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PROYECTO HIDROELECTRICO ALTO MAIPO

INGENIERIA BASICA

GENERAL SPECIFICATIONS FOR TUNNELLINGAND ROCK SUPPORT

0 19-12-08 PARA LICITACION

EMISION FECHA PROPOSITO DE LA EMISION PREPARA REVISOCOORDINADOR

GENERAL APROBO

D. PROYECTO/ D. ADJUNTO

APROBO

SUBGERENTEDE INGENIERIA

APROBO

GERENTE DEPROYECTO APROBO

REVISION

1

N°: 600-TU-ETG-001

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600-TU-ETG-001i

INDEX

ITEM CONTENTS PÁG.

1. Drilling of holes, exploratory drilling and grouting ................................................. 1

1.1 Scope .................................................................................................................. 1

1.1.1 Coverage ............................................................................................................. 1

1.2 Classification and Definition ................................................................................. 1

1.3 Reference Standards ........................................................................................... 1

1.4 Submissions by the Contractor ............................................................................ 1

1.4.1 Documents........................................................................................................... 2

1.4.2 Test Reports ........................................................................................................ 2

1.5 General ................................................................................................................ 2

1.6 Equipment and Execution .................................................................................... 3

1.6.1 Exploratory Drilling and Grouting ......................................................................... 3

1.6.2 Holes for other Purposes ..................................................................................... 4

1.6.3 Drilling Accuracy: ................................................................................................. 5

1.6.4 Deviation Measurements of Drill-holes ................................................................. 5

1.6.5 Water Pressure Tests .......................................................................................... 5

1.6.6 Flushing between holes ....................................................................................... 5 1.6.7 Grouting ............................................................................................................... 6

1.7 Logging of drill holes ............................................................................................ 7

1.8 Water Pressure Testing ....................................................................................... 8

1.9 Grouting ............................................................................................................... 8

1.9.1 Grouting Materials ................................................................................................ 8

1.9.1.1 Water ................................................................................................................... 8

1.9.1.2

Cement ................................................................................................................ 8

1.9.1.3 Admixtures ........................................................................................................... 9

1.9.1.4 Chemical grouts ................................................................................................. 10

1.9.2 Cement Grouting above ground ......................................................................... 10

1.9.3 Cement Grouting underground ........................................................................... 11

1.9.4 Chemical Grouts ................................................................................................ 12

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1.9.5 Filling of Cavities with Concrete or Mortar (Consolidation grouting) ................... 12

2. Rock Excavation ................................................................................................ 13

2.1 Scope and definitions ......................................................................................... 13

2.1.1 Coverage ........................................................................................................... 13

2.1.2 Classification and Definition ............................................................................... 13

2.1.2.1 General .............................................................................................................. 13

2.1.2.2 Rock Mass Quality Classification ....................................................................... 14

2.2 Submittals by the Contractor .............................................................................. 14

2.2.1 General .............................................................................................................. 14

2.2.2 Documents for submittal-Rock excavation ......................................................... 15

2.2.3 Test Reports ...................................................................................................... 15

2.2.4 Documents for submittal-TBM excavation .......................................................... 16 2.3 Rock Excavation ................................................................................................ 17

2.3.1 General Requirements ....................................................................................... 17

2.3.2 Ventilation .......................................................................................................... 20

2.3.3 Illumination, Communication and Roadways ...................................................... 21

2.3.4 Survey ............................................................................................................... 21

2.4 Open Cut Excavation ......................................................................................... 22

2.5 Underground Excavation .................................................................................... 22

2.6 Drilling and Blasting (Above- and Underground) ................................................ 23

2.6.1 General .............................................................................................................. 23

2.6.2 Excavation Tolerances ....................................................................................... 23

2.6.3 Drilling Accuracy ................................................................................................ 24

2.6.4 Perimeter Blasting .............................................................................................. 24

2.6.4.1 General .............................................................................................................. 24

2.6.4.2 Smooth Blasting ................................................................................................. 24

2.6.4.3 Pre-splitting ........................................................................................................ 25

2.7 Drilling and Reaming of Shafts by raise-boring machine (RBM) ......................... 25

2.8 Tunnel excavation by tunnel boring machine (TBM) ........................................... 25

2.8.1 General .............................................................................................................. 25

2.8.2 Requirements to TBM machines ........................................................................ 26

2.8.3 Backup system .................................................................................................. 28

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2.8.4 Exploratory drilling, grouting and rock support ................................................... 28

2.8.5 Invert concrete segments ................................................................................... 29

2.8.6 Assignment of risk during TBM excavation......................................................... 29

2.9 Utilisation of Materials ........................................................................................ 30

3. Rock Support ..................................................................................................... 30

3.1 Scope ................................................................................................................ 30

3.1.1 Coverage ........................................................................................................... 30

3.1.2 Classification and Definition ............................................................................... 31

3.1.2.1 General .............................................................................................................. 31

3.1.2.2 Rock Mass Quality Classification ....................................................................... 31

3.1.2.3 Rock Support Classification ............................................................................... 31

3.2 Reference Standards ......................................................................................... 33 3.3 Submissions by the Contractor .......................................................................... 33

3.3.1 General .............................................................................................................. 33

3.3.2 Documents......................................................................................................... 33

3.3.3 Test Reports ...................................................................................................... 34

3.3.4 Certificates ......................................................................................................... 34

3.4 General .............................................................................................................. 34

3.4.1 Inspection of Tunnels, Marking of Chainage, Wash-down .................................. 34

3.4.2 Rock Support ..................................................................................................... 35

3.5 Scaling ............................................................................................................... 36

3.5.1 General .............................................................................................................. 36

3.5.1.1 Basic Scaling ..................................................................................................... 37

3.5.1.2 Additional Scaling .............................................................................................. 37

3.6 Rock Bolts and Accessories ............................................................................... 38

3.6.1 Materials ............................................................................................................ 38

3.6.2 Accessories ....................................................................................................... 39

3.6.3 Execution ........................................................................................................... 40

3.6.3.1 Drilling and Installation of Resin End-anchored Bolts ......................................... 40

3.6.3.2 Drilling and Installation of Fully Cement-grouted Bolts ....................................... 40

3.6.4 Testing ............................................................................................................... 41

3.6.4.1 General .............................................................................................................. 41

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3.6.4.2 Criteria for Assessment of Test Numbers and Acceptance of Test Results ........ 42

3.6.4.3 Measures to be taken in Case of Rejection and Re-bolting ................................ 42

3.7 Spiles ................................................................................................................. 43

3.8 Rock Anchors .................................................................................................... 43

3.9 Sprayed Concrete .............................................................................................. 44

3.9.1 General .............................................................................................................. 44

3.9.1.1 Composition ....................................................................................................... 44

3.9.1.2 Requirements for Sprayed concrete ................................................................... 46

3.9.1.3 Methods/Execution ............................................................................................ 46

3.9.1.4 Thickness .......................................................................................................... 47

3.9.1.5 Testing and Control ............................................................................................ 47

3.9.1.6 Documentation ................................................................................................... 48 3.9.1.7 Reinforcement of Sprayed Concrete .................................................................. 48

3.9.1.8 Method/Execution .............................................................................................. 49

3.10 Cast in place Concrete Rock Support ................................................................ 50

3.10.1 Scope ................................................................................................................ 50

3.10.2 Materials/Equipment .......................................................................................... 50

3.10.2.1 Materials and Admixtures for Concrete .............................................................. 50

3.10.2.2 Reinforcement (if applicable) ............................................................................. 51

3.10.2.3 Concrete Grade and Strength Requirements ..................................................... 51

3.10.2.4 Methods/Execution ............................................................................................ 51

3.10.3 Tolerances ......................................................................................................... 52

3.10.4 Testing and Control ............................................................................................ 52

3.10.4.1 General .............................................................................................................. 52

3.10.4.2 Production Control ............................................................................................. 52

3.10.4.3 Materials Control prior to Concreting .................................................................. 52

3.10.5 Documentation ................................................................................................... 53

4. Investigation and Instrumentation during construction ........................................ 53

4.1 Scope ................................................................................................................ 53

4.1.1 General .............................................................................................................. 53

4.1.2 Coverage ........................................................................................................... 54

4.2 Reference Standards ......................................................................................... 55

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4.3 Submittals by the Contractor .............................................................................. 55

4.3.1 Documents......................................................................................................... 55

4.3.2 General .............................................................................................................. 56

4.3.3 Core Drilling and Water Pressure Testing .......................................................... 56

4.3.3.1 General .............................................................................................................. 56

4.3.3.2 Drilling Equipment .............................................................................................. 57

4.3.3.3 Core Boxes ........................................................................................................ 57

4.3.3.4 Measuring Equipment ........................................................................................ 58

4.3.3.5 Water Pressure Testing ..................................................................................... 58

4.3.3.6 Calibration Procedure ........................................................................................ 59

4.3.3.7 Programme of Work and Number and Position of Boreholes ............................. 59

4.3.3.8 Drilling ................................................................................................................ 59 4.3.3.9 Handling and Storage of Core Samples ............................................................. 61

4.3.3.10 Inclination and Orientation of Boreholes ............................................................. 62

4.3.3.11 Backfilling .......................................................................................................... 62

4.3.3.12 Record of Operations ......................................................................................... 63

4.3.4 Services for Rock Mechanical Testing and Rock Stress Measurements ............ 64

4.3.5 Convergence Stations ........................................................................................ 64

4.3.6 Piezometers ....................................................................................................... 66

4.3.7 Surface Settlement Monuments and Fixed Points .............................................. 66

4.3.8 Joint Deformation Meters ................................................................................... 67

4.3.9 Ground Water Monitoring ................................................................................... 67

4.3.10 Materials ............................................................................................................ 67

4.3.11 Measuring Range............................................................................................... 67

4.3.12 Accuracy and Resolution ................................................................................... 67

5. Pavement in Water Tunnels ............................................................................... 68

5.1 Specifications ..................................................................................................... 68

5.1.1 Pavement in the access tunnel .......................................................................... 68

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List of tables

Table 1-1: Submittal of documents – Drilling of holes ............................................................. 2 Table 1-2: Submittal of test reports – grouting ........................................................................ 2 Table 2-1: Documents for submittal – Rock excavation ........................................................ 15 Table 2-2: Documents for submittal – Blasting tests ............................................................. 16 Table 2-3: Documents for submittal – TBM excavation ......................................................... 16 Table 2-4: Limits for peak particle velocity ............................................................................ 19 Table 2-5: Limits for toxic gas levels ..................................................................................... 20 Table 2-6: Drilling accuracy .................................................................................................. 24 Table 3-1: Submittal of documents- Rock Support ................................................................ 33 Table 3-2: Submittal of test reports – Rock support .............................................................. 34 Table 3-3: Test frequency ..................................................................................................... 53 Table 4-1: Submittal of documents – Investigation and instrumentation ................................ 56 Table 4-2: Tolerances ........................................................................................................... 60

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600-TU-ETG-0011

1. DRILLING OF HOLES, EXPLORATORY DRILLING AND GROUTING

1.1 Scope

1.1.1 Coverage

This Chapter specifies requirements for drilling of holes for ground water controlsystems and all exploratory drilling, water pressure testing and grouting in order to explore andmodify the properties of the ground on or through which the Works are to be constructed. Theextent of such work depends on the properties of the soil and rock encountered during theprogress of the Works and shall be carried out as directed by Gener.

1.2 Classification and Definition

Definition of grouting at the face and grouting behind the face shall be similar to

the corresponding definition of support work in Chapter 3.1.2 Classification and Definition, underdefinition of “Support work at the face” and “Support work behind the face”.

1.3 Reference Standards

The work shall be performed according to relevant standards, or if no standardsexist, the work shall be performed according to recognised practice approved by Gener.

1.4 Submissions by the Contractor

Submissions that the Contractor is required to make to Gener are describedbelow.

The issue time defines the date that Gener shall receive the first issue of thedocuments:

XF = X number of weeks prior to start of manufacture/work as applicable.

XT = X number of weeks after completion of test/inspection/work as applicable.

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600-TU-ETG-0012

1.4.1 Documents

The Contractor shall prepare and submit documents in accordance with Table1-1.

Table 1-1: Submittal of documents – Drilling of holes

Documentation Issue forapproval

Issue forinfo

Issue time

Organisation plan for the Works showing procedures andmaterials for the work and the responsibilities andqualifications of the personnel.

* 6F

Log of all drilled holes. * 1T

Specific grouting procedures, material, composition,properties and equipment.

* 6F

Gener ’s approval does not relieve the Contractor of his sole responsibilities forefficient and successful execution of the work.

1.4.2 Test Reports

The Contractor shall make tests and prepare and submit test reports inaccordance with Table 1-2.

Table 1-2: Submittal of test reports – grouting

Item Issue forapprovalIssue for

info Issue time

Characteristics of grout agents * 6F

Characteristics of packers and flexible hoses * 6F

1.5 General

Drilling of holes for exploratory drilling, ground water control and rock massgrouting encompasses:

Drilling of vertical and inclined holes from surface for rock mass grouting in damfoundation and control of ground water in areas as defined by Gener.

Drilling of holes for exploratory drilling and grouting from surface, from any tunneland cavern-front or from elsewhere in the underground openings at all angles as instructed byGener.

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600-TU-ETG-0013

Grouting works will be performed in underground constructions for control ofpermeability, for consolidation and as contact grouting around or in structures in undergroundopenings.

Grouting may be done either as cement grouting or as chemical grouting.

Grouting operations are not designed and specified in detail at the tender stage.The grouting works will be decided and designed by Gener in co-operation with the Contractorduring excavation.

The Contractor shall at any time during the progress of the Works provide andmaintain adequate equipment and materials with stand-by reserves to be able to carry out anydrilling and grouting operation covered in the specifications.

The grouting shall be supervised by an engineer with documented grouting anddrilling experience from similar works. At least one additional crew member shall documentappropriate experience.

The Contractor shall keep daily updated records and logs of all drilled holes,flexible grouting tubes, water pressure tests and grout takes. The results shall be presented innumerical and graphical format, comprising every borehole and every flexible tube with resultsof water pressure tests, grout takes at the various depth intervals, and data for performance andapplied pressures. The boreholes and tubes shall be given a number, identifying location aswell as direction.

1.6 Equipment and Execution

1.6.1 Exploratory Drilling and Grouting

Percussion drilling equipment shall be used for drilling of exploratory drillholes,grouting holes, control holes, sounding holes, and drainage holes etc. in rock and concrete bothabove- and underground, if not otherwise requested by Gener.

Percussion drilling equipment shall be capable of drilling holes up to 50 m lengthin any direction. Percussion drilling equipment shall be available from start of excavation work.

Bits with a minimum diameter of 45 mm shall be used for drilling.

Core drilling equipment shall be available as specified in Chapter 4 Investigationand Instrumentation during construction.

Equipment units for excavation and rock support work may be used whensatisfying the above requirements.

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600-TU-ETG-0014

Water flushing shall be used during drilling of all grout holes. The use of greaseor lubricants on drill rods or use of mud for drilling is not permitted.

After drilling, the hole shall be flushed with water and air. Pumps for supply of airand water for flushing shall be capable of delivering a pressure of minimum 10 bar.

The tolerance for collaring of drill holes is 0.10 m measured from theoreticalpattern and for alignment deviation the tolerance is 4% of the depth of the hole.

All drillholes shall be grouted with non shrink mortar unless otherwise ordered byGener.

Drillholes for grouting in soil shall be of the rotary type with casing, minimumdiameter 76 mm.

1.6.2 Holes for other Purposes

The purpose of drilling is indicated under the payment items in the PaymentSchedules.

The method of drilling is the choice of the Contractor. The diameter of the hole isthe choice of the Contractor, if not specified. The Contractor shall be able to drill long holes inall directions and within the drilling accuracy specified. Steering rods and special bits may berequired in order to fulfil these requirements. Efficient equipment is required in order to securean adequate advance according to the time schedule.

The drillholes shall be equipped with permanent casing down to minimum 5 minto unweathered rock. The casing shall be supplied with threaded end and transition reducerfor connection of specified size water pipes and valves. Casing and transition reducer shall behot dip galvanised. The inner diameter of the casing shall be equal to any specified holediameter. The transition between casing and rock shall be watertight in order to avoid that waterclose to the surface or tunnel contour may leak into the drill hole. After drilling, the hole shall beflushed with water and air. Pumps for supply of air and water shall be capable of delivering apressure of minimum 10 bar. The Contractor shall prepare a procedure for sealing and cleaningof drill holes. The procedure shall be approved by Gener prior to commencement of Work.

Packers for water pressure testing and grouting shall be available for all drill holediameters.

All relevant field observations and measurements shall be logged.

Ground water monitoring shall be performed. Ground water levels shall berecorded twice a shift for each hole during drilling operation.

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600-TU-ETG-0015

1.6.3 Drilling Accuracy:

Collaring = 0.10m

Maximum deviation = 4% of drilled length

No drill hole shall come closer than 15m to tunnels and caverns if not otherwisespecified or instructed by Gener. If deviation measurements indicate that the hole is closer than15m to tunnels and caverns, the hole shall be filled with expanding mortar and replaced withnew holes at the expense of the Contractor.

1.6.4 Deviation Measurements of Drill-holes

See Chapter 4, Investigation and Instrumentation during construction.

1.6.5 Water Pressure Tests

The Contractor shall keep adequate stock of all types and dimensions of packersconsidered necessary from start of underground excavation work. The packers shall be ofproven types, designed for expansion either mechanically or by other approved means (e.g.hydraulically). Packer function shall be verified by testing in steel pipe at surface prior to use inboreholes. Pneumatic packers will not be accepted.

After expansion, packers shall provide an impermeable seal for pressurised waterand - if required - later grouting in any position with pressure as defined for grouting equipment.

Packers shall be equipped with a valve to allow sealing of the hole at the end of the groutingprocess.

Single packers shall be used for testing in stages during drilling. Double packersshall be used for testing after completion of drilling. Double packer separation shall be adjustedto local rock mass conditions.

Pressure gauges and pumps for water pressure tests shall conform to specifiedrequirements given in Chapter 4, Investigation and Instrumentation during Construction.

1.6.6 Flushing between holes

If flushing between holes is required, the Contractor shall have available a highcapacity water pump (min 200 l/min.at 50 bar), air compressor and other equipment (radialflushing head) needed for efficient flushing operation.

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600-TU-ETG-0016

1.6.7 Grouting

Equipment both for cement grouting and chemical grouting shall be available andin working order at any time at the site.

Each unit of equipment for cement grouting shall include, but are not limited to:

Grout mixer

Grout agitator

Grout pump

Flow meter, pressure gauges for air, water and grout supply lines, grout supply,valves, packers and fittings to supply a continuous flow of grout and an accurate pressurecontrol

The Grout Mixer shall be a high-speed colloidal grout mixer. The mixer shall becapable of mixing grouts with water/ cement ratios between 0.4 and 10. An accuratemeasurement of materials shall take place at the mixer so that mix proportions can be exactlycontrolled. Cement may be added to the mixer by weight or by volume. Each componentadded to the mixer shall be measured to an accuracy of +/- 5 %. Minimum mixer capacity shallbe 250 l.

The Grout Agitator shall be capable of keeping grout of specified water-cementratios (between 0.4 and 10) in suspension. It shall be equipped with screen to remove particlesnot passing a 4.75 mm sieve. The sump shall be graduated to metric standards so that thevolume of grout injected into a hole can be measured accurately. The capacity of the agitator

shall not be less than twice that of the mixer.

The grout pumps shall be a progressive cavity, pulse free type, capable ofhandling thin and viscous grouts with no pulse. The capacity shall be at least 0.08 m 3 grout perminute at a discharge pressure of 50 bar, and minimum 0.05 m 3 per minute at 100 bar. Thepump shall be equipped with a pressure regulating device securing a maximum groutingpressure within ± 10 % of the required pressure. The grout pumps shall be able to operate withworking pressure of at least 120 bar. Pressure gauges shall be Bourdon type or similar of heavyduty quality and shall measure pressures as appropriate to the range of grouting pressureemployed. Two pressure gauges shall be supplied for the grouting plant, one at the header and

one at the pump. In addition a pressure recording unit shall be connected to the pressure linefrom the grout pump. The dial size of the pressure gauge shall not be less than 150 mm. Thepressure recording unit shall record the pressure within ±1 bar. The records may be in analogueor digital form and with the possibility of pressure readings every minute. The Contractor shallsupply a calibrated master gauge for each pressure range for checking the accuracy of allgauges used.

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600-TU-ETG-0017

The pump and the connected agitator shall be located at a distance of maximum30 metres from any hole being grouted.

Packer dimension and construction of the packer shall correspond to the diameterof the drill hole, to the drilling method used to produce the hole, and to the applied pressure.Double packers and single packers shall be available. Disposable packers may be used ifapproved by Gener.

For chemical grouting, suitable pumps as well as necessary accessories shall beavailable. Required working maximum pumping pressure is 250 bar. Equipment shall becompatible with grout data as given by manufacturer. Pumping capacity shall as a minimum be4 l/min.

All grouting units shall at all times be clean and in proper working condition. TheContractor shall supply sufficient operating personnel, supervision, labour, spare parts and toolsto operate the units at full capacity and top efficiency. A minimum of three grouting units of eachtype shall be available at site.

The grouting plant shall be provided with satisfactory storage for supplies ofgrouting material so that the operations may proceed without interruptions. The plant shall beprovided with suitable housing for protection against rain and direct sunshine.

Flexible grouting tubes, both for chemical and for cement grouting, will berequired for contact grouting, and shall be installed as required by Gener. Acceptable brandsare FUKO 2 for cement grouting and Multiject (ULTRA) or FUKO 1 for chemical grouting, orequivalents. All feeder tubes, couplings and valves shall be certified for working pressure up to120 bar.

1.7 Logging of drill holes

All drill holes shall be logged. The log shall include the following as aminimum.

Precise location, direction and length of each hole.

Location of weakness zones, including notes on variation in penetration rateand colour of returned flushing water. Location shall be recorded if loss offlushing water occurs.

Location, nature and quantity of any occurrence seepage.

Results from pressure testing shall be presented graphically.

For core drilling, the log shall in addition include information as specified inChapter 4.

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600-TU-ETG-0018

1.8 Water Pressure Testing

Water pressure testing shall be performed to determine hydraulic conductivity ofsurrounding rock mass and the need for grouting. Water pressure testing shall be carried out inboreholes as directed by Gener, and with pressures as specified.

Prior to testing, the boreholes shall be flushed with water if necessary incombination with air, for cleaning of the hole, and the equipment shall be calibrated according tospecifications listed in Chapter 4 Investigation and Instrumentation during construction.Groundwater level shall be measured prior to testing.

Water pressure tests shall be recorded in Lugeon units, and 1 Lugeon is definedas a loss of water of 1 litre per minute per metre of borehole under test at an overpressure of 10bar. If the length of the borehole under test exceeds 5 m, the length of the borehole shall betaken as 5 m for the purpose of calculating the Lugeon value. For applied overpressures otherthan 10 bar the Lugeon value shall be assumed to be linearly proportional to the test pressure.

The water pressure tests shall be performed with double packers and/or singlepackers as directed by Gener. Packers shall be pressurised mechanically or hydraulically withliquids, not inflated pneumatically. The water pressure test shall normally start with the upperpacker located at the top of the hole, and then with setting of packers at 5 m depth intervals.For each test, the water pressure shall be maintained in periods of 5 minutes with recording ofwater loss until 2 consecutive measurements of the loss are equal.

In cases where the tests indicate open or partly open connecting channelsbetween two or more boreholes, flushing with water or a combination of water and air may berequired to clean out infill material prior to grouting. For such flushing the Contractor shall haveavailable a high capacity water pump.

1.9 Grouting

1.9.1 Grouting Materials

1.9.1.1 Water

Water quality shall be as specified for concrete.

1.9.1.2 Cement

The cements to be used shall be fresh Portland Cements. Transport, handlingand storage shall conform to the requirements in the corresponding clauses of the specificationsfor cement to be used in concrete or as recommended by the manufacturer.

The cement grout shall be of the stable mix type.

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600-TU-ETG-0019

The following cement grout types may be used:

Grout type A:

Portland Cement conforming to ASTM C150 and having a specific surface of notless then 400 m2/kg (Blaine Value) with not more than 1% by weight beingretained on a sieve 200 and with stabilising and plasticising admixtures of microsilica (Elkem Materials-MultiGrout GroutAid or equivalent) and superplasticisers(Sika-SP 40 or equivalent). The maximum bleeding value shall conform to therecommendations of ISRM Commission on Rock Grouting, which state that thegrout suspension (with all additives) is considered stable when the sedimentationrate ΔH/H after 2 hours remains under 5%.

Water cement ratio: Typically 0.45 - 1.2. Marsh funnel viscosity: 36-50 sec.

Grout type B:

The cement to be used shall be micro fine Portland cements with a specificsurface of not less than 650 m 2/kg (Blaine Value), with not more than 1% byweight being retained on sieve 30. The maximum bleeding value shall conform tothe recommendations of ISRM Commission on Rock Grouting, which state thatthe grout suspension (with all additives) is considered stable when thesedimentation rate ΔH/H after 2 hours remains below 5%.

Water cement ratio: Typical 0.45 - 1.2. Marsh funnel viscosity: 36 - 50 sec.

Grout type C:

A quick setting, fine grained grout with a pot life that can be regulated in acontrolled manner between 10 minutes and 1 hour for a mix in proportion 1:1,water/cement (weight) at 25o C. Type: Accelerator aided mix designs orpremixed blocker agents as Thermax + C-Max (Elkem Materials-MultiGrout) orequivalent.

1.9.1.3 Admixtures

Gener may require the addition of materials other than those specified above in

order to improve the properties of cement grouts with respect to stability, pumpability,acceleration and retarding, and penetration ability. Such admixtures shall include, but are notlimited to, micro-silica powder, as well as expanding, water reducing, accelerating and stabilisingadmixtures.

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600-TU-ETG-00111

The Contractor shall be able to hook up to such holes for simultaneous groutingof up to 5 holes.

The grouting sequence shall start with the leanest grout mix at each packersetting. If the grout take exceeds a certain quantity of cement (will be specified duringconstruction) without increasing grout pressure, a richer grout mix or other grout types shallfollow. Grouting of one stage shall not be approved as completed until it has been set under thespecified pressure for at least 5 minutes or the stop criterion defined by Gener as maximumgrout take per meter drill hole is reached.

Grout type C shall be used for the termination of all holes if not otherwise orderedby Gener.

If grout is found to by-pass to rock surface during grouting, such leaks shall beplugged or caulked. Plugging materials and spill of grout shall be removed as required byGener.

The Contractor shall in his Tender specify the manufacturer and type of grout heintends to use.

1.9.3 Cement Grouting underground

Grouting shall be done according to procedures and criteria approved by Gener.

The procedure for cement grouting starts with drilling of grout holes. Beforegrouting, the hole shall be flushed for 3 minutes or until return water is clean. If the flushingreveals washing out of material into neighbouring holes, a more comprehensive flushing has tobe done.

All holes drilled shall be grouted. No water pressure tests shall be carried out.

Control holes will be drilled between grouted holes when the grout agents haveset, and the leakage from these holes will govern further grouting and control procedure, unlessotherwise ordered by Gener.

Packer intervals will be as directed by Gener.

Normally, cement grouting underground is to be performed at high pressure witha cement suspension consisting of cement, water and admixtures as specified. The detailedprocedure will be defined during the construction phase according to the local rock massconditions.

If grout is pressed from one hole into neighbouring holes, all holes shall begrouted simultaneously according to the procedure described above.

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The Contractor shall be able to hook up to such holes for simultaneous groutingof up to 5 holes.

The grouting sequence shall start with the leanest grout mix at each packersetting. If the grout take exceeds a certain quantity of cement (will be specified duringconstruction) without increasing grout pressure, a richer grout mix or other grout types shallfollow.

Grouting is terminated when a predefined pressure level or grout take level hasbeen reached. Grout type C shall be used for the termination of all holes if not otherwiseordered by Gener.

If grout is found to by-pass to rock surface during grouting, such leaks shall beplugged or caulked. Plugging materials and spill of grout shall be removed as required byGener.

The grout material shall be adequately set (cured) prior to blasting into a groutedarea. The required setting-time prior to commencement of drilling and blasting at the facedepends on the result of the grouting. It is a requirement that the setting-time shall be adjustedto the time needed for preparation for the next blast. Maximum normal setting time is 1 hour.Gener shall immediately be notified if longer setting-time is required.

The Contractor shall in his Tender specify the manufacturer and type of grout heintends to use.

1.9.4 Chemical Grouts

In principle, the procedures are similar as for cement grouting.

Chemical grout may be required in contacts between concrete/rock,steel/concrete, steel/rock and in rock where especially low permeability is required.

The Contractor shall in his Tender specify the type of grout he intends to use forGrout Type D and E.

1.9.5 Filling of Cavities with Concrete or Mortar (Consolidation grouting)

In cases where the exploratory drilling or testing locates open channels or cavitiesbetween concrete and rock, it may be required to fill or plug such cavities by pumping inconcrete or mortars through one or more boreholes or preinstalled tubes.

Infilling of sand, gravel or crushed rock prior to grouting or concreting may also berequired in order to achieve blocking of potential leakage channels.

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The Contractor is required to have equipment available at site for performance ofsuch works.

2. ROCK EXCAVATION

2.1 Scope and definitions

2.1.1 Coverage

This Chapter specifies requirements for all underground and aboveground rockexcavation works. Any excavation method that would fulfil the specified requirements may beused, i.e. drill and blast method and other mechanical excavation methods.

The Contractor shall provide all material, labour and equipment and carry out allworks, temporary works and tests required for completion of excavation.

The Contractor shall assume full and sole responsibility for safe workingconditions in all excavations, and the health and safety of all workers and visitors to theworksite. See also definition in Chapter 3 Rock Support. In addition to any special provisionsfor safety included in these specifications, all of Contractor’s operations shall conform to allapplicable laws and regulations.

2.1.2 Classification and Definition

2.1.2.1 General

Rock is defined as all materials, which require blasting, or the use of TBM orRBM, or the use of mechanical breakers for their removal, and which cannot be extracted by athirty tons excavator with backhoe with teeth, or equivalent equipment.

Boulders larger than 1 m3 shall be classified as rock. Boulders less than thisshall be classified as soil.

All types of materials found in rock formations underground shall be classifiedaccording to the rock mass quality classification listed below.

Gener shall decide if the material shall be classified and measured as rocks, andhis decision shall be final.

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2.1.2.2 Rock Mass Quality Classification

During excavation of rock, a rock mass quality classification will be performed byGener after each blast. To facilitate the work the rock mass quality will be grouped into fiveclasses, as defined.

q1 “Very Good”

Massive to low joint frequency, Jv < 5/m 3. Tight joints, unaltered strong rock andinsignificant stress slabbing.

q2 “Good”

Low to moderate joint frequency, 5< Jv < 10. Strong rock with none orinsignificant alteration and with coating on some joints. Low to moderate stressslabbing.

q3 “Fair”

Moderate to high joint frequency, 10< Jv < 20. Moderately strong to strong rockgenerally with coated joints and with some seams and some minor weaknesszones. The rock mass may be slightly weathered. Also applies to q1 and q2class with moderate to high intensity stress slabbing; and to medium to lowstrength rock subjected to low to medium stresses causing plastic deformations.

q4 “Poor”

High joint frequency, Jv > 20, clay seams (fault zones, swelling clays) inmoderately strong rock. Also applies to moderately weathered strong rock and tohigh to very high intensity stress slabbing in q1 and q2 class rock mass; and tomedium to low strength rock subjected to medium to high stresses causing plasticdeformation.

q5 “Extremely Poor ”

Completely crushed rock containing a significant amount of secondary clayminerals as in major fault zones. Smectite clays may lead to significant swellingand squeezing. Also applies to highly weathered rock and to low strength rockmass subjected to high stresses causing plastic deformation.

2.2 Submittals by the Contractor

2.2.1 General

Submittals that the Contractor is required to make to Gener are described below.

The issue time defines the date that Gener shall receive the first issue of thedocuments:

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XF = X number of weeks prior to start of manufacture/work as applicable.

XT = X number of weeks after completion of test/inspection/work as applicable.

2.2.2 Documents for submittal-Rock excavation

The Contractor shall prepare and submit documents in accordance with Table2-1.

Table 2-1: Documents for submittal – Rock excavation

Documentation Issue forapprovalIssue for

info. Issue time

Organisation plan for the rock excavation work showingthe responsibilities and the qualifications of the personnel. * 6F

Data sheets for explosives and detonators. * 6F

Drawings showing need and location of constructionniches. * 6F

Method of ventilation, control and monitoring systemincluding data sheet for equipment and calculation ofventilation and energy requirements.

* 6F

Excavation procedure for each area, including intendedrock excavation, removal and deposit method, timeschedule and sequence for excavation, rock support andmonitoring.

* 6F

Description of blasting procedure, including position anddepth of holes, types of explosives, size of charges, timing

and firing sequences.

* 6F

Procedures for geometric control. * 6F

Weekly progress report for excavation, showing plannedprogress versus actual progress (cut off Sunday at 2400hours).

* 1T

Monthly documentation of correct setting out of theexcavation contours (cut off last Sunday each month at2400 hours).

* 1T

Gener ’s approval does not relieve the Contractor of his sole responsibilities forefficient and successful execution of the work.

2.2.3 Test Reports

The Contractor shall perform tests and prepare and submit test reports inaccordance with Table 2-2.

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Table 2-2: Documents for submittal – Blasting tests

Item Issue forapprovalIssue for

info Issue time

Perimeter blasting test report * 1T

Blast vibration test report * 1T

2.2.4 Documents for submittal-TBM excavation

The Contractor shall prepare and submit documents in accordance with Table2-3.

Table 2-3: Documents for submittal – TBM excavationItem Issue for

approvalIssue for

infoIssue time

TBM specifications, cutter head and back up system,complete * 6F

List of major spareparts, at site, workshop andmanufacturer * 6F

Description and data sheets for mucking system * 6F

Description and data sheets for secondary transportsystem in tunnel (personnel, equipment and materials) * 6F

Working procedure for each area, including intendedrock excavation, time schedule and sequence forexcavation, rock support and monitoring

* 6F

Description and data sheets for exploratory and groutingdrilling ahead of face * 6F

Description and data sheets for grouting equipment andmethod * 6F

Description and data sheets for rock drills and bolting atcutter head and behind * 6F

Description and data sheets for application of sprayedconcrete between cutter head and back up. * 6F

Description and data sheet for installation of circularsteel sets and wire mesh at cutter head, including theerector

* 6F

Procedures for material and equipment supply to tunnelfront, including for excavation, rock support and groutingworks

* 6F

Organisation plan for the TBM rock excavation workshowing the responsibilities and the qualifications of thepersonnel

* 6F

Description and data sheets for Monitoring and Loggingsystem for TBM operational data * 6F

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Reporting procedures * 6F

Routine reports * 1T

Gener ’s approval does not relieve the Contractor of his sole responsibilities for

efficient and successful execution of the work.

2.3 Rock Excavation

2.3.1 General Requirements

Prior to commencement of the work, the Contractor shall submit to Gener a planshowing manpower and equipment for excavation and support work intended to be used, spareparts and supplies on the Site, and the expected advance rate of excavation and tunnellingincluding time for support work. Only experienced supervisors, foremen and well-trained

tunnelling crews shall be employed for the work.

The Contractor shall be responsible for the management and sorting of allexcavated materials to enable the placement and disposal of materials in accordance with theContract. Excavated materials shall, according to their nature and to the Contractor's materialsmanagement plan, be placed as fills in their final locations in the Works, stockpiled for laterplacement, used for aggregate production, or removed to a nominated or approved spoildisposal area. All excavated materials belong to Gener and no material shall be removed fromthe Site without the written approval of Gener.

Excavation in rock shall achieve stable, reasonably regular rock slopes andsurfaces with as little overbreak as possible. Excavation of the underground caverns shall bedone in stages. The bench height above- and under-ground shall not exceed heights giving fullaccess for rock-strengthening works in the walls of each bench.

The Contractor may choose his own methods for drilling, blasting andtransporting the rock. Except where otherwise specified, perimeter blasting shall form the finalsurfaces in underground openings. Charging of drill holes as well as type of ignition, drillingpatterns etc., shall be according to modern methods and recognised good practice.

The Contractor shall observe and carry out all excavation work according to rulesand regulations regarding the import, transport, storage and use of explosives issued by andpublic authority having jurisdiction in respect of the same. Detailed records shall be kept by theContractor and submitted daily to Gener giving the types and quantities of explosives used,delivered and in stock. Transport of explosives and detonators shall be in vehicles suitablyequipped for this purpose.

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The Contractor shall not later than 6 weeks ahead of start of blasting works,provide Gener with a list of blasting licence holders. Only qualified persons shall be permitted toconduct blasting operations.

Where firing is carried out electrically the Contractor shall take all precautionsnecessary to prevent premature explosions. During thunderstorms and other electricaldisturbances charging and firing is not permitted and warning shall be given to all operatorswhen charging is in progress.

An instrument measuring static electricity levels shall be installed at each tunnelportal. The instrument shall be connected to an easily visible warning device.

All metal mains, ducts and tracts shall be properly earthed at the entrance to theunderground working.

Gener may require use of non- electric ignition systems without additionalcompensation to the Contractor.

The times at which blasting may be carried out are to be subject to the approvalof Gener and shall be decided so that the blasting does not unreasonably disturb the populationor other works.

After excavation of soil material, the rock surface shall be sufficiently cleaned fordrilling and placing of explosives to the satisfaction of Gener. The cleaning shall be done to atleast 1.5 m outside theoretical rock contour lines or 1.0 m outside actual contour lines.

The design theoretical rock contour lines and levels of excavations are defined asthose shown on the Drawings or specified in the Contract, or as adjusted at site or otherwisedetermined by Gener.

Excavations shall follow the theoretical rock contour lines and levels or such otherlimits as the Contractor may require to enable him to construct the Works in accordance with theContract considering collaring accuracy and hole deviation specified. Excavation beyond thetheoretical rock contour lines and levels made without Gener's direction or approval, includingbut not limited to, excavation to provide working space and excavation below approved strippinglevels, shall be backfilled with concrete at the Contractors expense unless otherwise specified orapproved.

The Contractor shall be solely responsible for all damage or accidents resultingfrom blasting of temporary, permanent or subsidiary works, or to the property of Gener or ofothers, as well as for injury to persons.

The Contractor is responsible for covering and required protection in connectionwith blasting. Debris from blasting and spill from transportation are not allowed outside the

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excavation area. The Contractor has to clean up such material as Gener finds it necessary.The Contractor shall regularly inspect the excavated fronts of all works under his jurisdiction,including temporary and permanent access roads and shall forthwith remove and dispose of anymaterial, which Gener and/or the Contractor deem loose or unsafe.

Blasting in the vicinity of completed, or partially completed, concrete structuresshall be subject to Gener ’s consent. Normally, blasting shall not take place in the vicinity ofnewly concreted structures until 10 days after concreting. The restriction does not apply toblasting close to installed rock support in underground openings.

Limits for blasting induced vibrations from repeated events are defined as peakparticle velocities (mm/sec) measured at the structure. The limit is valid for both horizontal andvertical peak particle velocities and is given in Table 2-4. For single events Gener will establishless stringent limits in each case.

Table 2-4: Limits for peak particle velocityType of construction Peak particle velocity

Ordinary buildings founded on soil 20 mm/sec

Ordinary buildings founded on rock 50 mm/sec

Massive concrete structures founded on rock 70 mm/sec

Adjacent permanent underground openings 100 mm/sec, or as determined byGenerTanks, pipes and valves. Measured on foundation to rock 40 mm/sec

Tanks, pipes and valves. Measured on foundation on soil 20 mm/secTransformers and other sensitive equipment in operation.Measured on foundation. 12 mm/secTransformers and other sensitive equipment not inoperation. Measured on foundation. 40 mm/sec

Gener may adjust limits according to characteristic frequencies obtained andexperience gained during execution.

The Contractor shall monitor blasting operations as well as magnitude andintensity of ground vibrations when required. The Contractor is responsible for keeping the peakparticle velocity below given limits and to document this by vibration recording instrumentsavailable at the site. The vibration recorder shall have minimum 3 channels and be able torecord peak particle velocities in the range 1 - 250 mm/sec with an accuracy of 1 mm/sec. Theinstruments shall give linear recordings in the frequency area 5 to 300 Hz. Geophones forhorizontal and vertical PPV measurements shall be available. The records shall be submittedweekly. The Contractor shall provide a yearly certificate from the manufacturer or approvedauthority verifying the accuracy of the vibration monitoring apparatus.

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Before commencing the rock excavation work, the Contractor shall work out andpresent a quality assurance plan that ensures that the rock excavation work is performedaccording to the Contract requirements.

The rock surface shall be inspected after each blast, and action for immediatesecuring at the face shall be taken as required. Gener shall have access to the face in order tocarry out mapping of the rock conditions revealed. In cases of adverse rock conditions orsignificant deterioration of the conditions Gener shall be notified immediately.

2.3.2 Ventilation

The ventilation system shall be efficient and reliable during the excavation periodin order to provide a safe and comfortable working environment inside tunnels and caverns.

Toxic gases shall not exceed levels according to local requirements or as shown

in Table 2-5 whichever is strictest, at any time when people are in the tunnels:

Table 2-5: Limits for toxic gas levels

CO 35 ppm

CO 2 5000 ppm

SO 2 2 ppm

NO 2 2 ppm

NO 25 ppm

Air velocity shall always be higher than 0.3 m/s in the cross sectional area oftunnels and caverns. The air breathed by persons shall contain not less than 19% of oxygen byvolume.

The environment inside the tunnel will be governed by seasonal variations intemperature, humidity, rock temperature and by work activities ongoing within the tunnel.

The maximum wet bulb temperature inside the tunnel shall not exceed +28ºC.

The fans shall be robust and efficient. Each fan shall be capable of providingvariable airflow to suit the construction sequence and activity level inside each tunnel as workprogresses. Each fan shall be supplied complete with all necessary components forcommissioning and use.

Noise emission of each fan shall not exceed 75 dB (A) measured at 45º to theaxis of the fan at a distance for 10 m from the inlet.

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All components of the duct system shall be non-flammable.

The ducting shall be of a safe robust material. Flexible ducting shall have a hightear resistance and shall be appropriately reinforced and maintained.

The ducting system shall be resistant to the tunnel environment and shall notdeteriorate as a result of inter alia:

Condensation

Diesel and nitrous gases

UV light

Weak dilutions of acid

If the Contractor expects the conventional ventilation system to be insufficient forkeeping the wet bulb temperature below 28ºC, a separate cooling system shall be installed. Thecondenser shall be water-cooled.

A control and monitoring system for optimisation shall be provided.

The Contractor shall describe the details of the system that will be used.

The parties to the contract shall produce a schedule of gases and pollutants to betested for, including both the frequency and the methods of testing. The recommendations of

BS 6164 Section 4 shall be followed, but this shall not restrict the range of testing to be carriedout in any particular location.

2.3.3 Illumination, Communication and Roadways

The Contractor shall install and maintain illumination as required for safe andefficient working conditions and inspection of the work executed.

The Contractor shall install and maintain a system of telecommunication at allwork fronts.

The Contractor shall maintain all temporary and permanent roadways in good anddry conditions to facilitate efficient and quick transportation aboveground as well asunder-ground.

2.3.4 Survey

All surveying shall be carried out as specified for Surveying work.

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2.4 Open Cut Excavation

Excavation beyond the theoretical rock contour shall wherever possible bebackfilled with approved concrete, unless otherwise directed by Gener.

The slopes of permanent batters are assumed to be vertical unless other slopesare given on the Drawings or directed by Gener.

During the progress of the work Gener may examine and investigate the groundrevealed in the excavations and may carry out investigations of groundwater levels, soil androck properties in the ground adjacent to the excavations. Such investigations may requirealterations to the limits of the excavations for such purposes as to provide sound foundations orstable batters.

In the Bill of Quantities rock excavation is divided into the following categories:

Bulk rock excavation andTrench/ditch rock excavation with bottom width less than 2.0 m.

2.5 Underground Excavation

Underground excavation comprises excavation of all tunnels, shafts, caverns andother underground openings shown on Drawings. Any recesses, trenches, enlargements etc.required by the Contractor will not be measured for payment.

The excavation procedure shall always be adapted to the local rock massconditions. When traversing weakness zones or other areas of heavily jointed or otherwiseincompetent rock, pilot tunnelling, dividing of the section, and/or advancing with shorter pull thannormal may become necessary. Spiling, immediate application of sprayed concrete, reinforcedsprayed concrete lining, pressure grouting or other support measures, further described inChapter 1 and Chapter 3, may also be required. The methods to be used for excavation andsupport shall be subject to Gener's approval.

In all waterways a rigid template of the same shape and dimensions as thetheoretical cross-section shall pass through. The direction along which the template movesshall nowhere be more than 7° off the theoretical alignment.

Any subsequent slashing, wedging or re-drilling of rock that may be necessary inorder to meet the above requirements is the responsibility and cost of the Contractor.

Control of compliance with the design requirements shall be carried out by theContractor at regular intervals as directed by Gener.

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2.6 Drilling and Blasting (Above- and Underground)

2.6.1 General

Prior to excavating rock at a given location the Contractor shall, after notifyingGener, carry out a survey of the surface of the rock as agreed by Gener (See also specifications

for Surveying work).

Before commencing any drilling and blasting the Contractor shall submit forGener's approval the drilling-, charging- and ignition patterns he proposes to use. Suchapproval shall, however, not exempt the Contractor of the full liability of any blasting operations.

The drilling equipment shall include a device for measuring the direction ofdrilling.

In order to minimise overbreak and requirements for rock support, perimeter

blasting (soft blasting smooth contour blasting technique) shall be used on all final rocksurfaces.

The length and size of blast rounds shall be regulated according to the prevailingrock conditions. When deemed necessary from stability considerations, Gener can orderreduced round lengths and/or subdivision of the cross section.

When deemed necessary from stability considerations, Gener can order changein excavation shape, both the arch height and the symmetry, within the given cross-sectional area.

Design drawings show the theoretical rock contour. Special rock mass conditionscould require cross-section adjustments which shall be decided and/or approved by Gener.

2.6.2 Excavation Tolerances

The excavated area shall at no point be less than the theoretical area for eachsection given on the Drawings. Rock protrusions inside theoretical contour lines are notaccepted.

If the Contractor considers it necessary to request for excavation outsidetheoretical contour to obtain access for temporary works or installations, such request shall beforwarded to Gener and the work shall be at the Contractor cost and time.

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2.6.3 Drilling Accuracy

The general requirements for drilling accuracy are as shown in Table 2-6.

Table 2-6: Drilling accuracy

Excavation Drill holes/row Collaring Alignment Aboveground Contour holes 100 mm 2% of depth of hole

Aboveground Next rows 200 mm 2% of depth of hole

Underground Contour holes 100 mm 4% of depth of hole

Underground Next rows 200 mm 6% of depth of hole

Shafts Pilot holes and reamed shaft 100mm 1.5% of depth of shaft

TBM tunnels/shafts Tunnel centerline NA +/- 50mm in all directions

2.6.4 Perimeter Blasting

2.6.4.1 General

Perimeter blasting shall be applied on contours in order to ensure smooth finalsurfaces, minimise overbreak and reduce the subsequent support measures. Smooth blastingor pre-splitting may be applied.

This includes drilling of contour holes c/c 700 mm with max. diameter Ø51 mmand use of special low strength explosives. The row next to contour holes may also requirecharge limitations.

As a general rule the distance between the perimeter and the nearest row ofholes of the main round shall be 1.3 times the spacing of perimeter holes for smooth blasting.For pre-splitting this distance shall be 0.5 times the burden in the main round, or smaller thanthe average joint spacing.

The selection of these and other pertinent parameters shall be based onexperience gained from the initial rounds, and shall be subject to the approval of Gener.

2.6.4.2 Smooth Blasting

The result of smooth blasting is governed by the following parameters:diameter of contour holes,

spacing of contour holes,

distance between the row of contour holes and next row of holes (burden),

type and size of charges used,

ignition pattern.

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This method is based on closely spaced contour holes, with reduced charges tobe fired as a final clean-blast after the main round on the last number of delays. The methodshall prevent extensive fracturing of the rock mass beyond the contour.

2.6.4.3 Pre-splitting

The principle of pre-splitting differs from that of smooth blasting mainly by itsignition pattern. The contour holes are blasted prior to the main round, and the crack formedshould act as a barrier which will tend to limit further fracturing of the rock mass beyond thecontour from the vibrations of the main round.

2.7 Drilling and Reaming of Shafts by raise-boring machine (RBM)

The Contractor selects the type of the raise-boring equipment he intends to apply.

The proposed working methods for the various tunnel sections and shafts shall bedescribed in detail by the Contractor and submitted with the Tender. The Contractor shallsubmit a description with his Tender of details on the RBM and of the ancillary equipment to beprovided, with particular emphasis of the items listed below.

A high degree of drilling accuracy is required and defined according to Table 2-6.

Registration of rock mass quality shall be performed concurrent with drilling of thepilot holes. Any abnormalities shall be reported immediately to Gener and the requirement forstabilisation grouting by high pressure shall be evaluated concurrent with the drilling.

Pilot holes shall be grouted and re-drilled if required.

Where shaft excavation or raise boring operations intersect proposed orcompleted tunnel alignments, the Contractor shall prepare a detailed work plan (includingtemporary works as necessary) to indicate and assure the proper coordination and avoidance ofinterferences between tunnelling and shaft construction. This is also required for rock supportworks to be performed in the shafts.

2.8 Tunnel excavation by tunnel boring machine (TBM)

2.8.1 General

For the sake of clarity, the following terms shall be used in connection with theWork as defined herein:

a) Excavation by TBM: Continuous excavation of tunnels by means of afull-face boring machine (TBM).

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b) Excavation by raise boring: Continuous excavation of shafts by means of araise-boring machine (RBM).

c) Excavation by drilling and blasting: Excavation of tunnels and shaftsapplying drilling and blasting (D&B).

d) Heading face: The advance end of a tunnel or other excavation at which thework is progressing.

e) Machine zone: Refers to tunnels excavated by a TBM and is defined as thespace between the heading face and the outer end of the rear grippermechanism + 10 m rearwards.

f) Backup equipment zone: Refers to tunnels excavated by TBM and isdefined as the space between the end of the machine zone and the end ofthe TBM auxiliary equipment.

g) Rear zone: Refers to the entire tunnel or shaft section extendingrespectively from the heading zone, or bottom range zone, or for TBMexcavation the backup equipment zone, to the portal.

h) Stroke: The advance of the heading face in a TBM excavation from one re-grip to the next grip.

General technical requirements and specifications related to tunnel excavationare presented in Chapter 2 above and are valid also for TBM excavation.

The Contractor selects the type of TBM to be used, as specified in 2.8.2 below.The proposed working methods and equipment for the various tunnel sections shall be

described in detail by the Contractor and submitted with the Tender, including description also ofthe ancillary equipment to be provided, with particular emphasis of the items discussed below.

The TBM's shall be new, or refurbished for use on this Project, and shall beassembled on completion of fabrication or refurbishment, before shipment, and tested todemonstrate that all components operate correctly. Gener shall be permitted to witness testingand to inspect TBM's at the premises of the manufacturer or refurbishing contractor at any stageduring fabrication or refurbishing. Such inspections or testing shall not release the Contractorfrom any obligation as specified under the Contract.

The specified diameters are the minimum bore diameter to be allowed, aftermaximum allowed wear of the edge cutters is reached.

2.8.2 Requirements to TBM machines

The Contractor selects the type of TBM machines to be used. The machinesmust be capable of coping with the expected rock conditions, in particular with the expectedhard rock, mixed-face conditions and varying rock cover in a satisfactory manner and shall be

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equipped accordingly. The capability of the TBM machines includes but are not limited to thefollowing technical requirements:

The TBM's must be built for and equipped with back loading cutter system havinga minimum cutter diameter of 482,6 mm (19”) .

Minimum cutterhead power (torque) shall be 2200 kW for the Alfalfal II andVolcan machine options, 3000kW for the optional Las Lajas machine.

The TBM machines shall be equipped with variable frequency drive system.

The TBM cutterhead shall be designed and constructed for allowing overcuttingwhen required, minimum 100mm around the tunnel periphery.

The bidder shall include in his offer one spare main bearing for each TBMmachine in stock at manufacturer workshop or at his own stock facilities.

An adequate stock of spare parts shall be maintained at the Project Area,ensuring that interruptions for maintenance and repair will be kept to a minimum. A list of majorspare parts that will be available at the Project Area shall be submitted with the Tender.

The TBM machines shall be equipped with a monitoring and logging system forTBM operation data. Machine operating parameter data shall be collected in real time, storedand moved from the TBM to the surface by either manual methods or by a cabled modemsystem. File structure shall be exportable to the user applications MS Excel and MS Access.

In addition to this, a simplified method for monitoring and logging of the operationof the TBM shall be established by installing an Ampere reader and logger at the transformerunit supplying the TBM. The reader and logger shall be connected to the site office of Gener, inorder to make him able to follow tunnel activities on a continuous basis.

Access to the heading face, also for Gener must be assured.

Should the excavation progress show that the selected TBM is inadequate orunsuitable to complete the drive under the terms of the Contract, then the Contractor will beobliged to proceed with D&B excavation under the same contractual obligations as with TBMexcavation. In such case the Contractor will have no right whatsoever to claim for any extensionof the time for completion of the Work.

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2.8.3 Backup system

Backup system must be designed and constructed to permit the excavation of theactual tunnel geometries, including capability to pass through areas where the 100mmovercutting is performed by the cutterhead, or where reduced due to heavy rock support.

Solid protection roofs have to be installed over all workplaces, i.e. locations whereworkers are stationed on a more or less continuous basis.

The Contractor shall detail and explain with his Tender the mucking system, ofsufficient capacity, he intends to use and, as applicable, the type of transport system he intendsto use including provisions for tunnel dewatering along the invert.

The accuracy of the advance shall be continuously assured by a laser beam anda guidance monitoring and logging system with high accuracy in order to comply with the stricttolerances for the tunnel alignment defined in Table 2-6.

2.8.4 Exploratory drilling, grouting and rock support

Technical requirements and specifications related to exploratory drilling, groutingand rock support defined in Chapter 1 Drilling of holes, exploratory drilling and grouting andChapter 3 Rock support are valid for tunnel excavation with TBM, unless otherwise stated in thisChapter 2.8.

TBM's have to be constructed so that proper and efficient installation of all rocksupport elements (rockbolts, spiling bolts, sprayed concrete, circular steel sets, lattice girders,wire mesh etc.) is possible both in the machine zone and in the backup equipment zone.

Depending on rock conditions, it will at times be necessary to place initial supportnear the heading face, in front of the grippers. In this area it shall be accommodated forminimum two drilling machines for drilling and installation of radial rock bolts, one machine oneach side of the main beam of theTBM. These drills shall be mounted on custom designedfixtures which allows them to be used while the TBM is advancing, and to bore a near-radialpattern of holes in the rock for the installation of dowels and rock bolts. Each drill shall havecapacity and technical specifications complying with Atlas Copco 1238 or equivalent equipmentand be operated completely independently of the other drill.

A circular steel set erector system shall be installed immediately behind thecutterhead, and capacity shall be available to enable installation of steel sets in this areawhenever required. The steel set erector shall also allow for efficient installation of latticegirders and wire mesh in the same area of the TBM.

The grippers of the TBM shall be equipped with recesses in order not to deformthe steel sets and lattice girders when passing by them.

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Each TBM machine shall be equipped with minimum 2 drilling machines allowingfor drilling holes ahead of tunnel face for exploratory and grouting purposes, in addition to drillingfor spiling bolts, as specified in Chapter1 Exploratory Drilling and Grouting, and in Chapter 3Rock support.

These probe drills shall allow for drilling of holes around nearly the entire 360degree perimeter at a variable lookout angle of 10-30 degrees from the centre line of the tunnel,and shall be subject to the approval of Gener.

Hole lengths shall be up to 50 meters for exploratory and grouting holes. Thesedrillholes can only be performed when TBM boring operation is stopped, and therefore thedrilling capacity must be the best possible, complying with capacities and specifications aspresented by Atlas Copco 1838 or equivalent. These drilling machines should also be capableof drilling spiling bolts ahead and around the cutterhead, in umbrella pattern, and with lengths upto 8 meters, also at a variable lookout angle of 10-30 degrees from the centre line of the tunnel.

Two complete grouting lines shall be installed and operated along the back upsystem.

High capacity Robots for sprayed concrete application during boring process shallbe located in the machine zone. Collector buckets for rebound material shall be allowed for.Double lances running on rings or equivalent high capacity equipment shall be provided, beingsupplied by twin sprayed concrete pumps, installed along the back up and at considerabledistance away.

2.8.5 Invert concrete segments

Invert concrete segments shall be supplied and installed in the machine zoneduring excavation of all TBM tunnels. The segment design and installation shall allow for properand efficient placing of steel sets and lattice girders in the same area. The tunnel invert shall beproperly cleaned before placing the invert segments. These segments shall be embedded incement mortar to allow for levelling.

2.8.6 Assignment of risk during TBM excavation

The risks assigned to the Contractor include, but are not limited to the following:

All risks related to mixed-face conditions; the Contractor is expressly madeaware of the extensive mixed-face conditions expected along the tunnel andshall provide a suitable TBM of robust construction and of proven design forthe anticipated conditions.

Additionally the importance of cutter size selection and of the cutter design isemphasised for which all risks are expressly assigned to the Contractor.

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All mechanical defects and break-downs of the TBM machinery andequipment.

All occurring variations in rock mass quality and in rock properties, bothintact rock properties and rock mass properties.

All frequent changes of rock properties and rock mass quality.

Obstruction or interruptions of the loading and transporting operations due toclogging of the excavated material or the occurrence of large single bouldersor pieces of rock.

Inflow of water and all hindrance to the advance due to water.

The risks assigned to the Owner are the following:

Those risks compensated by the unit prices in the Bill of Quantities and the

regulation of construction time according to Chapter 6 below

The quantities allocated to exploratory drilling, grouting and rock support

2.9 Utilisation of Materials

Excavated materials shall be used for forming of fills or spoiled as approved byGener. Unless designated by Drawings or by Gener spoil areas shall be proposed by theContractor and approved by Gener. Treatment and works at fill and/or spoil areas are coveredunder Specifications for Earthworks.

3. ROCK SUPPORT

3.1 Scope

3.1.1 Coverage

This Chapter comprises all work intended to support and stabilise the rockwhether of initial or permanent nature, in open cuts or in underground openings.

The Contractor shall provide all material, labour and equipment and carry out allworks, temporary works and tests required for completion of the work.

The Contractor shall assume full and sole responsibility for safe workingconditions for all excavations and the health and safety of all workers and visitors to the workduring the construction period. In addition to provisions for safety included in these

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specifications and elsewhere in the Contract, all of Contractor’s operations shall conform to allapplicable laws and regulations.

3.1.2 Classification and Definition

3.1.2.1 General

Support work shall be carried out in accordance with the following definitions:

“Initial rock support” shall mean support work necessary to ensure safe workingconditions and to maintain the shape of the rock excavation during theconstruction period.

“Additional rock support” shall mean all support work necessary to ensure thepermanent long-term stability of the excavations.

"Support work at the face" shall mean all support work interrupting the normalexcavation cycles, except that all support work carried out in caverns (as, forinstance, the powerhouse cavern including busbar tunnels and niches fortransformers) and above ground, in open cuts etc., shall be regarded andmeasured as support work behind the face. All support work carried out ahead ofand along the TBM back-up shall be regarded and measured as support work atface. All support work carried out in RBM-shafts shall be regarded and measuredas support works behind the face.

"Support work behind the face" shall mean all support work not being measuredas carried out at the face.

The rock support consists of combinations of scaling, rock bolts, sprayedconcrete, several forms for reinforcement for the sprayed concrete including lattice girders andfull concrete lining. For TBM tunnels, also circular steel sets are required.

3.1.2.2 Rock Mass Quality Classification

During excavation a rock mass quality classification will be performed by Generafter each blast (or during TBM boring). To facilitate the work the rock mass quality will begrouped into five classes as defined in Chapter 2.1.2.2 Rock mass quality classification.

3.1.2.3 Rock Support Classification

The basic Rock Support resources (RS) used for each rock mass category (q)may in principle be listed as follows:

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q1 => RS 1: Scaling and spot bolts.

TBM/reamed shaft: Scaling and spot bolts.

q2 => RS 2: Scaling. Spot bolting for smaller cross-sections. Pattern boltingand spot applied fibre reinforced sprayed concrete for largercross-sections.

TBM/reamed shaft: Scaling and spot bolts.

q3 => RS 3: Scaling. Pattern bolting and minimum one layer of fibre reinforcedsprayed concrete in crown and walls for smaller cross-section.Number/length of bolts and thickness of sprayed concrete dependon the cross-section.

TBM/reamed shaft: Scaling, spot bolts and partial use of fibrereinforced sprayed concrete.

q4 => RS 4: Pattern bolting and a minimum of two layers of fibre reinforcedsprayed concrete in crown and walls for smaller cross-section.Occasionally (i.e. on 10 - 20% of the length) reinforced ribs ofrebars/lattice girders and sprayed concrete or concrete lining.Occasionally concreting of the invert at face could be selected.Number/length of bolts and thickness of sprayed concrete dependon the cross-section. Also applies to short blasting rounds andsubdivision of rounds depending on cross-section.

TBM and RBM: No use of concrete lining at the face (circular steelsets might be installed behind cutterhead).

q5 => RS 5: Pattern bolting and spiling bolts. Fibre reinforced sprayed concretewhen short stand up time and application of reinforced ribs ofrebars/lattice girders and sprayed concrete at the face andconcrete lining behind the face. Reinforced ribs may be omitted ifconcrete lining is cast at the face. Concreting of the invert at facecould be selected. Number/length of bolts and the thickness ofsprayed concrete as well as the distance between the latticegirders depend on the cross-section. Also applies to systematicshort rounds for small cross-sections and