04_NTH_Project Report 1-94 Hard Rock Tunnel Boring

8/12/2019 04_NTH_Project Report 1-94 Hard Rock Tunnel Boring

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ONT NTS P GEPREF CE

INTRODUCTION 3

CROSS SECTIONS 7

2 DV NCE R TE 4

3 CUTTER LIFE 33

4 COSTS 4

5 T U N N l N ~ 69

6 GEOLOGY 8

7 ORING PROCESS 5

8 GROUND SUPPORT 34

PPENDICES 45


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PREF E

HARD ROCK TUNNEL BORINGPROJECT REPORT 94

The report is part of a project programme on tunnelling consisting of the followingreports:

4-79 TUNNELLINGLarge Cross Sections

1-81 SHAFT EXCAVATION8-87 DEEP AND LONG UNDERSEA TUNNELS2-88 TUNNELLING

Prognosis for Drill and Blast3-88 TUNNELLING

Costs for Drill and Blast5-88 ROCK CAVERNS8-88 ROAD TUNNELS

Drill and Blast or Tunnel Boring13-90 DRILLABILITYDrilling Rate Index Catalogue

10A-91 TUNNEL ROCK SUPPORTBolting

lOB-91 TUNNEL ROCK SUPPORTShotcrete

10C-91 TUNNEL ROCK SUPPORTConcrete Lining

179 TUNNELLINGVentilation

14A-93 ROCK BLASTING TECHNIQUEBlasting Vibrations

94 HARD ROCK TUNNEL BORING7-95 SINKING DEEP SHAFTS

Drill and Blast

Available in English. See also Appendix C.


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PREF E

A considerable amount o information o tunnelling has been brought up to dateand systematized through the reports to be used for

economic dimensioning o tunnels choice of tunnelling alternative time planning cost analysis tender budgeting and cost control choice o tunnelling method and equipment

The performance and cost models o these reports are also available as programsfor personal computers:

Drill Pattern Drill and Blast Tunnelling Hard Rock Tunnel Boring Prognosis and Costs Hard Rock Tunnel Boring Transport Analysis Tunnelling Ventilation Drillability Drilling Rate Index Catalogue Joint Plotting Joint Diagrams

Two programs for follow up o tunnel boring are also available: Cutter Consumption Machine Utilization

Trondheim March 1995

Professor2


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INTRO U TION ont nts

Page 1 PROJECT REPORT 1 94 40 2 BACKGROUND 50 3 TUNNEL BORING VS DRILL AND BLAST TUNNELLING 6

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INTRO U TION

1 PROJECT REPORT 94

1 Project Report 94

The report provides-methods and necessary data for calculation of timeconsumption and costs for tunnel boring. Geological parameters of significancefor performance and costs are presented in detail. The boring process withchipping mechanism and cutter abrasion is described.

The report also gives a brief treatment of cross section conditions for tunnelboring, a description of equipment systems behind the TBM, including transportation of muck from the TBM to the rock dump.The 1994 edition is an updated version of the project reports 1-76, 1-79, 1-83 and1-88. The report has been prepared by a project group consisting of the civilengineers Bard Sandberg, Amund Bruland, Jan Lima and Professor OddJohannessen. Dr.ing. Torgeir Blindheim has made substantial contributions tothe English edition.The report has been completed by Amund Bruland.The project group alone is responsible for the conclusions of the report.Financial support has been granted by

- Luftfartsverket- Statkraft Anlegg AS- Vegdirektoratet- Norwegian Research Council.

For reference, we ask for the following to be used:University of Trondheim, NTH-Anleggsdrift l994 :Project Report 1-94 HARD ROCK TUNNEL BORING

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INTRO U TI IN

0.2 BACKGROUND

2 Background

The prognosis model s based on job site studies and statistics from tunnelling inNorway and abroad. The data have been systematized and normalized. The resultsare regarded as being representative for well organized tunnelling.The prognosis model has been developed continuously since 1975. During thisperiod it has gone through several phases:

prognosis model for performance and costs developed on the basis ofcollected job site datathe model was verified and adjusted to data from running jobsthe model has been applied in the planning of a number of tunnelprojects for calculation of time consumption and costs for tunnel boringthe same tunnel projects have then been studied during construction andhave given additional data resulting in adjustments of the model.

job sites with 230 km of bored tunnel have been carefully mapped. Data fromjob sites abroad has also been studied. In some of the projects tunnel boring hasbeen utilized under very demanding rock conditions. All together this has resultedin fundamentally new knowledge about tunnel boring which s incorporated inProject Report 1 94.

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INTRO U TION 3 Tunnel Boring vs Drill and Blast Tunnelling0.3 TUNNEL ORING VS RILL AND BLAST TUNNELLING

When comparing drill and blast tunnelling to tunnel boring, the comparison musttake into account cross section area, time consumption and total costs.n addition to the direct tunnelling costs, the total costs include rock support,cleaning of invert, construction and operation of transport facilities, communications and power supply, labour housing and auxiliary plants, share of generalcosts, and finally, interest costs during the construction period. See also example inProject Report 3-88 TUNNELLING Costs for Drill and Blast.Most of the items vary with the tunnelling method, either because of the methoditself rock support, cleaning of invert or because of different time consumptionoperation of all auxiliary functions, interest in construction period .Tunnels may be longer for tunnel boring than for drill and blast tunnelling, due toincreased advance rates and reduced ventilation requirements. This facilitates amore favourable tunnel system layout, e.g. with fewer adits.

For geological reasons, it may be advantageous to choose a different route fortunnel boring than for drill and blast tunnelling. is important that the method s evaluated at an early phase in the planningprocess - to ensure full benefit of possible gains by the use of tunnel boring.

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ROSS S TIONS ont nts

Page GEOMETRICAL CONDITIONS 8

Tunnel Profile 8 2 Tunnel Slope 8 3 Curve Radius 8

2 WATER TUNNELS 9

3 SEWAGE TUNNELS 4 ROAD TUNNELS 2

5 RAILROAD TUNNELS

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ROSS S TIONS1.1 GEOMETRI L ONDITIONS

1.11 Tunnel Profile

Geometrical onditions

Tunnel boring gives a circular profile with smooth surface. Machines withdiameters from 1.2 m to 12 m 1.1 m2 to 113 m2) have been developed for boringin hard rock.The diameter of a given machine may be changed when rebuilt. Alterationsamounting to 10 - 15 are possible, depending on diameter and manufacturer.or some machines, the diameter may be changed even more; 100 fromsmallest to largest diameter.)

1.12 Tunnel SlopeTunnel boring machines can be built for boring at all tunnel slopes. The slope islimited by the muck transport system.

Track transport must be used for diameters under approximately 6 m. The slope isthen limited to approximately 2 . Trackless transport is feasible for diametersover approximately 7 m. The practical slope limits are then 1:6, presupposing aroadway pavement of high quality. Both trackless and track transport demand aminimum slope of 0.2 for required drainage of the tunnel. Shafts can be boredwith slope from 25 to vertical. Scraping or flushing of muck facilitates boring ateven lower slope. Development of special equipment for trackless transport insmall cross sections, pumping of muck or use of conveyors may alter the slopelimitations.

1.13 urve RadiusThe minimum curve radius for tunnel boring depends on both the TBM and theback-up equipment. Tunnel boring machines have a minimum curve radius of 40 80 m without boring 15 - 25 m). The back-up equipment, i.e. the conveyor belt,determines the minimum curve radius. When using long back-up equipment, theminimum curve radius is 150 - 450 m. The possible conflict between the back-upequipment and installed rock support also affects the minimum curve radius.

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ROSS S TIONS

1.2 W T R TUNNELS

2 Water Tunnels

Loss of head in a bored tunnel is smaller than in a blasted tunnel with the samecross section, because of the circular, smooth profile.Figure 1 1 shows the relation between the cross section of a blasted and a boredtunnel with the same capacity hydraulic equivalent cross sections). The diagram iscalculated on the basis of the assumptions shown i Table 1.1.

Cross Section 8 m2 2 m2 5 m2 lasted cross section- Absolute roughness, mm- Manning s number 32.8 33.9 34.6 ored cross section schistose rock- Absolute roughness, mm 4.5 4.5 4.5- Manning s number 62.7 61.8 60.5 ored cross section homogenous rock- Absolute roughness, mm 3.0 3.0 3.0- Manning s number 65.9 63.5 62.4

Table 1 1 Roughness for varying tunnel cross sections.

Marginal costs for bored tunnels increase with increasing cross sections, whereasthey decrease for drill and blast tunnels. Furthermore, the marginal costs for boredtunnels are very dependent on the rock mass borability. For economic optimizationof cross sections, a different relation between blasted and bored cross sections thanthose shown in Figure 1 1 will be obtained. Such calculations must be carried outfor each individual project.The relation between economic optimal cross sections for a specific project drilland blast tunnelling and tunnel boring) is shown in Figure 1.2.

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ROSS S TIONS

3 SEWAGE TUNNELS

3 Sewage Tunnels

In blasted sewer tunnels it is often necessary to concrete a V shaped channel inthe invert to achieve a self cleaning effect for low flow rates.In bored tunnels it is not necessary to concrete such a channel because thecircular cross section is sufficiently self cleaning when bored with accurate controlof slope. is presupposed that all TBM muck and other objects are removed fromthe invert.


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1. ROSS S TIONS 4 ROAD TUNNELS

4 Road Tunnels

The circular cross section is not suited for road tunnels. Due to required traffic areaand free clearance, cross sections will be unnecessarily large bored, see Figure1.3.Cross sections will be better utilized the lower part o the tunnel is enlarged byblasting, see Figure 1.3. As little slashing as possible must be done in order topreserve the smooth surface o the bored tunnel. However, slashing is time consuming, and often prolongs the construction time.

Another alternative is to bore this part o the cross section as well. Equipment forthis purpose is being developed.Road tunnels are discussed in more detail in Project Report 8-88 ROADTUNNELS Drill and Blast or Tunnel Boring Norwegian edition only .

0

Traffic area

Bored cross section

Figure 1.3 Cross sections for road tunnels.

Traffic area

Bored and slashed cross section

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1 ROSS S TIONS 5 RAILROAD TUNNELS

1 5 Railroad Tunnels

Cross section conditions for railroad tunnels are similar to those for road tunnelsbut the cross section may often be better utilizedFigure 1 4 shows relevant tunnel profiles for single track railroad tunnels electrictraction

EoN

BoringA=63 6m2 Boring and slashingA=44 2 10 0=54 2m2Figure 1 4 Cross sections for railroad tunnels


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DV N E R TE ont nts

Page2 1 PENETRATION PARAMETERS 15

2 1 Introduction 152 11 Rock Parameters 152 12 Machine Parameters 18

2 2 NET PENETRATION 212 3 Introduction 212 21 Fracturing 212 22 Basic Penetration 232 23 Net Penetration Rate 252 24 Torque Demand 252 25 Other Advance Rate Limitations 26

2 3 GROSS ADVANCE RATE 272 3 Introduction 272 31 Machine Utilization 272 32 Additional Time Consumption 3

2 4 EXAMPLE OF APPLICATION 31

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2 DV N E R TE2 1 PENETRATION PARAMETERS

2.10 Introduction

2 enetr tion r meters

Net penetration rate depends on rock properties and machine parameters.

Rock Mass Parameters- fracturing- Drilling Rate Index, DRI- abrasiveness, CLI- porosity

Table 2 1 Machine and rock parameters.

2.11 Rock r meters

Machine Parameters- cutter thrust- cutterhead rpmcutter spacing- cutter size and shape- installed power

To estimate time consumption and costs, a geological preinvestigation, adjusted totunnel boring, is required. This section gives a numeric description of requiredgeological parameters and may be an aid at an early planning phase. See Chapter 6for detailed studies of geological conditions.

Degree of FracturingThe rock mass fracturing is the most important penetration parameter for tunnelboring. In this context, fracturing means fissures or joints with little or no shearstrength along the planes of weakness. The less the distance between the fracturesis the greater the influence on the penetration rate is.Rock mass fracturing is characterized by degree of fracturing type and spacingand the angle between the tunnel axis and the planes of weakness.Joints Sp : Includes continuous joints that can be followed all around the tunnelprofile. They can be open e.g. bedding joints in granite or filled with clay orweak minerals, e.g. calcite, chlorite or similar minerals.

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2. DV N E R TE 2 Penetration Parameters

Fissures 8t : Includes non-continuous joints can only be followed partly aroundthe tunnel profile , filled joints with low shear strength and bedding plane fissurespartings , e.g. as in mica schist and mica gneiss.Homogenous Rock Mass Class : Includes massive rock without joints orfissures may appear in intrusive dikes, sills, batholites, etc. . Rock mass with filledjoints with high shear strength e.g. joints healed with quartz, epidote, etc. mayapproach Class \\The degree of fracturing in systematically fractured rock mass is divided intoclasses for practical use when mapping see Table 2.2 . The classes include bothspace between and type of weakness planes. Figure 2.1 shows recorded fractureclasses for various rock types in bored tunnels.

Fracture ClassQoints Sp/fissures St

o0 1I-IIIIIV

Distance betweenPlanes of Weakness[cm]

16080420105

Table 2.2 Fracture classes with corresponding distance between planes ofweakness.

Rock DrillabilityRock drillability is evaluated on basis of the Drilling Rate Index DRI and theCutter Life Index CLI. The test methods are described in Project Report 13-90DRILLABILITY Drilling Rate Index Catalogue. Variation of DRI and CLI forsome rock types is shown in Figures 2.2 and 2.3 data from Norwegian tunnels .The influence of rock porosity is described in Section 6.2.

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DV N E R TE

LimestoneCalcareous shaleGreenshistPhylliteMica shistMica gneissGranitic gneissAmphibolitic gneissQuartz shistQuartziteBasaltQuartz diorite(Trondhjemite) I I I

2 1 Penetration Parameters

Io 1 II III III/IV IVFigure 2 Recorded degree of fracturing for various rock types

AmphibolitePhylliteMica gneissMica schistGneissGraniteGranitic gneissGreenstoneLimestoneQuartziteShaleSandstone

o 10 20 3 4010 25 50 75 90

50 60 70 80 9 100Drilling rate index, DRI

Figure Recorded Drilling Rate Index for various rock types

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DV N E R TE

AmphibolitePhylliteMica gneissMica schistGneissGraniteGranitic gneissGreenstoneLimestoneQuartziteShaleSandstone


--o 10 20 30 40 50 60 70 80 90 100

Cutter life index CLI10 25 50 75 90

Figure 2.3 Recorded Cutter Life Index for various rock types.

2 2 Machine Parameters

To estimate advance rate and cutter life the machine parameters are required. Atan early stage o planning the parameters must be assumed.

Cutter ThrustFigure 2.4 shows a general outline o maximum gross average thrust p r cutter discas a function o cutter diameter and TBM diameter.

Cutterhead RPMThe cutterhead rpm is inverse proportional to the cutterhead diameter. This isbecause one needs to limit the rolling velocity o the peripheral cutter. Figure 2.5shows cutterhead rpm as a function o cutterhead diameter and cutter diameter.


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DV N E R TE 2 Penetration Parameters

MBkN/c320280240200 9 m m ~

6 U ~ ~2 3 6 7 8 9 1

TBM diameter. m

Figure 2.4 Recommended maximum gross average thrust per disc.

RPM rev/min I 1 de432 500mm15 2 de=394mmf 1. I 3 de 356mm

.2. 10 f 3. I

J

5 I

i

4 5 6 7 8 9 0TBM diameter m

Figure 2.5 Cutterhead rpm.


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ADVANCE RATE

605

4

3


de 500mm

4 0 5 0 6 0 7 0 8 0 9 0

Figure 2 6 Normal number of cutters on the cutterhead

PbmkW35

TBM diameter m

de483 500mm

2500

1500

500

4 5 6 7 8 9

Figure 2 7 Normal installed cutterhead power

TBM diameter m


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ADVANCE RATE

2 2 NET PENETRATION2 2 Introduction

2.2 et enetration

Net penetration rate is defined as meters tunnel bored per hour when the cutterheadrotates with thrust against the face.

2 21 FracturingFracturing is expressed by the fracturing factor ks which is dependent on thedegree of fracturing type and spacing and the angle between the tunnel axis andthe planes of weakness, aThe orientation of weakness planes is determined from measurements of strike anddip.

a = arcsin sina f sin at -

= strike anglea = dip angleat = tunnel direction.

[2 1 ]

The fracturing factor for fissures and joints is shown in Figure 2.8, as a function offissure or joint class and angle between the tunnel axis and the planes of weakness.For more than one set of weakness planes, the total fracturing factor is as follows:

nk k n 0.36s lot SI

i = 1

k = fracturing factor for set no. in = number of fracturing sets.

[2.2]

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DV N E R TE 2 2 Net Penetration

The rock mass properties for TBM boring is expressed by the equivalent fracturingfactor

ko1 25

[2 3]

21

75 1 ks 0 362 ks > 2 00

4

2 3 4 5 6 7 8DRI

- 1 2 3 4 5 6 7 8 9

Angle between tunnel axis and planes weakness

Figure 2 8 Fracturing factor Correction factor for DRI 49


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2. DV N E R TE

2.22 Basic Penetration

2.2 Net Penetration

Basic penetration in mm/rev as a function of equivalent thrust and equivalentfracturing factor is shown in Figure 2.9. For cutter diameter and average cutterspacing different from Figure 2.9, equivalent thrust is given by:

iomm/rev

1

8

6

kN/cutter

, wr

[2.4]

I Equivalent thrust 300kN/c t-250 kN/c t

200 kN/cC:

5 kN/c

4

2

100 kN/c It

5 1 1 5 2 2 5 3Equivalent fracturing factor kekv

Figure 2.9 Basic penetration. de = 483 mm and ae = 70 mm.


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2. DV N E R TE 2.2 Net Penetration

- ; - ~ .- - - ; ,~ - - . . ,..

1 4 ~ ~ E > ~ b

3 34 38 4 46 5Cutter diameter, mm

Figure 2.10 Correction factor for cutter diameter de 483 mrn.

-1 O S ~ ~ ~ ~ m :. . ,- : . ,= . . j o : \ ~ . - H - + + + - + - 1 ~ + + - o - t - - < - + + - l - + - - t + - t - t - + - t - t - + - . . . . . . . . - j - - f + . . . . . ,; . .

. , :: - . . . . .:

6 65 7 75 8 85Average cutter spacing, mm

Figure 2.11 Correction factor for average cutter spacing ac * 70 mrn.

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ADVANCE RATE

2.23 Net Penetration ate

Net Penetration

Net penetration rate I is a function of basic penetration and cutterhead rpm.

I = i RPM . ~o 1000

2.24 orque Demand

m/hr [2.5]

For high penetration or when boring in fractured rock, one must check that there issufficient cutterhead power installed to utilize the estimated thrust. The machine istorque limited if the installed power is too low to rotate the cutterhead for a givenpenetration. Then the thrust must be reduced until the required torque is less thanthe torque capacity. Necessary torque is given by:

kNm [ 6]

0.59 =rtbm =N tbm =kc =

relative position of the average cutter on the cutterhead. When thecutterhead design is known, the factor may be calculated, see[7.6].cutterhead radiusnumber of cutters on the cutterheadcutter coefficient rolling resistance , see [2.7].

[2.7]

Figure 2.12 shows the cutter constant Cc as a function of cutter diameter. Necessarytorque decides the installed power. Necessary installed power is given by [2.8].

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2. DV N E R TE

T 2 1t . RPMn60

. .

I- -t-+-Kfi lrCc .. . .

; 0

O 5 t. t-+:t::;t;+tt:l . h : .::\ .

. .t ;..

kW)

2.2 Net Penetration

[2.8]

3 34 38 42 46 5

Figure 2.12 Cutter constant.

For details on torque demand, see Section 7.23.

2.25 Other Advance Rate Limitations

Cutter diameter, mm

Besides limitations due to available torque, the system s capacity TBM and back-up equipment) for muck removal may limit the net penetration rate. Particularly,muck removal may limit the penetration rate for large diameter machines.When boring through marked single joints or heavy fractured rock, it may benecessary to reduce the thrust due to too high machine vibration level and veryhigh momentary cutter loads.

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DV N E R TE

2 3 GROSS ADVANCE RATE2.30 Introduction

2.3 Gross Advance Rate

Gross advance rate is given in meters per week as an average for a longer period.Gross advance rate depends on net penetration rate, machine utilization and thenumber of working hours during the period.

2 31 Machine UtilizationThe machine utilization is net boring time expressed in per cent of total tunnellingtime. Total tunnelling time includes

1 boring Tb2 regripping Tt3 cutter change and inspection Tc4 maintenance and service of TBM Ttbm5 maintenance and service of back-up equipment T k6 miscellaneous Ta.

The activities are expressed in hours per kilometre. Time consumption used in thisreport is representative for the better part of today s tunnelling practice. Themachine utilization is given by:

u = ) [2 9]

BoringBoring time depends on net penetration rate

1000I hrlkm) [2.10]

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ADVANCE RATE

Regripping

2 3 Gross Advance Rate

Regripping time depends on stroke length of the thrust cylinders and time perregrip.

1000 . tl k60 . 1s hr/km

[2.11]

s = stroke length, typically 1.5 - 2.0 mtl k = time per regrip.

As an average, time per regrip te k is 4.5 minutes. Time consumption varies withgripper hold, stroke length, TBM diameter, boring in curves and capacity of thehydraulic system. Under favourable conditions the time consumption will besomewhat lower, but may increase substantially under difficult conditions.

Cutter ChangeTime for cutter change and inspection depends on cutter ring life Hh net penetration rate I and time per changed cutter te.

1000 . te60 . H . Ih hr/km

[2.12]

Time per changed cutter varies with the cutter size. Typically time consumption iste =te =Hh =

45 minutes for cutter diameter de :5 432 mm 17 inches6 minutes for cutter diameter de 483 mm 19 inches .cutter ring life

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ADVANCE RATE 3 Gross Advance Rate

The inspection time per changed cutter increases when boring in rock with lowabrasivity. This gives an increased total time per changed cutter. Time per changedcutter also depends on number of cutters changed at one time. Few cutters changedeach round gives higher unit time and may give reduced cutter life.Divided cutter rings are currently being tested in hard rock. The method may proveto be efficient. The advantage of divided cutter rings is that only the ring itself ischanged, not the complete cutter assembly. Use of divided cutter rings may resultin better working conditions reduced handling of heavy items and lower timeconsumption per changed cutter.

Other ActivitiesTime consumption for repair, maintenance and service of TBM and back-up equipment, and miscellaneous activities, is shown in Figure 2.13. The time consumptionis representative for good tunnelling practice. Time for possible main bearingfailure and other long lasting stops is not included.Miscellaneous includes the following:

- normal rock support in good rock conditions- waiting for transport- tracks or roadway- surveying, moving of laser- water, ventilation, electric cable- cleaning- other travel, change of shift, etc. .

In addition to the listed items, miscellaneous includes time loss connected to thetunnelling method and organization, and unforseen time consumption.For long headings > 8 km , miscellaneous demands an increasing part of theavailable tunnelling time. Waiting for transport will increase substantially if thecapacity of the transport system is too low.


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2. DV N E R TE

h/km ffiffi15 I- -+++-+-+-t-++-

5

2 3 Gross Advance Rate

1 2 3 4 5 6

Figure 2.13 Time consumption for other activities.

2.32 Additional Time Consumption

Net penetration rate mlhr

Estimation of time consumption for a tunnel is based on weekly advance rate,estimated on the basis of net penetration rate and total utilization. In addition, extratime must b e added for

- assembly and disassembly of TBM and back-up equipment in the tunnel- excavation of niches, branchings, dump stations etc.- rock support in zones of poor quality- additional time for unexpected rock mass conditions- permanent rock support and lining work- downtime TBM additional time for major machine breakdowns)- dismantling of tracks, ventilation, invert cleanup, etc.

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2 DV NCE R TE

4 EXAMPLE APPLICATION

Geometrical Conditions

4 Example of Application

Figure Cross section for drill and blastEquivalent cross section TBMEquivalent tunnel diameter

Geology

26 m226 1.63 = 15.9 m2

4.5 m

Figure 2.8[2.3]

Figure 2.4Figure 2.5

Tunnel length in mica schistDrilling Rate IndexDegree of fracturingAngle between tunnel axis andplanes of weakness aFracturing factor ksEquivalent fracturing factor kekv = 1.40 . 1.10

Machine ParametersTBM diameter dtbmCutter diameter deGross thrust per cutter MBCutterhead rpmNumber of cutters NtbmAvetage cutter spacing ae

Net Penetration Rate

3200 mDRI = 60

St II451.40

54

4.5 m483 mm290 kN/c rev/min307

[2.4]Figure 2.9[2.5]

Equivalent thrust Mekv = 290 . QO . 0.975 =Basic penetration ioNet penetration rate I = 8.4 . 11.1 . 60 / 1000 =

283 kN/c8.40 mm/rev5.59 m/hr

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DV N E R TE

Torque Check

2.4 Example of Application

Figure 2.12[2.7][2.6][2.8]Figure 2.7

[2.10][2.11][2.12]Figure 2.13Figure 2.13Figure 2.13

Cutter constant CcCutter coefficient kc =0.034 . 8.40jz =Necessary torque

To =0.59 . 2.25 . 32 . 290 . 0.0985 =Necessary power Po 1213 . 2 . Jt . 11.1 /60 Installed power Plbm

Gross Advance RatePenetration rate for mica schistCutter life for mica schist HCutter change and inspection tcStroke length TBM Time per regrip tlak

Machine UtilizationBoringRegrippingCutter changeRepair and service of TBMRepair and service of back up equipmentMiscellaneousTotal

0.0340.09851213 kNm1410 kW1720 kW

5.59 m/hr5.00 hrle60 minle1.83 m4.50 min

178.9 hr/km41.0 hr/km35.8 hr/km30.0 hr/km17.0 hr/km127.0 hr/km429.7 hr/km

[2.9] Machine utilization 178.9/429.7) 100 = 41.6Weekly advance ratefor 101 hr/week . 5.59 . 0.416 = 235 m

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UTT R LIF

3 CUTTER WEAR3 1 Introduction3 11 Cutter Life Parameters3 12 Cutter Ring Life

3 2 EXAMPLE OF APPLICATION

Contents

Page

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3 UTT R LIF

3 UTTER WE R

3.10 IntroductionThe cutter ring life is mainly dependent on the following factors:

3 utter ear

Rock Mass Properties Cutter Life Index CLI rock content of abrasiveminerals

Table 3 Cutter life parameters.

3.11 utter Life Parameters

Machine Parameters cutter diameter cutter type and quality cutterhead diameter and shape cutterhead rpm number of cutters

The cutter ring life in boring hours is proportional to the Cutter Life Index CLI.Figure 3 shows basic cutter ring life as a function of CLI and cutter diameter.

Correction for TBM DiameterCorrection factor for TBM diameter is shown in Figure 3.2. Centre and gagecutters have a shorter lifetime than face cutters. With increasing TBM diameter theratio of centre and gage cutters to face cutters decreases.

Correction for Cutterhead RPMCutter ring life is inversely proportional to cutterhead rpm. Correction factor forvarying cutterhead rpm is shown in [3.1].

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UTT R LIF

5 dtkRPM = RPM

dtbm = TBM diameterRPM = cutterhead rpm.

2

3 Cutter Wear

[3.1 ]

de - 48 mm

M

: ...I

I 56mm

2 4 6 8 2

Figure 3 Basic cutter ring life Ho.

Cutter life index CLI

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3 UTT R LIF 3 1 Cutter Wear

k l Flat cutterhead -

1 5

1

Dowed cutterhead

4 5 6 7 8 9

Figure 3.2 Correction factor for cutter ring life.

Correction for Number of Cutters

TBM diameter m

When the number of cutters differs from the prognosis model, the life of theaverage cutter will change. Correction for deviating number of cutters is

N tbm = actual number of cutters o = normal number of cutters Figure 2.6 .

Correction for Quartz ContentCutter ring life varies with the rock quartz content. See Figure 3.3.

[3.2]

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UTT R LIF 3.1 Cutter Wear

.

-.; ... .. - EEE=E::::E==E=::EMica schistMica gneissGneiss., , Granitic gneiss

1.4 S = S ~ I ~ . ~ : ; . Granite~ - - - l - - - ~ . ~ :. ~ ~ mg - - ~ ~ - - r - . - . _f--+---+---+:l . , _ ~ = = = : : : : ; : : : t : : : r : : t ~ = t : : : : : = t = = = : : : : : t : = : : : 1

6 . - ,; ,

4 6 8 1Quartz content,

Figure 3.3 Correction factor for cutter ring life.

The correction factor in Figure 3.3 is based on normalized field and laboratorydata. For rock types of Group the curve may be explained by the fact that CLIand rock quartz content are not independent variables.When using the prognosis model, CLI and rock quartz content should not be variedindependently. For rock types of Group one should be cautious when usingquartz content close to 0 and 27 .

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UTT R LIF

3 2 Cutter Ring LifeAverage life of cutter rings is given by [3.3] - [3.5].

3 Cutter Wear

hr/c [3.3]

H H . Im h m/c [3.4]

[3.5]

Ho basic average cutter ring lifeHh average cutter ring lifeHm average cutter ring lifeHf average cutter ring lifeI net penetration ratedtbm TBM diameter.

Ho and HI see Appendix D, page 161 expresses life of one cutter ring in theaverage cutter position ravg 0.59 . rtbm in machine hours. E.g. one ring has a lifeof 200 hours in position 12 on a 3.5 m diameter cutterhead with 26 cutters.Hh Hm and Hf expresses averaged cutter consumption for the cutterhead or thetunnel. E.g. Hm = 10 m means that for each 1 m of tunnel, the total averagedwear on all the cutters on the cutterhead corresponds to one cutter ring.

38


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UTTER WE R

3 2 EX MPLE OF PPLI TION

Machine FactorsTBM diameterDomed cutterheadCutterhead rpmNumber of cutters NtbmCutter diameter de

GeologyTunnel length in mica schistCutter Life IndexRock quartz content

Net penetration rate I

Cutter Life

3 Example of Application

4 5 m11 1 rev/min32483 mm

3200 mCLI = 20

5

5 59 m/hr

Figure 3 1Figure 3 2[3 1][3 2]Figure 3 3

Basic cutter ring life HoCorrection for TBM diameter pCorrection for cutterhead rpm kRPMCorrection for number of rings kNCorrection for quartz content kQ

7 hr1 151 001 071 22

[3 3] Hh = 107 1 15 1 00 1 07 1 22 I 32 = 5 02 hr c[3 4] Hm = 5 02 5 59 = 28 06 m c[3 5] H = 5 02 5 59 Jt 4 52 I 4 = 446 sm cPage 6 H = 5 02 32 = hr c

39


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STS ont nts

Page4 0 INTRODUCTION 414 1 NORMALIZED COSTS 42

4 10 Introduction 424 11 Costs for Assembly and Disassembly 424 12 Costs for TBM and Back up Equipment 424 13 Cutter Costs 424 14 Total Costs Behind the Face 434 15 Labour Costs 434 16 Addition for Declined Adit 434 17 Example of Application 51

4 2 TBM AND BACK UP EQUIPMENT 524 21 Depreciation 524 22 Interest 544 23 Maintenance 544 24 Downtime 544 25 Service 554 26 Electric Power 554 27 Example of Application 57

4 3 HAULING 64 30 Introduction 64 31 Track Transport 64 32 Trackless Transport 64

4 4 OTHER COSTS 664 41 Ventilation 664 42 Electrical Installations 664 43 Water Supply 66

4


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STS4 INTRODUCTION

Tunnel costs are divided into the following items:

4 0 Introduction

Main Item Assembly and disassembly2 Boring

3 Back up Equipment4 Hauling

5 Other costs

6 Labour costsTable 4 Cost items.

I Minor Item

2 TBM2.2 Cutters

4 Transport4.2 Roadway or tracks4.3 Tip5 Ventilation5.2 Electrical installations5.3 Water

Depreciation of the main equipment for tunnelling is based on the concept ofeconomic useful life. This method of depreciation is further described in ProjectReport 15A 92 HEAVY CONSTRUCTION MACHINERY Costs Performance andMaintenance. Additional equipment is depreciated partly on time and partly on use.The costs in this report are estimated in the same way as the costs in ProjectReport 3 88 TUNNELLING Costs for Drill and Blast.One should add costs for unforseen conditions during the tunnel excavation. As arule of thumb additional costs for unforseen conditions amounts to 10 of theestimated normalized costs.All costs are based on the price level of January 1994. The Department of Buildingand Construction Engineering calculates the necessary correction factors for pricelevel.

4


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4 OSTS4 NORMALIZED COSTS

4.10 Introduction

4 Normalized osts

The nonnalized costs are an evened and nonnalized summary of the detailed costanalyses given in Section 4.2 - 4.4.The nonnalized costs are mainly used for estimation of various alternatives routes,cross sections and tunnelling methods . For a more detailed cost analysis, seecomponent costs.

4.11 Costs for Assembly and DisassemblyCosts for freight, concreting of starting blocks, assembly and disassembly, andbacking the machine out of the tunnel are shown in Figure 4.1.

4.12 Costs for T M and Back-up EquipmentFigures 4.2 and 4.3 show costs for TBM and back-up equipment as a function ofTBM diameter and net penetration rate.

4.13 utter CostsBesides rings, the cutter costs include bearings, hubs and other cutter parts. Figure4.4 shows basic cutter costs COb as a function of cutter ring life and cutter diameter.Average cutter costs are calculated as follows:

N tbmcb Ob Im NOK/m[4 ]

1m = net penetration rate over the tunnelNtbm number of cutters on the cutterhead.

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4 COSTS

4.14 Total Costs Behind the Face

4 Normalized Costs

Figure 4.5 shows total costs for work behind the face as a function of T Mdiameter and tunnel length. The costs include transport of muck, ventilation,electrical installations and water supply.

4.15 abour Costs

Labour costs include all work connected to the tunnelling, including work at theadit and rig area. Hourly wages are estimated as 180 NOK/hr 50 socialsecurity costs for work in the tunnel and 140 NOK/hr + 50 social security costsfor work outside the tunnel.The following number of personnel is estimated:

TBMTransportAditRig area

31-3 track transport)2-3

T M includes TBM-operator and crew for the back-up equipment and for workbehind the face. Transport is locomotive drivers. Adit work consists of work at theadit, cutter workshop, mechanical workshop and external workers for specialwelding, electrical installations, etc. Figure 4.6 shows labour costs as a function ofnet penetration rate, tunnel length and cutter ring life.Ground support work is not included. This means ground support which requiresthe boring to be halted, i.e. grouting, assembling of segments, etc. Ground supportcarried out during boring is done by the T M crew.

4.16 Addition for Declined AditFigure 4.7 shows additional costs for declined adit length 300 m) as a function ofnet penetration rate and tunnel length.

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COSTS

engmill NOK1

8

6

4

2

4 Normalized Costs

4 5 6 7 8 9TBM diameter m

Figure 4 Costs for assembly and disassembly of T and back up equipment

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OSTS

CtbmNOKlm

10000

8000

6000

4000

2000

L

4 Normalized Costs

Im=40m hr E

4 5 6 7 8 9

Figure 4 2 TBM costs

T M diameter m

45


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4 OSTS

CbakNOKlm

2500

2000

1500

4 1 Normalized Costs

Track transport

Im=1.0m/hr Trackless I I H.. transport

: : I i i Im=1.0m/hr E

1000

500 Im=40m/hr . Im=6.0m/hr


Figure 4 3 Costs for back up equipment

46


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STS

oNOKlhr c

4 Normalized Costs

81 de 48 mm2 de =432mm3 de =356mm

6

4

H - - I - - - - t - - - ~ 2 32

2 3 4 5 6

Figure 4.4 Basic cutter costs.

Cutter life hr

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STS 4 1 Normalized Costs

1

k Track transport1 4 1 = l : H t : : : : : : : : t : ~ ~ ~ = ~ : : : : : : t ~ t1 2 _

: ; - 0 : : 8 ~ ~ : ~ : = : : = ; + ~ ~ ~ + ; ~ ~ d 7 t b B m ~ ~ = ; ~ 3 ~ ~ 5 ~ m i ~ f ~ ~ g ~ 4 ~ ~ 8 i l 1 i 2 ~unnel length km4 21 3 4 5 6Net penetration rate m/hrLt-14kmE3 LlwrlL -10kmE

- L -6km

CObsNOKlm

L 2km

-r ck transport Tracklesstransport4 5 6 7 8 9TBM diameter m

Figure 4 5 Basic costs for work behind the face Correction factor for tracktransport for net penetration rate 1m 3 m/hr [k ib] and for tunnel lengthLt 6 km [k b

48


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STS

kdl Im=6rnJhr

1.0 Im1m hr0.9

4 1 Normalized Costs

1.21.0

4m 5m 6m 7m TBM diameter, mCOInNOKlm

2I Iol , Track transport

t t:1=:;:::tt:l1 Trackless I transport I + + + + - ~ + - - ~ - ; ; : : : : : 1

2 4 6 8Cutter life, hr/c

k m ~ ~ k m H=

2 3 4 5 6Net penetration rate, mlhr

Figure 4.6 Basic labour costs. Correction factor for TBM diameter dtbm 5.5 mtrack transport [k d1 ] Correction factor for cutter ring lifeHhm 2.0 hr/c [khrl

49


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STS

5

2 I

4 6 8

4 Normalized Costs

dtbm 9m idtbm 6m tdtbm = 3m

12Tunnel length. km

Figure 4 7 Additional costs for declined adit Costs for reloading of muck in thetunnel are included in work behind the face

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STS

4.17 Example of ApplicationAverage net penetration rate for the tunnel 1mAverage cutter ring life for the tunnel Average cutter ring life for the tunnel HmTBM diameter dlbmCutter diameter deNumber of cutters NIbmTunnel length LI

4 Normalized osts

3.70 m/hr hr2.73 hr/c5.5 m432 mm4

8300 m

Figure 4.1 Assembly and disassembly 5.7 . 106/8300 = 687 NO mFigure 4.2 TBM costs = 295 NO mFigure 4.3 Costs for back-up equipment = 8 NO mFigure 4.4 Average cutter costs cb =34 . 4 3.70 = 377 NO mFigure 4.5 Costs for work behind the face

1450 . 0.97 . 1.02 = 4 7 NO mFigure 4.6 Labour costs 900 . 1.00 . 0.95 = 855 NO mFigure 4.7 Additional costs for declined adit = 43 NO m

Sum = 7 29 NO mUnforseen 10 = 7 3 NO mTotal = 7842 NOK/m

In addition corrections for efficiency factor and price increase must be made. Fordefinition of efficiency factor see Project Report 3-88 TUNNELLING Costs forDrill and Blast. Correction for price level is calculated from January 1994.

5


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4 COSTS 4.2 TBM and Back-up Equipment4.2 TBM AND B CK UP EQUIPMENT

4.21 DepreciationThe cost estimates are based on the following assumptions:

TBM diameterm3.59.5

Economiclife, tL hr1400020000

Downtime factor, k Economicuseful life, tB hr0.33

I12140

I0.33 17340

A major refurbishment or sale of the machine is presupposed at 8000 hr TBMdiameter 3.5 m and 11430 hr TBM diameter 9.5 m). Following these assumptions, undepreciated capital and assumed market value) is approximately 12 atthe time of refurbishment. For other TBM diameters, economic life is presupposedto follow a linear curve between the given values. Time for the major refurbishment is estimated at a rest remaining) value of 12 . Back-up equipment issupposed to have the same economic life as a TBM of corresponding diameter.

100R= IA4,-t 2

2boai::J>Q Refurbisment 2 ~ I

8000 t8=12140 t Machine hours, hr

Figure 4.8 Model for depreciation of TBMs. ~ =3.5 m.Costs are calculated as an average for the period until rest value of 12 isreached. The costs are based on purchase prices for TBM and back-up equipmentas shown in Figures 4.9 and 4.10.When estimating costs for a specific tunnel project, it may be necessary to calculate depreciation, interest and maintenance costs separately for that tunnel.

52


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OSTS

mill.NOK75

5

25

4.2 T M and Back up Equipment


Figure 4.9 Purchase price for TBM delivered at the site excluding investmenttax cutters and spare parts.

mill.NOK1

5Track transport I Tracklesstransport


Figure 4.10 Purchase price for back-up equipment delivered at the site excludinginvestment tax.

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STS

4.22 InterestInterest on TBM and Back-up Equipment

4.2 TBM and Back up Equipment

A real interest rate o 7 is assumed nominal interest rate corrected for inflation,etc., see Project Report 15A-92 HEAVY CONSTRUCTION MACHINERY Costs,Performance and Maintenance). The interest is calculated for the average undepreciated capital. For the period until 12 rest value is reached, the average undepreciated capital is approximately 49 . is supposed that the machine an average bores 1250 hours annually. Thismeans it will take about 6.4 years for a 3.5 m diameter TBM to reach 8 000 hours.When estimating costs for a specific tunnel jo in Norway), one should assume alower interest rate, from 5 to 7 , depending on the duration o the job.

Interest on Spare Parts is assumed that the jo site has a stock o spare parts which constitutes 12 othe depreciation basis o the TBM. Interest costs are calculated for spare parts andtwo cutter dressings price per dressing is approximately 2 o TBM price).

4.23 MaintenanceMaintenance costs include spare parts and other materials, and workshop costs forrepairs carried out at a central workshop. The fixed part o the maintenance costsfor TBM and back-up equipment is shown in Figure 4.11.

4.24 DowntimeIndirect costs for downtime are incorporated in the total utilization. Major downtime costs include inspection or failure o main bearing and axles, etc., and areestimated as 20 o the maintenance costs.

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COSTS

4.25 Service

4.2 TBM and Back-up Equipment

Service costs include materials for routine service e.g. oil change lubrication andchange of filters. Figure 4.12 shows service costs for TBM and back up equipment.

4.26 Electric PowerThe costs include the consumption of electric power. Installations cables etc. areincluded in Section 4.42 Electrical Installations.Figure 4.13 shows energy consumption for TBM and back up equipment. For highpenetration rate it may be necessary to check the curve against cutterhead torque.Cost of electric power is estimated at 0.20 NOK per kWh.

NOKlhr 1 51 0

6

4

2

2 3 4 5Net penetration rate m r-TBM

Back-upf-t- --t--4 5 6 7 8 9

TBM diameter m

Figure 4.11 Fixed maintenance costs for TBM and back up equipment. Correctionfor net penetration rate 1m 3.0 m/hr [kir]


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STS

NOKlhr200

100

4.2 T and Back-up Equipment

TBM

Back-up

4.0 5.0 6.0 7.0 8.0 9.0

Figure 4.12 Service costs for T M and back-up equipment.

TBM diameter m

4.0 5.0 6.0 7.0 8.0 9.0TBM diameter m

Figure 4 13 Energy consumption for M 90 and back-up equipment 10 .Correction for net penetration rate 1m 3.0 m/hr ~ k ]

56


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COSTS 4.2 TBM and Back-up Equipment

4.27 Example of Application - Machine Costs TBM

Assumptions see also page 51)TBM diameter dtbmTunnel length LtAverage net penetration rate 1mMachine utilization u

5.5 m8300 m3.70 m/hr41.5

Figure 4.9

Figure 4.8

a Average Costs for the First 9145 hrPurchase price TBMInvestment tax 7 Depreciation basisRest value after 9145 hr, 12 Depreciation

==

46.000 mill. NOK3.220 mill. NOK49.220 mill. NOK- 5.906 mill. NOK43.314 mill. NOK

Section 4.22 Machine hours per year 49.220 . 1 6Variable maintenance costs = _160002

Section 4.22 Average rest value

Capital Costs43.314 . 1 6

=1250 hr

1923 O lhr

48.9

Figure 4.8 Depreciation TBM 914549.220 . 106 0.07

= 4736 NOK/hr

Section 4.22 Interest TBM 489 1250 = 1348 NOK/hr

57


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STS 4.2 TBM and Back-up Equipment

Section 4.22 Interest on spare parts and cutters49.220 . 106 0.12 2 . 0.02 . 0.07 = 441 NOK/hr1250

Maintenance CostsFigure 4.11 A Fixed 4671 17 = 546

B Variable 0.1923 . 9145 = 1758 = 2304 NOK/hrSection 4.24 Major downtime, 20 of A B = 437 NOK/hrFigure 4.12 Service costs = 189 NOK/hrFigure 4.13 Electric power 1400 . 1.12 . 0.20 = 314 NOK/hr

Sum = 9769 NOK/hrAverage net penetration rate 1m = 3.70 m/hrSum = 2640 NOK/mb Cost Calculation for a Specific Tunnel New Machine

Total boring hours 8300 3 70 = 2243 hrPeriod of interest payment including assembly,disassembly and waiting for new contracts 2.0 yearsRest value after boring the tunnel

49.220 . 1 6. 13874 - 2243 2 = 34.59 mill. NOK138742

Depreciation 49.22 - 34.59 . 6 = 14.63 mill. NOK

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OSTS

Average rest value

4.2 T M and Back up Equipment

I 4 tB -t)2dtA = 0.847 . 49.22 . 106 = 41.69 mill. NOK2243 0 tB214.63 . 106

Figure 4.8 Depreciation TBM =2243

49.22 . 106 0.05 . 2.0

6522 NOK/hr

Section 4.22 Interest TBM 0 8472243

1858 NOK/hr

Section 4.22 Interest on spare parts and cutters49.22 . 0.12 2 . 0.02)_________ . 106 0.05 . 2.0

2243

Maintenance Costs

= 351 NOK/hr

Figure 4.11 A Fixed 467 . 1.17B Variable 0 1923 2243

Section 4.24Figure 4.12Figure 4.13

= 546= 431

Major downtime, 20 of A BService costsElectric power 1400 1.12 . 0.20SumAverage net penetration rate 1mSum

= 977 NOK/hr= 195 NOK/hr= 189 NOK/hr= 314 NOK/hr= 10406 NOK/hr= 3.70 m/hr= 2812 NOK/m

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COSTS4.3 HAULING

4.30 Introduction

4 Hauling

Hauling costs are estimated for track transport and trackless transport. Transport bysubcontractor is assumed for trackless transport. Required transport capacity isdefined by fully utilizing the TBM capacity.

4.31 r ck r nsportHauling costs for track transport includes

- transport of muck- rails- switches- tip costs.

TransportFigure 4.14 shows hauling costs for track transport as a function of tunnel diameter, t\.mnellength and net penetration rate. The costs are based on use of diesellocomotives.

The costs include rails, sleepers, switches, production of track sections as well asinstallation, maintenance and dismantling of the track. Rails, sleepers and switchesare depreciated partly on an annual and partly on a reuse basis. Rail costs as afunction of tunnel length and net penetration rate are shown in Figure 4.15.

Bypass StationsFigure 4.16 shows costs for necessary California Switch es as a function of tunnellength, TBM diameter and net penetration rate.


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COSTS

Rock Dump

4.3 Hauling

Figure 4 17 shows dumping costs as a function tunnel length and TBM diameterfor aboveground and underground dump stations Dumping costs include costsconnected to the rock dump The costs also include reloading and transport withdump trucks from underground dump stations

NOKlm

1000Im=2.0m/hr I=6 0rn hr I dtbm - 8m

dtbm - 6.5m dtbm - 4.5m

2

4 6 8 10

dtbm - 4 5mdillin 3m

12

Figure 4 14 Hauling costs for track transport

Tunnel length km


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STS

NOKIm200

150

100

2 4

6 8 10

4 3 Hauling

1m m hr

1m 6m hr

12Tunnel length km

Figure 4 15 Track costs including switches at the rock dump Weight of rails is5 kg/m

NOKIm

50

2

dtbm 8m dtbm=5rn

4 6 8 10 12Tunnel length km

Figure 4 16 Costs for necessary number of California Switches6


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STS

NOKlm

1800

1600dtbm 8m

1200dtbm = 6.5m

800

4

4.3 Hauling

underground station e overground station

dtbm 4.5m

2 4 6 8 12Tunnel length km

Figure 4.17 Dumping costs for track transport.

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4. STS

4.32 Trackless TransportHauling for trackless transport includes

transport of muck including dumping costs roadway turning table.

Transport

4.3 Hauling

Transport costs are based on transport by subcontractor. Figure 4.18 showstransport costs including dumping set up as a function of tunnel length and TBMdiameter.

NOK/m

4

2 4 6 8 10

dlbm 12m

dulln 10m

dtbm 8m

12Tunnel length km

Figure 4.18 Averaged hauling costs including dumping set up.


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STS

Roadway and Turning Table

4 3 Hauling

Roadway costs a function of tunnel length are shown in Figure 4 19 Costsinclude pavement grading and maintenance of drainage ditch

3

1 11 Turning table2 4 6 8 1 12Tunnel length km

Figure 4 19 Costs for roadway and turning table Trackless transport


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STS

4.4 OT R COSTS4.41 Ventilation

Other Costs

The costs include ducts duct couplings materials for duct mounting and mainte-nance depreciation and repair of fans and ducts electric power and dismantling ofthe ventilation system.Costs for filtration of air from the cutterhead are included in the back up equip-ment costs.Ventilation costs are shown in Figure 4.20.

4.42 Electrical InstallationsThe costs for electrical installations in the tunnel and at the rock dump are shownin Figure 4.21.

The costs include transformer high voltage cables materials for mounting andmaintenance of cables and dismantling of cables.Costs for transformers at the back up equipment flexicable etc. are included inthe back up equipment costs.

4.43 Water SupplyThe costs include pumps water pipes materials for mounting and dismantling ofthe installations.The costs for water supply are shown in Figure 4.22.

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STS

O lm Track Trackless

4.4 Other Costs

dtbm 9m

5

2

I I I I I I I I I I d ~ t b m ~ 3 m2 4 6 8 10 12

Tunnel length km

Figure 4 20 Ventilation costs The costs are calculated for optimal supply of freshair medium drillability and net penetration rate 1m =3 m/hr

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COSTS

NOKlm

4.4 Other Costs

2 4 6 8 1 12Tunnel length

Figure 4 21 Costs for electrical installations in the tunnel and at the rock dump

NOKlm1 Im1m/hr Im3m/hr5 1m m hr

2 4 6 8 1

Figure 4 22 Costs for water supply

Tunnel length


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TUNN LLIN ont nts

Page5.0 INTRODUCTION 75 1 CUTTERS 72

5.11 Inspection of Cutters 725.12 Changing Cutters 72

5.2 BACK UP EQUIPMENT 735.3 OTHER WORK 74

5.31 Ventilation 745.32 Electrical Installations 755.33 Water Compressed Air 75

5.4 TRANSPORT 765.40 Introduction 765.41 Track Transport 765.42 Trackless Transport 78

5.5 CREW 80

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5 TUNN LLIN

5.0 INTRODUCTION

5.0 Introduction

Work operations in the tunnel are divided into the following categories:Main Item Boring2 Back-up Equipment3 Loading, hauling

4 Other work

5 Rock supportTable 5 Activities in the tunnel.

Minor Item TBM - boring, maintenance1.2 Cutters - changing, inspection2 Operation, maintenance3 Loading3.2 Hauling3.3 Laying of tracks, track maintenance or roadway4 Ventilation - installation, maintenance4.2 Electrical installations4.3 Miscellaneous

All work operations except hauling take place near or on the TBM and back-upequipment. Problems with one type of work will easily delay the whole boringoperation.Figure 5 shows a general layout of work operations.

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c

1

1

C

lO0

:

clO

t

u1

c1lQj

>LJ:~

Fge5

T

bnGenaayowokoaofotraktranp


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5 TUNN LLIN

5 CUTTERS5.11 Inspection Cutters

5 utt rs

Inspection of cutters is carried out once or twice each shift to control the conditionof the cutters as to

- ring wear- ring slip or rings with excessive bevel edge abrasion- frozen bearings- loose bolts.

Inspection of buckets and scraper wear is carried out at the same time.

5.12 Changing CuttersChanging cutters is one of the heaviest work operations for tunnel boring. Replacement frequency per bored tunnel meter increases with increasing machine diameter.Delays due to loose bolts may occur when boring in hard and abrasive rock.The trend towards larger cutters diameter 500 mm and larger will requireincreased mechanization of cutter change operations. Increased mechanization isdesirable for

- transport of cutters to and from the face and the back-up equipment- changing of cutters at the face.

In order to ease the cutter changing operations, cutters with divided rings are beingdeveloped. For divided rings, only the ring, and not the complete cutter, is changedat the face.When designing TBMs, one should stress the cutterhead design, a high degree ofmechanization and equipment to make cutter changing easier and more effective.For tunnel projects with considerable cutter wear, it may be advantageous tochange cutters outside ordinary working hours.

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TUNN LLIN

5.2 BACK-UP EQUIPNIENT

5.2 Back up Equipment

The back-up equipment is the expression used for the system of special sectionstrailing behind the TBM itself. The main function is to carry muck from the TBMto the transport equipment and load the muck for transport out of the tunnel.A conveyor transfers muck from the cutterhead, through the back-up equipmentand loads it onto muck cars or dump trucks. As an alternative, conveyors may beused for longer transport.Besides the system for muck handling, the back-up equipment includes

- transformers- electric cabinets- cable reel- dust filters or scrubbers- equipment and systems for cutter change installation of tracks

installation of ventilation tubes installation of electric cables installation of water pipes- operator s cabin- arrangements for loading remote control, shunting system)- workshop- lunch room- optional equipment for grouting and rock support work.

Choice of back-up equipment and transport arrangements will depend on- tunnel diameter- net penetration rate- tunnel length- tunnel gradient.

Swell factor for TBM muck chips) is 1.9 - 2.0 and for drill and blast it is 1.65.Transport requirements will therefore be higher than for drill and blast tunnelling.


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5. TUNN LLIN5.3 OT R WORK

5.31 VentilationVentilation requirements are determined by

- rock drillability and mineral content- dust from the face and the conveyors- generation of heat- humidity- diesel exhaust from the transport equipment.

5 Other Work

Dust problems are reduced by water spraying and by sucking ventilation from theface, see Figure 5.2. Dry filters, water scrubbers or electrostatic filters are used forair filtration.Gas seepage from the rock may under special conditions influence the ventilationrequirements, see Section 8.1.Ventilation requirements on which the cost calculations are based Section 4.41 ,are shown in Figure 5.3. A detailed method for estimation of ventilation requirements is given in Project Report 17-91 TUNNELLING Ventilation.

Flush ingr R u b b e r dus t shield r F l ush i nq behind cut terhead

i r out le t b eh in d b ac ku pI ust f i I ters I

Workshop and backupOpera to r _ ~ Load i ng opera to r JJI J 1 t = : ; : = = V ; ~ j j ; ~ J \C II Vent i la t ion inpressure

Figure 5.2 General layout of dust suppression.

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5. TUNN LLIN 5 Other Work

4 5 6 7 8 9dtbm m

Figure 5.3 Fresh air requirements for TBM and back-up equipment.

5.32 Electrical InstallationsHigh voltage - 10 kV is conducted into the tunnel to the transformer on theback-up equipment. To ensure continuous supply of electricity the back-up equipment is fitted with a cable reel containing 300 - 400 m of flexicable. The cable isrolled out automatically with TBM advance.

5.33 Water Compressed AirWater is needed for spraying cooling and cleaning. Compressed air is needed atthe back-up equipment for drilling of bolt holes for cables ventilation tubes etc.and for tools and possible rock support work. Compressors are placed at theback-up equipment.

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TUNN LLIN

5.4 TR NSPORT

5.40 ntroduction

5 Transport

This section gives a short description of different transport systems and theimportance of the basic factors to achieve a continually high transport capacity fortunnel boring.See the supplement 1-94 HARD ROCK TUNNEL BORING Transport, for complete calculation models for transport of TBM muck. The supplement treats tracktransport use of locomotives and muck cars) and trackless transport use oftrucks). Another alternative is to use belt conveyors for transportation of the TBMmuck.

5.41 Track TransportEfficient transport operation depends on tracks of good quality. Underdimensioned,poorly laid or maintained tracks result in reduced speed and frequent derailing.Track transport operations must therefore be carefully planned. Back-up equipment,muck cars, locomotives, shunting and dumping arrangements, tracks and system forinstalling tracks, must be rational and functional.Sufficient drainage of the tunnel is maintained by minimum 0.2 incline.Installation of tracks takes place in the area between the TBM and the back-upequipment, see Figure 5.1. A crane mounted on a monorail system under the bridgeconveyor is used.Systems for track installation may vary:

- prefabricated track sections with steel sleepers and blocks of wood or steelas support, see Figure 5.4 A and C- single rails mounted on wood or steel sleepers- single rails bolted to the invert with special fastening brackets, see Figure5.4 B suitable in hard rock only, bolts are prone to loosen in medium tosoft rock)- rails mounted on concrete segments.

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TUNN LLIN 5 Transport

A

f st n ng r cket

Figure 5 4 Examples of rail fastening

Choice of track system must be adapted to the back up equipment and transportvolumes Large cross sections and/or transport demands may necessitate installationof a double tunnel trackStandard distance between rails is 900 mm Weight is 25 35 kg/m 35 kg rails arerecommended The length of rail sections is typically 6 12 mBypass stations can be

California Switch a movable bypass station running on the track build up of the invert to sufficient bypass width blasted niches


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5. TUNN LLIN

5.42 Trackless r nsport

5 Transport

The circular cross section is unfavourable with regard to trackless transport.Use of vehicles with tilted wheels enables transport to take place directly on theinvert. In weak rock wheels will gradually leave grooves in the invert causingdifficulties for the transport. This method is therefore best suited in hard rock.When using standard transport equipment the roadway may be built as a

muck roadway see Figure 5.5 double track concreted roadway concrete segment roadway.

For tunnel diameters less than approximately 8 m bypasses must be established by excavating niches filling up the invert until required width is established.

The bypasses may also be utilized as a turning place before the trucks back intothe back up equipment for loading.For tunnel diameters larger than approximately 8 m the trucks are turned using aturning table behind the back up equipment see Figure 5.6.

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TUNN LLIN 5 4 Transport

Muck

I RoadwayI~ i t heotext i le i l t r

ra i nage pipFigure 5 5 Roadway Sorted muck may be used if the rock quality is suitable

Figure 5 6 Turning table electrically and hydraulically operated79


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5. TUNN LLIN5.5 R W

The tunnel boring crew normally consists of:

5 5 Crew

Operator TBMBack-up equipmentTransport/loadingSum

12

2 - 35 - 6

person s

personsincreasing with tunnel length

Additional personnel is required for:- electrical work- cutter workshop- miscellaneous work - loading/reloading of track sections, etc. at the adit- external assistance like welding etc.

One of the members of the crew working at the back-up equipment must be amechanic. More than one of the tunnelling crew must be able to operate the TBM.This reduces the vulnerability of the tunnelling operations in cases of absence.For tunnels with systematic rock support, a larger crew will be required.


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GEOLOGY Contents

Page6 1 ROCK MASS PROPERTIES 826 2 ROCK DRILLABILITY 836 3 ROCK ABRASIVENESS 856 4 CUTTER LIFE INDEX 866 5 ROCK MASS FRACTURES 87

6 50 Introduction 876 51 Classification of Fractures 876 52 Marked Single Joints 93

6 6 GEOLOGICAL PREINVESTIGATIONS 956 60 Introduction 956 61 Engineering Geological Profile 95

6 7 CHOICE OF ROUTE 1006 8 FOLLOW UP MAPPING 1 1

6 80 Introduction 1 16 81 Cutter Consumption 1 16 82 Machine Utilization 1046 83 Use of Information 104

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6 OLO Y

6 RO K MASS PROP RTI S

6 Rock ass roperties

With regard to borability the rock mass consists of rock and planes of weakness.Rock mass properties concerning tunnel boring are described by

degree of fracturing rock drillability rock abrasiveness porosity.

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OLO Y

6.2 ROCK DRILLABILITY

6.2 Rock Drillability

Rock drillability is evaluated by the Drilling Rate Index DRI and the Cutter LifeIndex CLI. The test methods are described in the Project Report 13-90 DRILLABILITY Drilling Rate Index Catalogue.Compressive strength and point load strength are useful supplementary parameters,but are by themselves not sufficient to determine rock drillability.Porosity must be measured for rock types with porosity higher than approximately2 . The porosity s influence on the DRI is negligible. Boring in North Atlanticbasalts (Faeroe Islands) has shown that porosity has a significant influence on thenet penetration rate. A rough estimate of the influence of porosity on the penetration rate is shown in Figure 6.1. For estimation of net penetration rate, [2.3] inSection 2.21 is changed to kekv =ks-101 kOR1 kpor

4 ., ... . .- .. . : : .

.- . : :, . :.::.....,..... : / : . :

3

2:......

: : . .. . . . . . .. .. . I I......... : . .

. . .....: .. ..... ......... ::::.

1:. : : . : .. : :...

:. ::

2 4 6 8 10 12Porosity

Figure 6.1 Influence of porosity on penetration rate.Compressive strength, point load strength and shear strength are often used aspenetration rate parameters. In Figure 6.2, 80 parallel tests of compressive strengthand DRI are compared and grouped according to rock type. Compressive strengthwas measured at the Department of Geology and Mineral Engineering, NTH,following the ISRM standard. 32 mm diameter drillcores have been used.

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GEOLOGY 6.2 Rock Drillability

Figure 6.2 shows that the compressive strength underestimates the borability offoliated or schistose rocks such as phyllite, mica gneiss, mica schist, shale andgreen schist.Different laboratories measure differing values for the compressive strength forparallel tests of the same rock samples. Registered deviations have been consider-able. The deviations are caused by differences in size of samples, water content attesting and applied loading speed.

A m p h i b ~ i ti gn iss = l>iii 2III lagu 1 Greenstone

Greenschist

l>2

lagu 1001 ::;:: i m s t o n ~, : Marble

2 3 4 5 6 7 8 9 100= C:olcareous shale

2 3 4 5 6 7 8 9 1r i l l ing Rate Index ORI ri l l ing Rate I n de x ORI

Quar tz i te

Si I tstone =20 3 4 5 6 7 8 9 100

100

l>iiiagu

:1,: 0 , ::

IShale

6 7 8 9 13 4

:g 300I k f t t I t 1

1

r i l l ing Rate Index ORI ri l l ing Rate Index ORI

Figure 6.2 Relation between Drilling Rate Index DRI and compressive strength cNTH) grouped according to rock type.84


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6 GEOLOGY6 ROCK R SIVENESS

Cutters with Carbide Inserts

6 3 Rock Abrasiveness

Rock abrasiveness on carbide inserts is expressed by the Abrasion Value AV

Cutters with Steel RingsRock abrasiveness on ring steel is expressed by the Abrasion Value Steel AVSAV and AVS are described in the Project Report 13 90 DRILLABILITY DrillingRate Index Catalogue

50cE -EV 4> III I II

QJ _ . : : rI/ _In0 II::i IIto . . CI< 1Iluf

Figure 7.2b Typical chip shapes and crack patterns for various rock types.108


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ORING PRO ESS

Chipping displays the following main tendencies:

7 1 Chipping

Rocks with high brittleness have most crack formation and chipping tothe sides.Rocks with medium to low brittleness have less crack formation andchipping. The chips are thicker and have a distinct and curved chippingcrack .Rocks with high surface hardness low SJ) have particularly thin andlong chips. The cutter edge rolls on the surface without indention.Rocks with low surface hardness high SJ) have a lot of crushed rockpowder in the cutter grooves and comparatively thick and rectangularchips not shown in Figure 7.2).Increasing thrust results in thicker and more rectangular chips.In fractured rock, chips are more cubed, since one or more of thechipping planes are fissure or joint planes.It s the chip shape, and not s previously assumed the chip size, whichreveals the efficiency of the chipping mechanism.

The cutter edge indention determines the depth of the crack formation into the rockface, and thus how efficient the chipping will be.

DR I = 445J = 52 =

DRI = 44 J = 752 = 45

Figure 7.3 Importance of indention depth on crack formation, chip thickness andshape.

The fundamental relations between drillability parameters and machine factors forefficient chipping, are shown in Figure 7.4.

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ORING PRO ESS 7 hipping

cucoc..tilL1.- JU

r i t t Ieness

ucoc..coutil JL

urface hardness

Figure 7.4 Fundamental relations between drillability parameters and machinefactors.

Since the indention, ip so important for the chipping, drillability parametersshould include rock resistance to indention.The Drilling Rate Index DRI an indirect measure for the required boring work,where:

the brittleness value expresses the amount of energy required to crushthe rockthe Siever s J-value expresses the depth the cutter can be thrust into therock; in other words how efficiently the rock brittleness crackingtendency) can be utilized.

For more information on material properties for TBM chips, see Project Report16-91 TBM MUCK Properties and Utilization in Norwegian only).110


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7 ORING PRO ESS 7 Machine Factors Affecting Performance

7.2 MACHINE FACTORS AFFECTING PERFORM N E7 21 Thrust - Penetration Curves

Gross ThrustGross average thrust per contact point is gross machine thrust divided by numberof contact points cutter discs or carbide insert rows).Gross thrust includes friction of the cutterhead, loss of hydraulic pressure in pipesetc. during boring. Normally this makes up approximately 10 High cutterheadside support pressure against the tunnel wall may increase the friction considerably.This occurs generally when boring in sharp curves and during the training periodfor new operators. Towing of the back-up equipment during boring will also reducethe thrust.The constantly varying surface of the rock face fractures, mixed face, etc.) willresult in an uneven distribution of the total thrust on the different cutters. Themomentary load on a single cutter may be up to 10 times the average load seeFigure 7.8). The load is also unevenly distributed on the centre, face and gagecutters normally lowest in the gage).Planes of weakness in the rock mass and mixed face produce heavy impacts on thecutterhead and vibrations in the machine. To avoid damage to machine and cutters,the available machine thrust capacity can not always be utilized.The trend in recent years has been use of larger cutters and increased thrust percontact point. Maximum average thrust is limited by the life of cutter bearings,ring steel hardness and sufficient ring fastening to hubs. Gross thrust can also belimited by the ability of the machine s main bearing to carry the cutting loads andoverturning moments from steering and boring in rock layers of different hardness.

Penetration CurvesThrust level and cutter spacing must be adapted to rock properties to achieveefficient chipping. The relation between penetration and gross thrust per contactpoint is shown in Figure 7.5.

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ORING PRO ESS 7 Machine Factors Affecting Performance

f the gross thrust is very low, the cutters will roll and wear against the rock facewith low penetration and high cutter costs as a result.

col

QcQ

cQa

-Gross thrust per cutter discFigure 7.5 Penetration curve.

The penetration curve will be moved upwards and have a lower penetrationcoefficient b in a fractured rock mass - depending on the degree and orientation offracturing, see Section 7.3.The curves may level out somewhat for high thrust levels. Limitations are e.g. thatcutters butt with their hubs , insufficient muck removal from the invert, blockingof cutterhead buckets in rocks with high SJ or rocks with high clay content orother weak minerals, or extremely good chipping. Extremely good chippingproduces an uneven rock face with heavy vibrations in the TBM as a result.

Penetration Curves - Linear Test Rigs vs TBMPenetration tests with linear test rigs in laboratories show that required gross thrustfor chipping is proportional to the contact area Ac under the cutter edge. Thefollowing formula applies to cutters with a constant cross section:

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BORING PROCESS 7 Machine Factors Affecting Performance

M =B r 1e 0 kN/c [7.1]

1 =o mm1rev [7.2]

O e = rock compressive strengthbe = cutter edge widthre = cutter radiusM 1 = critical thrust necessary thrust to achieve 1 mm1rev .

Results from linear test rigs can be compared directly with tests on a Mobile Minerwith linear cutter action. A direct comparison between linear test rigs and circulartunnel boring is not possible due to the variation of the penetration coefficient b forT boring.The penetration coefficient b is the factor in the prognosis which represents thechipping frequency, in other words how many times the cutterhead rotates before atotal chipping has occurred at the face, see Figure 7.6.

Chips from first passing< J Chips from second passing

Figure 7.6 Chipping at the face.113


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7. ORING PRO ESS 7 Machine Factors Affecting Performance

For tunnel boring, the penetration coefficient implies:b =2.0 An average total chipping at the face per revolution of the cutter-

head.b < 2.0 The cutters break chips greater than the cutter spacing double

chipping). In principle, the spacing should be increased.b > 2.0 The cutterhead rotates several times before a total chipping at the

faee has occurred. In principle, the spacing should be decreased.

7.22 utt r EdgeCutter rings are given different shapes as shown in Figure 7.7.

Figure 7.7 Cutter rings with wedged and constant cross section design.

The shape of the cutter edge affects boring performance:Wedged rings give high penetration rate long as the edge is sharp.Penetration rate drops rapidly with edge bluntness. Edge bluntnessreduces cutter indention due to increased edge width.Constant cross section rings give more even penetration rate over thering life.

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ORING PRO ESS 7 Machine Factors Affecting Performance

The penetration rate prognosis is based on an average cutter bluntness.In abrasive rock with low SJ, cutters must be replaced very frequently. The cutteredge will be worn down to a flat shape and not to the normal rounded shape. Thisresults in lower penetration rate than expected due to an inevitable lag in cutterreplacement.Cutters with carbide inserts may be used under such conditions. Cutter replacementwiHthen be reduced. The breaking edge of the cutter, i.e. the carbide inserts, willpreserve their shape and give better penetration rate over the cutter life.Cutter wear forms are described in Section 7.4.

7.23 orque emandRequired torque to rotate the cutterhead depends on:

- cutterhead diameter- number and position of cutters- gross thrust per cutter- cutter coefficient.

Cutter coefficientThe cutter coefficient kc is the ratio between gross drag force and gross thrustforce MBon the cutter see Figure 7.8 . The cutter coefficient depends on:

- type of cutter diameter and edge shape- cutter spacing- indention depth- skidding- degree of fracturing- cutterhead shape.

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ORING PRO ESS 7 2 Machine Factors Affecting Performance

Ma =gross thrust capacity

Ma = gross thrust capacity

eSa =gross drag force

Irc I rc - Ip I I -77/----,=- 7>.,..- 7 77 - - - I

- - + - : : : : : . . . 7 7 / - - - - , = - 7 > , . . . . - - ~ - 7 7 7 _ _ _ _ , . ~ + i p

Ra = gross resultant force

eSa = gross drag forceJ1

/ 0 I I

I I--,.,.,..- 777-77/----,. ,.....:.:>


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ORING PRO ESS 7 2 Machine Factors Affecting Performance

The cutter coefficient is in principle the rolling resistance of the cutter. Therolling resistance is obtained by moment equilibrium for the cutter bearing axle.

k =c /2 r i= V c p 2 1p = t n o [7.3]

The indention depth ip cannot be measured. When normalizing data the penetrationio must be used and the constant Cc or c estimated.

k = tanl; c . tancoc

which can be simplified to:

r i ic . tan atanV or ic 0

/2 . rc 10k = c i _ _e rc [7.5]

The orientation of weakness planes also affects the cutter coefficient - although toa smaller extent.Worn down cutters will give a somewhat higher coefficient due to reduceddiameter and the tendency to create deep grooves before chipping. In extremecases the cutter may butt with its hub and thus increase the coefficientdramatically.

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ORING PRO ESS

Torgue Demand

7 2 Machine Factors Affecting Performance

Torque demand is found by the following formula:

N NT = Lr i S i = Lri MBi kci [7 6]

= 0.59 . r N . M . ktbm Ibm B c kNm)

The factor 0.59 . rlbm is the position for the average cutter on the cutterhead. Thefactor may be calculated when the cutterhead design of a machine is known.Required power installation is found by:

T . 2 . t . RPMp = 60 kW) [7 7]

Most machines are designed for a cutter coefficient of kc =0.10 0.02 at maximum thrust capacity.f more torque is required, the voltage from transformers can be increased. Thisresults in increased strain on electric motors when starting up. n increase involtage must therefore only be done after consultation with machine manufacturerand electrotechnical experts. For 380 V motors, the torque increases with the ratio:

U 2Tk = ----) . To380 kNm) [7.8]

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ORING PRO ESS

7.24 utterhead RP

7 Machine Factors Affecting Performance

Cutterhead rpm is approximately constant for machines with electric motors. Themachines are designed with a fixed and very high reduction in gear boxes and ringgears. Some machines are designed with rpm regulation variable frequency drive .Choice of cutterhead rpm depends on:

- main bearing life- cutter bearing life determined by gage cutter rpm- limitations as to installed power lack of space on small diameter machines- vibration level on machines with rpm regulation.

Cutterhead rpm has been undergoing a rapid development as new machines havelarger cutters, increased peripheral speed and increased power installation.Field studies show that penetration per revolution is nearly independent of cutterhead rpm, as long as the rpm is within reasonable limits.

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ORING PRO ESS

7 BORING IN FRACTURED ROCK MASS7.30 Introduction

7 3 Boring in Fractured Rock Mass

Net penetration rate increases when boring in fractured rock mass. The additionalpenetration due to fracturing is not only dependent on rock conditions but on theTBM as well.Chipping mechanisms for boring in fractured rock mass vary with type of discontinuities i.e. whether they are marked single joints or systematical planes of weakness. The prognosis for boring in fractured rock mass is based on extensive recordsfrom tunnel projects mainly in Norway but also in other countries.

7.31 Marked Single JointsA typical progress for boring through a marked single joint is shown in Figure 7.9.

LA A A A

Void area

Station no 1420kN/cutter

1430----

1440u t n f

m r

Figure 7.9 Penetration rate progress for boring through a marked single joint.

Net penetration rate increases until section A-A where the void area is largestand decreases towards the end of the joint. Penetration rate increase is caused byan unevenly broken face. Fall-outs along the joint plane leaves a void area in the

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7 ORING PRO ESS 7 Boring Fractured Rock Mass

face see Figure 7.10 . The void area is largest at section A-A where the extent ofthe joint equals the tunnel diameter. The void area implies that a few cutters losecontact with the face, and therefore cannot take any load. This load is transferredto cutters still in contact with the face, thus increasing the effective thrust for these.Penetration curves show that penetration rate increases with increasing thrust.The addition in penetration due to jointing is approximately proportional to thevoid area in the face. The void area can be estimated and used when normalizingpenetration rate data.

Figure 7.10 Void area formed by a fall-out from the face along a joint inamphibolitic schist.

more than one single joint occurs at the same time, the total effect must beestimated and overruled by judgement, see Figure 7.11. The TBM will in suchzones often be torque limited. Thrust is kept more or less constant when the jointis met until the machine vibrates excessively or is torque limited. Thrust is thenreduced, and increased again when the joint is disappearing.

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7 ORING PRO ESS 7 3 Boring Fractured Rock Mass

From mapping

Measured in tunnelm/hr _

Figure 7 11 Penetration rate progress for boring through more than one single joint

The length of a single joint along the tunnel increases linearly with TBM diameterThus larger machines utilize the advance addition over a longer distance

7 32 Prognosis for rked Single JointsThis specific model is based on a small number of observations The theoreticalpenetration addition is shown in Figure 7 12 Normalized penetration addition isshown in Figure 7 13

oR

1 / \-oo

Angle between tunnel axis and single joint

Figure 7 12 Theoretical progress for averaged penetration addition for markedsingle joints

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ORING PRO ESS 7.3 Boring in Fractured Rock Mass

c:o0g 30c:o:;:;c:

Q

10

10

DRI=40

30

. DRI=45

4 50

DRI=50

60Angle between tunnel axis and planes of weakness, a

Figure 7.13 Average penetration addition for marked single joints.

Example of ApplicationZone with equal DRINet penetration rate for the zoneTunnel length of marked single joints

600 m3.78 m/hr150 m

Average net penetration rate f

04_NTH_Project Report 1-94 Hard Rock Tunnel Boring

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