torque and thrust 37
8.7 Filling the shield body annulus 39
8.8 Ring build 39
8.9 Annular grouting 41
9 Tunnelling process – monitoring, recording and reviewing 44
9.1 Trained and skilled personnel 44
9.2 TBM operating parameters 44
9.3 Excavation spoil records 46
9.4 Ring build records 49
9.5 Annular grouting records 49
9.6 Ground and structure monitoring 49
9.7 Monitoring review and reconciliation 50
9.8 Overall monitoring and control 50
10 Conclusions and recommendations 54
Appendix A Examples of engineering, technical hazards
associated with urban tunnelling 58
Appendix B Potential roles of geophysics in closed-face
urban tunnelling 60
Appendix C Glossary of terms 67
Appendix D Risk register sheet 70
References 73
Bibliography 74
Index 75
Acknowledgements
ThisguidelinewaspreparedbytheClosed-FaceWorkingGroupofthe
British Tunnelling Society.
Members of the Closed-Face Working Group
Alastair Biggart (Chairman), Independent Tunnelling Consultant
Keith Bowers, Ove Arup & Partners, Rail Link Engineering
David Court, Edmund Nuttall (Deputy Chairman) (Chairman BTS)
HadynDavies,UnionRailways(North)Ltd,ChannelTunnelRailLink
Bill Grose, Ove Arup & Partners
Myles O’Reilly, Independent Consultant
David Sharrocks, Costain Skanska Bachy Joint Venture
Gordon Torp-Petersen, Cross London Rail Links (Crossrail)
Researchers
Rodney Craig, Independent Consultant – Worldwide incidents
Vicki Hope, Ove Arup & Partners – Geophysical methods
Peer Reviewers
Lars Babendererde, Independent Consultant, Germany
Brian Garrod, Hatch Mott MacDonald, Canada
Vittorio Guglielmetti, Geodata, Italy
Richard Lewis, Independent TBM Consultant, UK
Colin Mackenzie, Independent Consultant, UK
Masaru Matsuzaki, Nishimatsu, Japan
Toshi Nomoto, Nishimatsu, Japan
Kevin Province, Allianz Global Risks, UK
Roy Slocombe, Herrenknecht, UK
George Williamson, Traylor Bros, USA
Contributors to the Report
Mike Black, Cross London Rail Links (Crossrail), UK
Stephen Coffey, TBM Consultant, UK (sadly deceased before
publication)
Gordon Ince, TBM Consultant, UK
Professor Robert Mair, Cambridge University, UK
Marc Fooks, Cross London Rail Links (Crossrail), UK
Edited for the Closed-Face Working Group by
Shani Wallis, Freelance Technical Journalist, UK
TheClosed-FaceWorkingGroupisgratefultoQAPhotos,UK;LOVAT
Inc.,Canada;Herrenknecht,Germany;andChannelTunnelRailLink,
UKforsupplyofphotographsandillustrationsandpermissiontouse
theminthispublication.
Preface
This report is produced in response to a series of incidents of ground
instabilityandcollapsethathaveoccurredonrecenttunnellingprojects
insuburbanandcitycentreenvironmentsonwhichclosed-facetunnel-
ling machines were used. In the UK these include eventsthat occurred
on the recently excavated tunnels for the Channel Tunnel Rail Link
(CTRL) Project under the suburbs of east London and in particular
to the event reported and referred to in the media and the technical
trade pressas the ‘Lavender Street incident’ thatoccurredin February
2003. It also relates to events that occurred on UK tunnel projects in
Portsmouth in May 2000 and in Hull in November 1999, and draws
ontheexperienceofsimilarincidentsofgroundinstabilityandcollapse
that have occurredon closed-face tunnelling machine projects in other
countries during the past five years.
Compared to the many thousands of recorded kilometres of tunnels
excavated in the world using closed-face tunnel boring machines since
theirintroductionsome30yearsago,theincidenceofgroundinstability
and collapse is small. Nevertheless, events on tunnelling projects that
come to theattentionofthe mediaand the generalpublic arejustifiable
causesforconcern.Forthetunnellingindustry,everyincidentisanevent
from which lessons are learned and guidelines for best practice are
refined.
The purpose of this report is to examine the potential for ground
instability or collapse when using closed-face tunnelling machines, to
investigate the efficacy of various ground investigation techniques in
urban areas, and to recommend management and operational
guidelines to further minimise the risk when tunnelling beneath
highly developed urban and city centre areas. This report does not
aim to set out the details of particular incidents: there are official
enquiry reports or media articles describing these events already in
the public domain.
Tunnelling is a vital element in the full spectrum of civil engineering
options available to city planners and developers of sustainable public
infrastructure. The risks involved are also acknowledged by those
engaged in the industry. The refining of best practice, together with
rapidly advancing technological development, is a continuous process.
If anyone has any comments concerning the content of this report
thesecanbedirectedtotheClosed-FaceWorkingGroupoftheBritish
Tunnelling Society via the Secretary of the British Tunnelling Society
(BTS) at the Institution of Civil Engineers, One Great George Street,
LondonSW1P3AA,UKorviatheSociety’[email protected].
List of illustrations
page
FrontCover Eightclosed-faceTBMsoftheslurryandearthpressurebalance(EPB)types frontcover
wereusedbetweenAugust2002andFebruary2004toexcavateatotal40km
(20routekm)of8mouterdiametertwinrunningtunnelsundertheRiver
ThamesfromKentandbeneaththesuburbsofeastLondonfortheChannel
TunnelRailLinkProject
Routemap PlanoftheChannelTunnelRailLinkSection2alignment
Figure2.1 IllustrationofanSTM(slurrytunnellingmachine)system 3
Figure2.2 IllustrationofanEPBM(earthpressurebalancemachine)system 3
Figures2.3,2.4, Cutterheadsofthefourtypesofclosed-facetunnellingmachinesusedrecently
2.5and2.6 toexcavatetheChannelTunnelRailLinkSection2tunnels
Figure2.3 KawasakiEPBMusedonContract220 4
Figure2.4 WirthEPBMusedonContract240 5
Figure2.5 LovatEPBMusedonContract250 5
Figure2.6 HerrenknechtSTMusedundertheRiverThamesonContract320 5
Figure3.1 Graphofsoilparticledistributioncurves 10
Figure3.2 STMin-boundandout-boundslurrypipelines 13
Figure3.3 Muckskipsbeingloaded 13
Figure3.4 Continuousconveyormuckhaulagesystemattachedtoright-handwallofthe 14
tunnelandrunningthefulllengthofthedrive
Figure4.1 Sealedtunneleyesfortwinrunningtunnelsinthetemporaryworks 17
constructionofaworkingaccessshaftthroughwhichaclosed-facetunnelling
machinewilllaunchwithoutallowinganylossofgroundasthemachine
breaksout
Figure5.1 SurfaceinstallationofanSTMslurrytreatmentplant 20
Figure7.1 Aboreholedrillingriginthefieldtakinggeologicalsiteinvestigationcores 26
Figure8.1 TBMoperator’sscreenillustratinginjectionofspoilconditioningagent 31
Figure8.2 FactorytestofconditioningagentbeinginjectedthroughportsontheEPBM 32
cutterhead
Figure8.3 Stackingconveyorstransferringspoilontoasitestockpilereadyforonward 34
finaldisposal
Figure8.4 ExampleofaTBMoperator’sdrivescreendisplayingvitaldataofmonitored 35
TBMfunctions
Figure8.5 LongitudinalsectionofanSTManditstrailingback-uponwhichislocated 38
theoperator’scontrolcabin,theannulargroutinjectionstation,ventilation
ducting,electricpowertransformersandotherancillaryoperatingequipment
Figure8.6 (a)Avacuumoperatedcranefeedingprecastconcretesegmentstothering 40
buildareawhere(b)avacuumsegmenterectorliftsandplaceseachsegment
intotheringoftunnellining
Figure8.7 IllustrationofatailsealthatsealsthegapbetweentheTBM’stailskinandthe 42
extradosoftheringsoftunnelliningsegmentstopreventinflowofwaterand
loosegroundintothetunnelandTBMworkingenvironment
Figure8.8 ATBMoperator’sscreendisplayingmonitoreddataoftheannulargrout 43
injectionsystemandoperation
Figure9.1 Exampleofadriveinstructionsheet 45
Figure9.2 Spoilquantitymonitoringgraph 48
Figure9.3 (a)Anengineer’scontrolroommonitoringstationonthesurfaceand 51
(b)aclose-upviewofamonitoringscreen
Figure9.4 Exampleofadata-loggersheet 52
1 Introduction
The Closed-Face Working Group was formed initially by the British
Tunnelling Society (BTS) in 2000 as a result of tunnel collapses on
projects in Hull and in Portsmouth in November 1999 and May 2000
respectively. In both cases closed-face earth pressure balance tunnel
boring machines (TBMs) of less than 5m diameter had been used.
The BTS Committee was concerned that the industry in the UK
might not fully understand and appreciate every aspect of the control
ofmodernTBMsgiventheperceptionthatmodernclosed-facetunnel-
ling machines were capable of tunnelling through every type of soft
ground without major problems.
The first report by the Group is posted on the Society’s website at
www.britishtunnelling.org and is available in hard copy from the
BTS Secretary. The Group did not discover any failures in the opera-
tions of the TBMs used on the two projects in question but concluded
that there were areas of research that could prove useful should
financial and research facilities become available. Following what has
become known as the ‘Lavender Street incident’ on the Channel
Tunnel Rail Link (CTRL) London Tunnels Project in February 2003,
wherelarge-diameterclosed-faceTBMswereused,theBTSconsidered
it necessary to reconvene the Working Group.
The BTS had recently worked with the Association of British
Insurers (ABI) to publish a Joint Code of Practice on Risk Manage-
mentofTunnellingWorksintheUK(ABI/BTS,2003).Itisconsidered
that much of the content of the Joint Code of Practice reinforces the
content of this report.
Thefocusofthisreportisongroundstabilitytogetherwithmethods
ofgroundinvestigationandriskreduction.ItistheintentionoftheBTS
that this report is used as an adjunct to British Standards BS6164,
BS5930 and all other relevant BS and EU documents in order to
enhance the standards of safe tunnelling practice and when engaged
in tunnelling with closed-face tunnelling machines in particular. It is
also intended that the report will provide assistance to the Health
and Safety Executive and the insurance industry when assessing the
risks associated with closed-faced TBM tunnelling projects and evalu-
ating the proposed controls and mitigation methods.
It is not intended that the report should in any way replace the
guidance that is given in the BS6164 Code of Practice for Safety in
Tunnelling in the Construction Industry.
The BTS intends the report to be helpful for future challenging UK
projects including the proposed Crossrail 1 and 2 projects in London
and the planned Woolwich Extension of London’s Docklands Light
Railway.
Although the CTRL incident that acted as a catalyst for the writing
ofthisreportconcernedearthpressurebalancemachines(EPBMs),the
report considers both EPBMs and slurry tunnelling machines (STMs).
It does not consider the use of compressed air shields, i.e. those that
establish a compressed air plenum in front of a bulkhead in which an
excavator operates.
Closed-face tunnelling machines and ground stability. Thomas Telford, London, 2005 1
2 Technology of closed-face tunnelling
machines
2.1 Machine types Therearetwobasictypesof pressurisedclosed-facetunnellingsystems
– slurry tunnelling machines (STMs) and earth pressure balance
machines (EPBMs).
Slurry tunnelling machines were developed specifically for use in
cohesionless soils that contain little or no silt or clay. These machines
operatewithpipedhydraulicspoilremovalandtheslurryisregenerated
in a separation plant that removes the excavatedspoil from the slurry.
Earth pressure balance machines were developed for use in weak
cohesive soils that are capable of filling completely the excavation
chamber ahead of the pressure containing bulkhead or plenum in
order to provide positive pressure support to the tunnel face. The
ground or soil is required to be plasticised during the excavation pro-
cess so that it is capable of creating a plug or seal in the system’s
spoil extrusion screw conveyor in order to maintain pressure support
oftheface,resistgroundwaterpressure,anddischargespoilatatmos-
phericpressureforloadingintomuckhaulageskipsorontocontinuous
conveyor haulage systems.
Pure cohesionless soils and pure weak cohesive soils, however,
are rare. Consequently it is necessary to extend the application of
STMs into cohesive soils and of EPBMs into cohesionless soils. The
result is the necessity to provide a more extensive separation plant
forSTMsincohesivesoilsandforEPBMstheneedtoinjectcondition-
ing agents such as chemical foams and polymers into the plenum
and the screw conveyor housing to produce a more fluid/plasticised
spoil.
Slurry tunnelling machines and EPBMs were developed initially in
Japan and Europe. In Japan, STMs were developed in the 1960s with
EPBMs introduced in the mid to late 1970s. In Europe, STMs were
in use in the 1970s with a similar gap of about 10 years before the
first EPBMs were employed. Slurry tunnelling machines and EPBMs
haveseennumerousdevelopmentsandimprovementssincetheirincep-
tionandthemodernmachines,astypifiedbythoseusedtoexcavatethe
tunnels of the Channel Tunnel Rail Link (CTRL) under east London,
have continued the evolution of closed-face TBMs.
This section describes recent developments of closed-face TBM
technology designed to improve the ability of the systems to control
ground stability and operate safely.
2.1.1 Slurry machines
WithanSTM,excavationiscarriedoutbya rotatingcutterheadfitted
with picks or disc cutters or a combination of both. The excavated
materialismixedwiththefrictionlesssupportfluid,usuallyabentonite
suspension that is maintained at a predetermined positive pressure in
the plenum. This pressure reacts to any imbalances between the
volume of suspension supplied to the plenum and the amount of
suspension combined with excavated material removed from it. These
volume variations are unavoidable and pressure is maintained either
by controlling the volume differences with interlinked pumps and
valves or by the provision of either a compressed air reservoir or air
bubble. The bentonite tunnelling machine developed in the early
2 Closed-face tunnelling machines and ground stability. Thomas Telford, London, 2005