NATM Tunneling ppt

One of the best tunneling method is NATM. PPT is based on current project.

1. NATM
NEW AUSTRIAN
TUNNELING METHOD
Prepared by-Suman Paul

2. HISTORY OF NATM
ThetermNewAustrianTunneling
MethodPopularlyKnownasNATMgot
itsnamefromSalzburg(Austria).
ItwasfirstusedbyMrRabcewiczin
1962.Itgotworldwiserecognition
in1964.
ThefirstuseofNATMinsoftground
tunnelinFrankfurt(Europe)metroin
1969.
ThebasicaimofNATMisforgetting
stableandeconomictunnelsupport
systems.
Prepared by-Suman Paul

3. Need of PandohTakoliBypass
Project
SocialBenefit:Theprojectwouldhelp
expeditetheimprovementofinfrastructure
inHimachalPradeshandreducethetime
andcostoftravelfortrafficplyingonthe
stretch.
TravelTime:Traveltimewouldbereduced
by1.3hrto2hrs.
Infrastructure:Constructionof10new2
lanetunnelforatotallengthof16.8kmand
1existingtunneland19kmof4Lane
Highway.
Safety:Safetyoftravelerwillbeincreased
becauseofTunnelinfrastructureand4
LaneHighwayinfrastructure.
Prepared by-Suman Paul

4. DEFINITION OF NATM
TheNewAustrianTunnelingMethodisa
supportmethodtostabilizethetunnel
perimeterbymeansofsprayedconcrete
,anchorsandothersupportanduses
monitoringtoocontrolstability.
Prepared by-Suman Paul

5. BROAD PRINCIPLES OF
NATM
TheNATMintegratestheprinciplesof
thebehaviorofrockmassesunderload
andmonitoringtheperformanceof
underground constructionduring
construction.
Prepared by-Suman Paul

6. 7 FEATURES OF NATM
Mobilization of the strength of rock mass
Shotcreteprotection
Measurements
Primary Lining
Closing Invert
Rock mass classification
Dynamic Design
Prepared by-Suman Paul

7. FEATURES OF NATM
Mobilizationofthestrengthofrock
mass-Themethodreliesontheinherent
strengthoftherockmassbeingconserved
asthemaincomponentoftunnelsupport.
Primarysupportisdirectedtoenablethe
rocktosupportitself.
Shotcreteprotection-Looseningand
excessiverockmassdeformationshould
beminimizedbyapplyingalayer25-50mm
ofsealingshotcreteimmediatelyafter
openingoftheface.
Prepared by-Suman Paul

8. FEATURES OF NATM
Measurements-Everydeformationofthe
excavationmustbemeasured.NATM
requiresinstallationofsophisticated
measurement instrumentation.Itis
embeddedinlining,groundsuchasload
cells,extensometersandrelectors.
PrimaryLining-Theprimaryliningisthin.
Itisactivesupportandthetunnelis
strengthenednotbyathickerconcrete
liningbutbyaflexiblecombinationofrock
bolts,wiremeshandLatticegirders.
Prepared by-Suman Paul

9. FEATURES OF NATM
Closingofinvert–Earlyasfaras
possibleclosingtheinvertsoasto
completethearchactionandcreatinga
load-bearingringisimportant.Itis
crucialinsoftgroundtunnels
Rockmassclassification-The
participationofexpertgeologistisvery
importantastheprimarysupportaswell
asthefurtherdesigningofsupportsetc
duringtheexcavationofrockrequires
theclassificationoftherockmass.
Prepared by-Suman Paul

10. FEATURES OF NATM
DynamicDesign–Thedeigningis
dynamicduringthetunnelconstruction.
Everyfaceopeningclassificationofrock
isdone,andthesupportareselected
accordingly.Alsothedesignisfurther
reinforcedbasedonthedeformationas
noticedduringthemonitoring.
Prepared by-Suman Paul

11. PSYCOLOGY BEHIND
NATM
a“designasyougo”approachto
tunnellingprovidinganoptimized
supportbasedonobservedground
conditions.
a“designasyoumonitor”approach
basedonobservedconvergenceand
divergenceintheliningaswellas
prevailingrockconditions.
Prepared by-Suman Paul

12. WHY NATM
Flexibilitytoadoptdifferentexcavation
geometriesandverylargecross
sections.
Flexibilitytoinstalladditionalsupport
measures,rockbolts,dowels,steelribs
ifrequired.
Easytoinstallawaterproofmembrane.
Easytoinstallprimarysupport,i.e.
shotcrete.
TBM(TunnelBoringMachine)isnotan
effectivemethodascomparedtoNATM
.
Prepared by-Suman Paul

13. Prepared by-Suman Paul

14. SEQUENCE OF EXECUTION
OF NATM
Portal Development
Survey and Profile making
Drilling Hole and Rock bolting
Loading Explosive
Charging (20 to 30 min)
Blasting
DefumingThrough Ventilation Pipe
Removal Of Muck
Scaling/Chipping With Boomer
SHOTCRETE IstLayer ( Upto50mm )
SURVEY
SUPPORT SYSTEM (Wire Mesh , Steel Rib/Lattice
Girder )
SHOTCRETE 2ND LAYER (150 –200mm)
Systematic Rock Bolting
Prepared by-Suman Paul

15. Prepared by-Suman Paul

16. PORTAL DEVELOPMENT
Portal development is the process to
stabilize the entrance and exit of the
tunnel
Prepared by-Suman Paul

17. SURVEY AND PROFILE
MAKING
Thebasicprocedureoftunnelsurveying
istoalignthecenterlineintheground
andtransferthattothetunnel.
Markingofprofileasperdesignand
drawingofthattunnel.
Prepared by-Suman Paul

18. SURVEY AND PROFILE
MAKING
Prepared by-Suman Paul

19. DRILLING HOLE & ROCK
BOLTING
Processofmakingholeinrocksurface
forblastingandrockbolting.
Equipmentused-DrillJumbo,Crawler
Drill
Prepared by-Suman Paul

20. DRILLING HOLE
Prepared by-Suman Paul

21. LOADING EXPLOSIVE
TYPESOFEXPLOSIVES-
Explosivesbasedonchemicalnature
Highordetonatingexplosives-Processis
extremelyrapid,almostinstantaneous.
LowordeflagratingExplosives-Lowvelocity
ofburningandproducepressureby
progressiveburning
Explosivesbasedonavailability
Powderexplosives
DisruptiveexplosivesorDynamites
Prepared by-Suman Paul

22. LOADING EXPLOSIVE
Prepared by-Suman Paul

23. CHARGING
Aexporterhavingaredlight/buttonusedforblasting
Startchargingfaceatleast15minutesafterstart
drillingoutasafeposition.
Chargingshouldbedonealwaysfromthetopto
bottom,itshouldbedone200mawayfromthe
explosivearea.
Takeblastingcordwithinthebasketandcorrect
detonatorstraightafterholeisfinishedcharged.
Assoonaschargingoutofthebasketisdone
prepareignition-cableandcorrectelectricaldets.
Pushredlightforblastafteritgivesignal.
Wheel-loaderandDumpertruckshavetobe
organizedbeforeblastingandplacedinsideTunnel.
Prepared by-Suman Paul

24. BLASTING
Definition-Theprocessofbreakingrocks
intosmallerpiecesbyuseofexplosives.A
pictureofphasewithexplosiveloading
Readyforblasting.
ControlBlasting
Volumeexcavationdifficulttoachieve
Permission&licenseismustforusage,storage
&transportation
Limitedpermissionavailableforusage,whenits
must
Usageisstillrestrictedlikedrill&blast
Prepared by-Suman Paul

25. BLASTING
Prepared by-Suman Paul

26. VENTILATION IN TUNNEL
Ventilationisrequiredbecauseof:
RemoveDustandGascausedbydrilling,
blasting,loadingofexcavatedmaterialsand
Shotcreting.
Exhaustgasandsmokedischargedby
diesel
Poisongasmadefromexplosiveororganic
solvent
Poisongas,flammablegasoroxygen
shortagegasinground
Hightemperatureandhighhumidity
Prepared by-Suman Paul

27. VENTILATION IN TUNNEL
Prepared by-Suman Paul

28. FACE MAPPING
Aftertheblast,geologicalmappingof
excavatedfacearebeingdonewith
theirorientationwithgeologicalfeatures
(Joints,Faults&Folds)w.r.ttunnelis
prepared.
BasedonGeologicalobservation
supportsystemisdecided,andsupport
isbeinginstalled.
Prepared by-Suman Paul

29. MUCKING
Muckingisaprocessinwhichmuckis
carriedinthedumptruckafterblasting
andthrowoutsidethetunnel.Mucking
hastobenotlowerthanthebottom
plateoflastlatticegirder.
Prepared by-Suman Paul

30. MUCKING
Prepared by-Suman Paul

31. SACLING/CHIPPING
Scaling/Chippinginprogressof
removingloserockfromheadingof
tunnelandithelpstomakespacefor
tunnelsupportbyremoveundercutafter
blasting.
Scaling/chippingisdonewithboomer
machinetoremovethemuckwhichstick
tothephase
Prepared by-Suman Paul

32. ROCK MASS
CLASSIFICATION
Theexcavationintherockisdependent
ontherockclassbasedonseveral
factorssuchas–compressivestrength
ofrock,watercondition,numberof
cleavages,conditionofcleavages,dip
andstikeoftherocketc.
Therearevariousapproachesof
classificationoftherockmassandmost
predominantlyareRQD,RMR andQ
factoroftherockmass.
Prepared by-Suman Paul

33. ROCK QUALITY
DESIGNATION INDEX (RQD)
TheRockQualityDesignationindex
(RQD)wasdevelopedtoprovidea
quantitativeestimateofrockmass
qualityfromdrillcorelogs.RQDis
definedasthepercentageofintactcore
pieceslongerthan100mminthetotal
lengthofcore.Thecoreshouldbeat
leastNWsize(54.7mmindiameter)
andshouldbedrilledwithadouble-tube
corebarrel.
Prepared by-Suman Paul

34. RMR VALUE
RMR value dendsupon the following
factors:
1. Uniaxial compressive strength of rock
material. 2. Rock Quality Designation
(RQD). 3. Spacing of discontinuities. 4.
Condition of discontinuities. 5. Groundwater
conditions. 6. Orientation of discontinuities.
Prepared by-Suman Paul

35. Q FACTOR
QFactor:Itdependsonthefollowing:
i)Blocksize
ii)Interblockshear
iii)Activestress
iv)Reductionforjointwaterflow
v)Presenceofweaknesszones
Qfactorvariesfrom0.01to1000i.e.
fromexceptionallypoorrockto
exceptionallygoodrock
Prepared by-Suman Paul

36. ROCK SUPPORT SYSTEM
Prepared by-Suman Paul

37. COMPONENTS AND
SEQUENCE OF EXECUTION
AFTER BLASTING
I.Sealing Shotcrete –Shotcrete 25-50mm
generally
II.Fixing of Lattice Girder –lattice girder is 3
Bars of steel reinforcement placed at three
corners of triangle with 8mm steel bar for
connection. Easy to handle comparison of
steel ribs.
III.Fixing of wire mash–generally used 6mm
thick wires (fig 6 )
IV.Primary Lining with Shotcrete–In layers
each not thicker than 150mm
V.Rock Bolting –discussed separately
VI.Pipe Fore poling –Used for crown support
for next Excavation cycle ( for Rock Class
after III only)
Prepared by-Suman Paul

38. SHOTCRETE
Shotcreteisthegenericnameforcement,
sandandfineaggregateconcreteswhich
areappliedpneumaticallyandcompacted
dynamicallyunderhighvelocity”.
Pre-shotcrete
Firsttheprofileandtheafterneedstobe
washeddownsothattherewillbeagood
connectionbetweenrockandshotcrete.
Areaswhereareoverbreaksituationsshouldbe
sprayedfirstwithathinlayer(max10cm).
Theshotcreteneedstobesprayedfromthe
bottomupwardstohaveagoodabutmentfor
uppershotcrete.
Prepared by-Suman Paul

39. TYPE OF SHOTCRETE
WetMixShotcrete:
Allingredients,includingwaterarethoroughly
mixedandintroducedinthedeliveryequipment.
Wetmaterialispumpedtothenozzlewherethe
compressedairisaddedtoprovidehighvelocity
forplacementandconsolidationofthematerial
intothereceivingsurface.
DryMixShotcrete:
Pre-blendeddryordampmaterialsareplaced
intothedeliveryequipment.Compressedair
conveysmaterialthroughahoseathighvelocity
tothenozzle,wherethewaterisadded.Material
isconsolidatedonthereceivingsurfacebyhigh
impactvelocity.
Prepared by-Suman Paul

40. DRY VS WET SHOTCRETE
Dry Shotcrete
I.Less power input
is required.
II.Low initial cost,
low maintenance
and cheaper
III.Productivity is
comparatively
low
IV.Rebound is
greater
Wet Shotcrete
I.Greater power
required.
II.Costlier process.
III.Higher
productivity
about 10-16
cum/hr
IV.Rebound is less
Prepared by-Suman Paul

41. SHOTCRETE
Prepared by-Suman Paul

42. TUNNEL SUPPORT
SYSTEM
Support acting by applying a confining
pressure to the surrounding ground
Shotcrete
shotcrete with lattice girders
Support applying both a confining
pressure and acting as reinforcement of
the surrounding ground
Un-grouted mechanically or chemically
anchored rock bolts
Grouted (resin or mortar) rock bolts
Driven anchor bars
Prepared by-Suman Paul

43. TUNNEL SUPPORT
SYSTEM
Systems providing plain "brute strength”
support
heavy steel ribs
lattice girders
steel linings
concrete segments
driven tubes (umbrella arch)
Shields
Systems which consolidate the ground to
amend its geotechnical and/or hydrological
properties
consolidation grouting
compressed air
freezing
Prepared by-Suman Paul

44. SUPPORT SYSTEM AS PER
ROCK CLASSIFICATIONS
Prepared by-Suman Paul

45. WIRE MESH
Wiremesh
Wiremeshisusedtosupportsmallpiecesof
looserockorasreinforcementforshotcrete.
Stabilizationofappliedshotcreteuntilsetting
andhardening
Increaseofshearstrength
Preventingdroppingofshotcreteportion
aftercrackingorfailingofthelining.
SIZE:Standardsizeis150x150x6mm
Prepared by-Suman Paul

46. FOREPOLING
TheForepolingUmbrellaSystem(FUS)
hasprovedtobeanefficientsoil
reinforcementmethodinopenface
tunneling.
.Thesystemcomprisessteelpipes
installedfromthetunnelfacetoformaroof
abovethetunnelheadingthereby
contributingtodecreasingthedeformations
causedbytunnelingandincreasingthe
tunnelheadingstability.
Generallyforepolingisusedforsoftground
rockconditions.
Prepared by-Suman Paul

47. FOREPOLING
Prepared by-Suman Paul

48. LATTICE GIRDER
Itisusedwhenrockisloose.
ItisusedinclassC,DandFofrock.
FunctionsofLatticeGirder
SteelRib/LatticeGirderCompositestructure
oflatticegirderandconcreteconfinedto
loaddistribution.
Carryingof“Green”shotcrete.
Profilecontrol
SupportforforepolingPlacingoflattice
girder
Prepared by-Suman Paul

49. LATTICE GIRDER
Prepared by-Suman Paul

50. ROCK BOLTING
Arockboltisalonganchorbolt,forstabilizing
rockexcavations,whichmaybetunnelsor
rockcuts.Ittransfersloadfromtheunstable
exterior,totheconfined(andmuchstronger)
interioroftherockmass.
Rockboltareusedtosupporttheupperpartof
thetunnel.
Itisinsertedataninclinedangle40-60degree
intherock.
TypeofRockbolt
SDA:-SelfDrillingAnchor
SN:-StoreNorphusRockbolt
Prepared by-Suman Paul

51. Prepared by-Suman Paul

52. TYPES OF ROCK BOLTS
1)SNType–Normalsteeltorsteelbarsof
dia28mmandabove(generallyusedas
32mm)withcementgrout,sometimethe
resinpouchescanbeusedforbetter
anchorage.
2)SDR–Theseareselfdrillingtypeof
Rockboltswithsacrificialbitatstart,
suitableforrapidlycollapsingsoilswhere
thedrilledholecollapseswhendrillbiteis
withdrawn.
3)ExpansionRockBolts–Swellextype.
Therockboltisinflatedafterinsertionwith
thewaterpressureforbetteranchorage.Prepared by-Suman Paul

53. SECOND LAYER OF
SHOTCRETE
2
nd
layerofshotcreteissprayedtocover
latticegirderandstandardthicknessof
shotcreteis150mmto200mm.
Functionof2
nd
Shotcrete-
1.AssealingShotcrete:
Avoidsfirstlooseningofthesurroundingground.
Closesjointsandpreventsfall-downs;so
activatingtherockarch.
Sealsthesurroundingground.
2.Asmainshotcrete(carryingmember):
Tocarrytheloadintroducedbythegroundinthe
lining.
Prepared by-Suman Paul

54. TUNNEL LINING &
PAVEMENT
Fixing of Reinforcement / Waterproofing
Membrane
Erection of Concrete Lining Gantry
Concreting in Tunnel
GSB laying in invert
DLC laying in invert
PQC laying in invert
E&M works
Prepared by-Suman Paul

55. FIXING OF REINFORCEMENT
/ WATERPROOFING
MEMBRANE
Prepared by-Suman Paul

56. ERECTION OF CONCRETE
LINING GANTRY
Prepared by-Suman Paul

57. CONCRETING IN TUNNEL
Prepared by-Suman Paul

58. GSB LAYING IN INVERT
Prepared by-Suman Paul

59. DLC LAYING IN INVERT
Prepared by-Suman Paul

60. PQC LAYING IN INVERT
Prepared by-Suman Paul

61. CONCEPT OF 3D
MONITORING
3dmonitoringisnewtechniqueusingfor
takingtherightalignmentofthetunnel
Opticaltargetsareusedfordetermining
thecoordinatesformeasurements
Thecoordinatesshouldbechecked
daily
Itisnecessaryforthetunnelasbyitwe
knowanydisplacementandwrong
alignments
Prepared by-Suman Paul

62. POINTS TO CARRY OUT A
SUCCESSFUL NATM
PROCESS
Considerationofrockmechanics
Selectionofaproperprofile
Designofflexiblesupportandslenderlining(in
rock)
Carefulexcavation
Maintenanceofrockstrength,avoidanceof
looseningandover-breaks
Directcontactofrock/soilandsupport
Continuous controlby geotechnical
measurements
Installationofsupportwithoutdelayandin
correct
sequence
Prepared by-Suman Paul

63. Prepared by-Suman Paul

64. General
Optical Target
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65. Prepared by-Suman Paul

66. General
Optical Displacement Monitoring
Free Stationing
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