Constructo de safto la tunl- Yennigum Company

35MW NAGDAR HYDROPOWER PLANT PROJECT _

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8. TUNNELS AND SHAFTS

Planning Shift Per Day : 2 Planning Hour per shift : 10

8.1 TUNNELS The Headrace, Tailrace & Access Tunnels and all underground excavation works will be carried by

NATM (New Austrian Tunneling Method) principles of drill and blast.

During tunnel excavation, the selection of the type of ground support of the tunnel will be done

according to the geological conditions and the projects.

The excavation and the ground support works will be carried out fast, safe and most economical way.

On the other hand, the priority will always be the Health and Safety principles.

In order to access to the tunnel entrance, at first galance the portal excavations and ground support

works shall be completed. In soft rock, the excavation shall be carried out with hydraulic jack

hammers. In hard rock rock conditions, the excavation of the portal shall be carried out drill and blast

method. After the excavation, the ground support works shall be carried out for portal structure. In

order to obtain smooth slope faces, pre-splitting drill & blast method shall be executed. The drilling

procedure shall be carried out by hydraulic drillers according to the drilling pattern. After drilling,

blasting shall be carried out by expert blasters.

After excavation and ground support of Portals, tunnel excavation shall be commenced immediately.

The tunnel excavation shall be carried out mainly with drill & blast method. The advance shall be


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carried out with hydraulic hammers where the tunnel geology is composed of soft rock formation.

The advance lengths of excavation shall be determined according to the tunnel geology and suitable

ground support. For the section where drill & blast method will be applied; the blasting holes shall be

drilled by drill jumbos according to the drilling patterns and blasting shall be executed by licensed

blasters in a safe way.

During the excavation works following procedure shall be executed in order;

1. Excavation

2. Drilling

3. Charging

4. Blasting

5. Ventilation

6. Mucking

7. Installation of Steel Ribs (if necessary)

8. Forpoling (if necessary)


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9. Fiber Reinforced (if Necessary) Shotcrete

10. Wire Mesh Installation (if necessary)

11. Rock Bolt Installation (if necessary)

After the excavation process, the mucking material shall be loaded rapidly and transported to the

dump areas by special underground loaders and dumpers. After the portal excavation, during the


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headrace tunnel excavation, it is planned to use special rail wagons to load the mucking material

which is pulled by locomotives in order to increase the excavation speed in a safe way.

This set up can be summarized as; a platform which assembled on a pair of rail, on this platform a

driller which is used for drilling holes, a high speed loader for mucking and loading wagons for

mucking material and locomotive for transporting these equipment inside and outside of the tunnel.

By this method, the excavation speed of the headrace tunnel will be increased which is the critical

path of the Project.

It is planned to reach an average speed of 150 -160 meters per month during excavation. In case of

conventional method of drill & blast will be executed; loading niches shall be constructed every 200

meters.

• It is planned to make the excavation 2 rounds a day. Considering a round length of 3 meters,

the monthly advance shall be 150 – 160 meters.

• Due to lack of electricity in construction site, the necessary energy shall be provided by

generators 400 & 700 kVA.

• The necessary water for drilling and grouting works shall be supplied from water tanks (20

tones capacity) which is placed to tunnel portal. Water shall be pumped through pipes inside the

tunnel.

For concrete lining works, which shall take place after excavation works completion, 2 sets of running

shutter of 9 meter length (each) is planned to use. In each set of shutter 6 pieces of collectors and 30

pieces of vibrators will take place. It is planned to reach a speed of 180 meters per month during


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lining stage. Enough amount of concrete pumps shall be ready work site. The technical specifications

of the running shutters shall be as follows;

a. The design of the shutter will be done by the manufacturer according to he specifications; ACI 347,

DIN 18218, DIN 18800

b. The adjustments of the shutter shall be done by hydraulic engines.

c. The surface plate thickness of the shutter shall be 10 mm and with a quality of EDC A1 steel.

d. The face form of the shutter shall consist of timber elements .

e. The assembly of the shutter and the first lining concrete shall be sone with supervising service of

the manufacturer. All necessary cranes and equipment shall be ready at work site.

BLASTING METHODS

The blasting materials what will be used during excavation

• Explosive : Emulsion Base Detonator Sensitive

(Powergel Magnum 365 or Emulite TG)

This explosive will be used as main charger. The consumption is depending on the rock mass quality.

• Secondary Explosive : Powergel Trimex, Gurit or Det. Cord 80gr/m

(For Smooth Blasting)

For tunnel excavation, in necessary conditions, these materials shall be used for obtaining a smooth

excavation surface.

• Detonator Cord : Detonator Cord 80gr/mt

This material will be used in surface holes in order minimize the disturbance of the rock and

preventing the overbreaks.

• Detonator : Exel or Nonel LP Detonator

For tunnel excavation, it is preferable to have as much retardants as possible. For this reason, Nonel

LP detonators will be used.

• Detonator Cord : Detonator Cord 5-6gr/mt

This cord will be used in order to ignite the LP Detonators.

• Initiator : Electrical Detonator

It will be used to initiate the blasting with burning the detonator cord. 1 or 2 pieces will be used in

each blasting.


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The representative drillings for blasting patterns for Tunnels;

Mobile blasting stores will be needed in order to supply sufficient amount of blasting materials

according to the regulations of the country.

Surge Tank Drilling Pattern with 6 meter diameter

After the pilot hole excavation with RBM, the enlargement of the Surge Tank will be done with drill

and blast method mentioned above.


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RAILBORNE DRILLING, LOADING AND TRANSPORT

IN THE NAGDAR AND DOWARIAN HEPP POWER TUNNEL

For this confined tunnel, we propose HSTM (High-Speed tunneling Method) consisting of 2 set of Rail

drill 282, Häggloader 8HR2, Shuttle train 140-CE transport system consisting of 8-cars train,

Locomotives DHD25 and D8.

HÄGGLOADERS 8HR2 AND 8HR5

The Häggloader is one of the components in the High Speed Tunneling System. It is a loader with high

production capacity that can work in confined tunnel sections together with our Shuttle train tunnel

transport cars.

The Häggloader can, besides loading, also be used for lifting rails into place, handling an Omega rail-

extension system and digging trenches in the tunnel floor.

Our Häggloader model 8HR is constructed to work in tunnels 2.0-4.0 meters in width and its larger

cousin the 8HR5 will handle tunnels from 4.5-7.2 meters width. Please note, however, that each

Häggloader has to be fitted to each tunnels specific width.


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Loading capacity of the 8HR-2 version is on average 2.5 cubic meters/min loose rock, but can be

increased to between 3.0-3.5 cubic meters/min depending on the height of the blasted muck-pile.

For the larger 8HR5 the loading capacity is 6.0-9.0 cubic meters. The mucking capacity of a

Häggloader is proportional to the digging width, (which in turn determines the length of the strokes

of the arm and gathering capacity), the height of the pile and installed capacity.

SHUTTLE TRAIN TRANSPORT CARS

The Shuttle train is designed for transport in tunnels and drifts and is composed of several car units,

linked together. A conveyor in the base of each car transfers the rock inside the train, from the

loader in the front to the last car, to fill the complete train. No car-shunting is needed.

By matching the number of cars in one train to the volume of the blasted rock, the complete round

can be removed by one train set. This is the principle of the High Speed Tunneling method,

minimizing the need for time consuming car switching and trimming throughout the tunnel. Only two

or three trips are required, first drilling and blasting, then one or two for mucking and transport.

Shuttle cars are available in different sizes, with carrying capacities of 9.0, 11.5 and14.0 cubic meters

respectively. However, in this size of the tunnel we recommend the use of

Shuttle train HRST-140CE.

8.1.1 CLEANING PRIOR TO LINING AND LOADING IN SOFT ROCK CONDITIONS

Both the 8HR2 and the 8HR5 can be fitted with a back-hoe digging system and used for

cleaning up prior to lining the floor. The back-hoe system is also useful when loading in bad

rock conditions or where there is a high water content in the muck.


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The Häggloader equipped with back-hoe digging attachment can also assist in various other

work, such as scaling the face, lifting rail sections into place, and digging drainage trenches in

the tunnel floor.

With a quick coupling system the bucket can be replaced by a hydraulic breaker, work

platform, or lifting brackets for erecting steel arches. Additionally the bucket mount can be

rotated 360º and/or tilted ± 30º.

EXCAVATION THE "NATM" METHOD

Both our small and large loaders equipped with back-hoes have been used in the NATM

(New Austrian Tunneling Method). The tunnel face is excavated in several steps like Top and

Benching or with pilot tunnels.

For example, with a quick coupling system, the bucket can be replaced with a hydraulic

breaker for hammering in steel sheet piles above the arches. Under the protection of steel

roof and shotcrete, the system can be switched back to bucket mode and the loader proceed

with its excavation.

Digging out the top and stabilizing with shotcrete

Erecting arches, hammering in steel plates, switching to bucket and excavating the bench.


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8.1.2 VENTILATION

If a positive pressure type ventilation ( blowing fan) is used a reduction of at least 20-25

minutes ventilation time, after blasting, can be realized by meeting and going through the

plug of blasting gas. This does, however, require that the crew is equipped with fresh-air

masks.

8.1.3 HANDLING WATER PROBLEMS

Surprisingly high contents of water at the face can be controlled by the following measures,

which also increases the loading capacity of the loader and increases support for the rails

laid. The dual digging blades can be swung out 90 degrees on each side from the centerline

and it is therefore very easy to dig drainage trenches in the muck. We further recommend

that, during the loading operation, a sump for a submersible drainage pump, type Flygt, be

dug in the muck, and placed a short distance behind the dozer blade of the Häggloader. Both

this pump sump and the drainage trench should be placed on the left side (operator’s side)

of the tunnel floor.

8.1.4 TRACK-LAYING AND TRACK-EXTENSION

If the blasted round is to be loaded by two or more trips by the shuttle cars we recommend

using Omega-extension sliding rails together with permanent prefabricated rail-sections of

10 meter length. The loader operator can, alone, advance the rail, during the transport and


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discharge portion of the train operating cycle, and be ready to load when the shuttle car set

returns.

If excavating the whole round in one go we recommend 3.3 meter jump set rails that are

later exchanged for 10.0 meter permanent rail sections during the drilling cycle. See figure

below.

Prefabricated rails sections can be transported hanging

on the sides of the shuttle cars.


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8.1.5 CONCRETE TRANSPORTATION

In many projects with extensive concrete lining, and where large volumes of ready mixed

concrete have had to be transported into the tunnel, our Shuttle cars have been used with

great success. In one project, Pampa de Majes in Peru, which is still to date the largest

irrigation project in the world, as much as 850.000 cubic meters of wet mixed concrete was

brought in by our Shuttle cars after the breakthrough in the tunneling itself was achieved.

Cars are easy to adapt for this type of operation and no deterioration due to separation or

hardening has been measured during the smooth and fast transports on rail.

8.1.6 DISCHARGING OF SHUTTLETRAINS

Various types of rush-plates can be fitted to the drawbar between train and locomotive.

Discharge can be done either to the side of the track, both sides, or between the rails.

Discharge time is calculated at 2 minutes per car.

Discharging to the side, center or both sides of the rail.


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8.1.7 COMPOSING A COMPLETE SET

A = Häggloader 8HR-2 or 8HR-5

B = Load car HRST-CLE

C = Train cars HRST-CTE

D = Drawbar for towing

E = Drawbar between Shuttle cars

F = Drawbar for towing/unloading

G = Wear plates 500 HB

H = Track gauge determined for each application

J = Voltage/frequency of electrical system

Determined for each application

CONCRETE TRANSPORTATION

The concrete mixing silos BMST 2 and BMS 6 with a capacity of 2 or 6 ma respectively enable

the concreting rate in tunnel construction to be increased considerably. They are employed

as mixing transfer stations and can store large amounts of concrete and feed it out

continuously in accurately metered quantities in conformance with the placing rate.

Dry-batched concrete supplied in hopper wagon trains can, for example, be mixed on site.

Thus, where transportation times are long it is possible to produce concrete satisfying the

standard specifications. In conjunction with agitators, these units contribute substantially to

reducing the cycle times since the agitators can discharge without mixing. Mixing is done in

the mixing silo.

The BMS 6 can be charged directly from trucks and is thus an interesting item of equipment

for tunnel construction. The mixing silos can readily be combined with tunnel pumps to form

compact units. These units have been successfully employed in a number of countries for a

variety of tunnel and gallery projects, e.g. for the Talave tunnel in Spain.

A special application for SCHWING concrete mixing silos in tunnel construction is their use as

truck mixer.

The 3 photos on the right show type BMST 2T in a 13 km long sewer tunnel in

Goteborg/Sweden. The top photo shows the silo filled with concrete on its way to the site.


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The photo bottom right shows the narrow passage with a width of only 2.8 m and a height of

3 m. The photo bottom left shows the discharge of concrete into a dumper in accurately

controlled quantities. In transit the concrete is kept in a plastic state in the drum.


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8.1.8 SHOTCRETE PROCEDURE


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8.2 SHAFTS

The work will be carried out inside tunnel or from the ground surface for pressure shaft construction

of the Nagdar HEPP according to Project’s need. For this project, RHINO 1088 DC Raise Boring

Machine will be used.

The raise boring process will be utilized in the excavation of the vertical holes with the following

advantages: safety, rapid setup and the results with better quality than other processes which

require longer time for execution and extensive labor, have higher operational risks and are

antiquated procedures.

8.2.1 GENERAL CONDITIONS

8.2.1.1 This proposal is based in the understanding that the compression of the

strata does not exceed 150 Mpa (Mega Pascals) or 21,750 PSI.

8.2.1.2 The project is designed with one vertical hole which will be excavated

with the raise boring system. The pressure shaft will be excavated in the

Headrace Tunnel from the level of 1930 meters to sublevel of 1500

meters approximately. The length of the pressure shaft will be about 430

meters (according to the projects) and the diameter will be 2,80 meters.

HOLE LENGTH

(m) ANGLE

RAISE BORING

DIAMETER (m) LOCATION ELEVATION

1 430,00 90° 2,80 PRESSURE

SHAFT

FROM - TO

1930 - 1500

8.2.2 The Main Steps In Raiseboring Operation Site preparation;

8.2.2.1 Site Preperation; A flat concrete pad foundation shall be prepared for the

Raise Boring Machine. Once the exact site and boring angle of the raise

has been established, the pad for the raise drill can be prepared. The


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recommendation is to make it out of concrete which should be sufficiently

strong to withstand the machine weight and any extra load caused by

reaming. The flatness requirement for the plane is ±3,0 mm/m. The

concrete pad must be poured directly on firm rock. All loose material

should be removed from the foundation surface before pouring the

concrete.

A small water reservoir (sedimentation pool) shall be prepared for the flushing water.

The machine base plate shall be anchored to the concrete foundation with rock bolts.

8.2.2.2 Transportation and machine assembly: First step shall be to transport the

base plate and the power supply units to the shaft location.

Raise Boring Machine shall be transported by its special crawler to shaft location and attached to the

base plate.

Raise Boring Machine shall be aligned in the direction of pilot hole by the surveyors.

Storage site for drill rods shall be prepared; drill rods and other drilling accessories shall be

transported to the drilling site.

CRAWLER AND RAISE BORING MACHINE – RHINO 1088 DC


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8.2.2.3 Pilot Hole Drilling:

The pilot bit is connected to the starter sub with a check-valve and the sub is connected to the first

stabilizer. Flushing hoses shall be connected.

During pilot hole drilling, flushing medium is used to carry up and displace the excavated material

from the hole. The alternatives (if necessary) for flushing medium are compressed air, water, a

mixture of air and water, and mud.

In normal conditions, water flushing gives the best boring efficiency. In addition, no air borne dust is

produced when water flushing is used. The easiest way to execute water flushing system is to have a

closed circuit from a sedimentation pool to the Raise Boring Machine. Water shall be pumped from

the pool, through the machine and the drill rods to the pilot bit, and the outgoing water and the

cuttings shall be lead (pumped) back to the pool; where the debris can settle and the clean water is

re-cycled.

PILOT BIT

8.2.2.4 Pilot Hole Break-Through - Reaming Preparation:

When the pilot bit breaks through, the pilot bit and some of the stabilizers from the drill

string shall be disassembled. The rock face at the break-through point should be as close to 90

degrees as possible. In most cases the rock face has to be trimmed straight and made perpendicular


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to the pilot hole. The reamer head shall be connected to the drill string and the thread connection

between the stem and the stabilizer is made up with the correct torque.

8.2.2.5 Reaming:

Reaming shall be started with a low rotation speed and low reamer force until the collaring is

completed. When the machine is rotating the cutterhead and pulling it against the face; the rock is

broken by tungsten carbide inserts on freely rotating cutters mounted on the reamer head. Most of

the premature cutter and stem failures are caused by poor collaring, i.e. too high feed force and

rotation speed have been utilized in this stage.

When the reamer head is boring with the whole diameter, net advance rates can be brought to

normal levels, i.e. 0.5 to 2.0 meters per hour depending on diameter and rock mass conditions.

REAMER

8.2.2.6 Finishing the Hole:

With modern machines, the reaming is carried out all the way to the machine. There are two

alternatives to finish the hole and disassemble the reaming head (cutterhead). In the first alternative

cutterhead has to be lowered all the way down to the shaft and cutterhead will be disassembled at

the sub-level. This alternative may cause an additional week of working time to finish the hole.(opt. I)

In the second alternative, the reamer head is fastened with a chain to a beam placed above the raise


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and the thread connection of the stem is opened. (opt. II)

Machine and base plate are dismounted and transported to the next hole (if available).

The possible uncut edge (for inclined holes) is sliced away and the reamer head can be lifted away

from the top of the raise. In this Project THE CONTRACTOR will prefer and organize the site

preparation according to option II.

COMPLETED RAISE BORE HOLE


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8.2.3 SERVICES GIVEN BY THE CONTRACTOR FOR RBM WORKS.

8.2.3.1 Personnel

THE CONTRACTOR will execute the shaft construction with correct, efficient and safe Raise Boring

operations by providing personnel with adequate raise boring experience.

Personnel required are as follows:

RBM Engineer (1 person)

Electrician & Hydraulic Specialist (2 person)

Raise Borer Machine’s Operators (2 person)

Raise Borer Helpers (4 person)

8.2.3.2 Machine and necessary equipment.

For this project it is planned to use the RHINO 1088 DC Raise Borer Machine, with all the necessary

drilling equipment, drill pipes, stabilizers, reaming head, cutters and pilot bits. (For more detail see

the subject “Work Description”).

TYPICAL ARRANGEMENT RBM SITE

INSTALLATION AND WORKING PLATFORM ON SURFACE


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TYPICAL ARRANGEMENT RBM SITE

INSTALLATION AND WORKING PLATFORM IN TUNNEL

8.2.3.3 Communication

Daily operation reports shall be presented to the Engineer in order to inform the Client regularly.

Hand held radio will be used for site communications.

8.2.3.4 Lubricants and Consumables

All the necessary lubricants and consumables needed for the proper performance of the assigned

work shall be supplied by THE CONTRACTOR to the construction site.

8.2.3.5 Personnel Protective Equipment.

All the necessary personnel protective equipment including a mining lamp shall be supplied by THE

CONTRACTOR to his personal.

8.2.3.6 Additional

Adequate water source (1.200 lt/min.) is required for piloting and reaming.

THE CONTRACTOR will use recirculated water by the sedimentation water tank.

8.2.3.7 Survey Service

Site surveyor is required to provide all necessary topographic surveys and measurements for correct

positioning and alignment of the RBM.


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DRILL RODS

8.2.4 SITE REQUIREMENT FOR SHAFT EXCAVATION BY RBM

All services described below shall be provided by the Contractor with sole responsibility and any

costs that may represent.

8.2.4.1 Source of 1.200 lt per minute of clean industrial water for cooling the

hydraulic system.

8.2.4.2 For the cleaning procedure of the piloting process, water is required for

the cleaning of debris during the piloting procedure at a rate of 1000 -

1200 lt/minute. Two 10,000 liters ponds are required for the piloting

procedure as well or 2,000 a 2,500 CFM compressed air to 100 PSI (If

necessary). Use of air is required when the rock strata is unstable or has

swelling characteristics.

8.2.4.3 The required energy is 440 volts (V) _400 Kva _ 630A in 03 phase plus a

ground wire. The RB machine will be connected to an electrical supply


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board which will be installed at a maximum of 3 meters away from the RB

station.

8.2.4.4 Lifting equipment with the load capacity of 16.500 kg (without crawler)

will be required for the loading and unloading of the RB machine.

8.2.4.5 To transport the Ø:2,80 meter reaming heads, it is required a lifting

equipment with a load capacity of 10,000 kilograms.

8.2.4.6 Sufficient lighting at the RB station and at the bottom of the whole for

inspection and connecting the reamer.

8.2.4.7 Ventilation of the RB work station and at the bottom of the hole is

required to remove dust particles in the air.

8.2.4.8 Accessibility, guarding and dewatering at any time and at any job shall be

provided.

8.2.5 Technical Services

8.2.5.1 Detailed specifications of the drilling program as well as geological

lithological and construction before the commencement of the work

program.

8.2.5.2 The services of a rigger to supervise the transport, handling, lifting of the

Raise Borer machine and it accessories is required.

8.2.5.3 Topographical services, to determinate the location, direction and angle

of the Raise Borer machine. Also the topographer has to mark the work

points (coordinates), start point and arrival point of the pilot hole and

supplies THE CONTRACTOR the respective protocol.

8.2.5.4 Construction of the chamber for the RB machine must have a 9.0m width

x 20m length and 6m height. The roof/back must be supported with rock


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bolts and wire meshing.

8.2.5.5 The cement pad required for the installation of the Raise Borer machine is

9m x 20m x 0.30m (minimum) of thickness. A previous inspection by THE

CONTRACTOR personnel of the cement pad. It must not have rebar, and

poured on top of solid rock and resistance of 250 kg/cm2.

8.2.5.6 Facilitate the transportation of the Raise Borer machine, accessories and

spare parts when it is required by THE CONTRACTOR.

8.2.5.7 In case it is necessary to use cement, chemical additives (polymers) or

muds for the drill, the supply of these materials shall be done.

8.2.6 DESCRIPTION OF THE WORK.

Raise Borer Machine to use.

Raise Borer model RHINO 1088 DC drilling accessories (drill pipes, stabilizers, reaming head, cutters

and tools).

Nominal diameter capability 0.66m – 2.80 m

Pilot diameter capability 12 ¼ “

Nominal length capability 600m

Total power installed 300 kw (400kVA_400V_630A)

RPM Pilot / Reaming 0-40 / 0-12 rpm

Reaming driving force 4.000 kN

Maximum Torque 300 kN-m

Angle adjustment 45⁰ a 90⁰

Description Dimension

Machine width 2.89 m

Height of the machine extended 5.32 m

Machine depth 2.18 m

Machine weight 16.500 kg


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Ø: 2.80m reaming head weight 12.000 kg

Drill Rod Diameter & Length 254mm & 1524mm (274 pcs)

Stabilizers Diameter & Length 311mm & 1422mm ( 9 pcs)

Pilot Bit Diameter 311mm

Transportation of RBM by Crawler: Transporters are used for getting the derrick to and from the

boring site. Additionally the transporters are equipped with hydraulic cylinders for derrick erection

during system setup and derrick take-down after completion of the raise.

Total set up time is a few hours, instead of the several days required for traditional raise bore drilling

equipment.

8.2.6.1 Drill String; Drill rods, stabilizers and pilot sub are all called drill string.

8.2.6.2 Drill Rods; For different machine sizes there are different drill rod. The

present standard drill rod sizes are produced by manufacturer. THE

CONTRACTOR will use 10″ (254mm) diameter drill rods.

8.2.6.3 Stabilizers; The stabilizer diameter is the same as the pilot bit diameter

and for 10" drill rods 12 ¼″ stabilizers and pilot are selected for

application.

8.2.6.4 Pilot sub; The pilot sub is the connecting piece between stabilizers and the

pilot bit. The male thread is standard DI-22 and size according to the

stabilizer thread and the female thread is standard API for pilot bit. Also a

check-valve is mounted inside the pilot sub. The valve prevents the

flushing media and the cuttings from going up the stabilizers during the

periods when the flow is off.

8.2.6.5 Cutterhead and Cutters; In normal raiseboring where back reaming is

done upwards, the crushed rock from the face falls on the head and goes

through the openings in the head and falls down the raise.

Normally the head is equipped with wings to push the wet muck behind the head. Reaming heads


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are equipped with a stabilizing system, i.e. rollers on the gage of the head support against the hole

wall. This will diminish the load and wear on stabilizers and it will also help to keep reamer in

alignment with pilot hole. Cutters used in vertical raiseboring are normal serial production

raiseboring equipment.

8.2.6.6 Muck removal; The first part of mucking is already taken care by the

cutter head, which has jet nozzles for flushing the face and scraping wings

to transport the muck behind the head. Mucking arrangements after the

reamer head depend on the circumstances:

Inclined holes: If there is any inclination, water flow can be used for mucking. Water brought to the

head through the drill string will flush the cuttings out from the hole. For large diameter holes or in

more shallow angles additional water can be pumped through the annulus between the pilot hole

and the drill rods or it can be provided with a separate hose which follows the head.

8.2.7 Performance expected

8.2.7.1 The performance expected will be directly related with the type of the

rock and its abrasiveness, hardness, geological faults and angle of drilling.

Core samples are required in order to get closer estimates of penetration

rates.


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8.2.7.2 This ensures operation of the RB machine at 83% of the total scheduled

hours. The 17% left over are for preventive maintenance.


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PILOT AND REAMING STAGE


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7.3 SHOTCRETE LINING SERVICE

The contractor will use remote control shotcrete machine for 5 cm thickness shotcrete

spraying construction under below listed terms and conditions.

Shotcreting shall be done in from top to bottom of shaft. This operation shall be done

with remote control shotcrete machine.

Suitable rock bolting as required shall be done in moderately jointed and good rock

reaches of shaft which shall be grouted in position after complete full of stell fibre

reinforcement shotcrete (SFRS) application.

Raise bore hole

Attached pictures of the shaft lining equipment are shown here for your information.

The collar of the hole is barricaded with fencing and can only be accessed by

personnel with full body harness and fall arrestor.

All equipment operation is controlled from the inside of a purpose built operator

control station. All control is communicated via broadband interface (antenna) in line of sight

function. Emergency stop back up is also hard wired to the control system. All robotic control

is calculated and self-adjusting to allow finite spray control. Computer control also operates

air, water and monitors all electrical systems on the winch deck. Robotic shotcrete application


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is monitored through 6 Infra-red fixed cameras positioned on four corners of the robot head

and can be recorded onto DVD.

Equipment required to support Shaft Lining is a 400V 120Kva generator with a

minimum 1200cfm compressor to convey the dry mix shotcrete over the distance.

Steel fibre reinforced shotcrete required for the works is to be supplied from the

nearest dam site batching facility and conveyed via an agitator with a minimum mixing bowl

capacity of 5m3. The shotcrete is added at the hopper of either a Rockcrete or Reed pump and

conveyed through 2.5” gunite hoses down to the robotic spray head.

Both shafts will be pre and post scanned using a video camera which conveys high

definition imagery to a hard drive for client inspection. Cameras are positioned on the robotic

spray head.

Pressure / Surge Shaft- Vertical Pressure Shaft is to be sprayed at 50mm thickness

coverage for entire length of shaft. Proposed duration for these works is 30 days and 10 days

respectively assuming day shift only spraying at minimum supply of shotcrete at 12m3 per

day.

Remote Control Shotcrete Lining Unit


CONSTRUCTION WORKS

Shotcrete application by using remote control spraying machine


CONSTRUCTION WORKS

7.4 CONCRETE LINING SERVICE

Climbing shutter system will be used for 15 cm thickness concrete lining construction

including reinforcement if necessary.

Shaft Concrete Lining Crane System

Shaft Platform will be used for the installation of the wall formworks and also to

create a safe working platform for workers.

Shaft platform beams are produced of NPU 100 (or equal) cast iron beams and

installed to the wall with the shaft platform pawls. Shaft platform pawls are seated into culvert

boxes which are left on the wall

During the formwork circulation the platform is moved in the vertical direction by

pulling inward shaft platform pawls with help of cranes.


CONSTRUCTION WORKS

Shaft walers are settled on reservations on wall to provide shaft platform. Then wall

formwork are settled on shaft platforms.


CONSTRUCTION WORKS

After first concreting process for further concreting wall formworks are taken and then Crane

moves platform upwards easily. In the same way concreting process goes on.


CONSTRUCTION WORKS

Concrete Pouring Method

Surge Shaft: The concreting of Surge Shaft is proposed to be carried out by

deploying a climbing form shutter. The installation time for climbing form

shutter will be about two weeks. Concrete mix shall be transported from

batching and mixing plant to near Surge Shaft through transit mixers feeding

40 m3/h concrete pumps for concrete lining up to top of shaft height from

bottom of Surge shaft. Climbing form shutter provide for casting concrete

around 4 meters length.

Shutter vibrators and needle vibrators shall be used for vibration of concrete.

The installation time for climbing form shutter will be about 1 week. The

progress with climbing form shutter will be of the order of 80 m / month and it

will take about 1 month to complete the operation of concrete lining of 35 m

deep Surge Shaft. For providing reinforcement a separate platform will be

erected which will move ahead of concrete lining.

Pressure Shaft: The concreting of Pressure Shaft is proposed to be carried out

by deploying a climbing form shutter. Shutter length will be 3 meters when the

system will working from bottom to upward through Pressure Shaft. We are

planning to increase length of shutter from 3m to 4m when the system will

working on downward direction. Concrete mix shall be transported from

batching and mixing plant to Pressure Shaft through transit mixers feeding 40

m3/h concrete pumps for concrete lining up to 100 m height from bottom of

Pressure shaft. Concrete lining in rest of the Pressure Shaft shall be done from

top of Pressure Shaft. Shutter vibrators and needle vibrators shall be used for

vibration of concrete. The installation time for climbing form shutter will be

about 1 week. The progress with climbing form shutter will be of the order of

90 m/month and it will take about 5 months to complete the operation of

concrete lining of 430 m deep Pressure Shaft. For providing reinforcement a

separate platform will be erected which will move ahead of concrete lining.


CONSTRUCTION WORKS

Consolidation Grouting: In order to prevent any loss of water through shear

seams and open joints it is necessary, especially in reach where rock cover is

limited, to carry out consolidation grouting. Consolidation grouting shall be

done according to technical specification.

On the other hand if the Client approves, for grouting purpose it is suggested

that around of the shaft border three pieces (each of 120 ° around shaft) long

holes drilled along shaft depths for consolidation grouting of around theoretical

line of shaft.

The most problematic unstable areas in overburden are commonly encountered

near the bedrock (hard rock base). Continuous ground water flow and

movement of rock layers results in abundant fracturing and weathering at this

location.

Some features can be recognized as especially threatening to shaft

stability:

► Joints filled with poorly graded materials,

► Clay gouge and other soft or soluble materials in the joints,

► Open joints,


CONSTRUCTION WORKS

► Smooth, slicken sized joints,

► High water pressures

► High residual stresses

In areas where joint planes threaten shaft stability and where water

flowing into the shaft is a problem, if necessary shafts should be treated with

pressurized grout.

Grout Penetration:

Grout selection is most important for increase it effect to shaft

stabilization.

► Joints > 1 mm with normal portland cements should be use

► Joints > 0.1 mm with ultrafine cement grouts should be use

► Joints < 0.1 mm with polyurethane/silicate grouts should be use

► For wide and unfilled joints where water wash is a problem, use hot

bitumen

► For narrow and filled joints where water wash is a problem, use

polyurethane foams.

On the other hand after shaft excavation If necessary should be re-drilled on

selected points up to required depth and consolidation grouting carried out

through these holes at a adequate pressure. The grouting in this case also is to

be carried out till refusal.

Constructo de safto la tunl- Yennigum Company

Documents

excavation speed

underground excavation

excavation process

ground support works

advance lengths of excavation

tunnel geology

tunnel entrance

method principles of