QATAR TRADING & CONTRACTING GROUP

TUNNELING DIVISION

GENERAL PRESENTATION FOR MICRO TUNNELINNG TECHNIQUE

www.qtcgqatar.comTel: +974 467 8066

Fax: +974 44663869E-mail: qtcg@qatar.net.qa

Jamal@qtcgqatar.comDoha- Qatar, P.O.Box: 9887 1

INTRODUCTION:Due to the requirement of installing pipe line under the ground by Non–disruptive method or Trenchless method to overcome surface disruption to the traffic and public utilities, QTCG is employing one of the updated technologies of Micro tunneling system made by Herrenknecht/ Germany , which had been used successfully in several projects at the state of Qatar since year 2003

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DIFINITION & PRINCIPLE:Microtunneling is a process that uses a remotely controlled Micro tunnel Boring Machine (MTBM) combined with pipe jacking technique to directly install product pipelines underground in a single pass. The jacking pipe is pushed behind thrust boring machine from a starting shaft or Launch shaft by the main jacking station located in drive shaft up to the target shaft or reception shaft. At the same time an unmanned, remote controlled microtunneling machine carries out the excavation at the tunnel face, the excavated material to be transferred by hydraulic conveying system (Slurry system) outside the tunnel and to the separation system at ground level. All these activities can be done while the operator is inside the control cabin monitoring and controlling the parameters.

APPLICATION:The major applications for pipe jacking and Microtunneling Include new sewerage and drainage construction, sewer replacement and lining, gas and water mains, oil pipelines, electricity and telecommunications’ cable installation, and culverts.

The technique can be used to negotiate obstacles such as motorways, railways, rivers, canals, buildings and airfields in the path of pipe laying projects; to minimize the surface disruption frequently associated with open cut pipe laying methods in urban areas; or simply to provide a permanent underground tunnel construction.Construction methods are available to cope with both cohesive and non-cohesive soils in dry or water bearing conditions. Excavation techniques are also available for jacking through rock or mixed ground conditions.

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Why Microtunnelling? No major trench excavation & backfilling.

Less surface disruption. No traffic obstruction or road closures. Less inconvenience for residents and shops. Less amount of excavation to be handled and disposed. No Requirement to dewater. No effect on the ground water. No requirements for utility diversions in urban areas. No Noise and dust pollution. No expensive reinstatement cost of asphalt or other surface. Can always take the short cut route. High accuracy installation in line, level, gradient. Less environmental disturbance to sensitive areas.

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MACHINERY AND EQUIPMENTS:Micro Tunnel Boring Machine “MTBM”. Control Cabin. Guidance System. Jacking Frame.Slurry Conveyance System. Separation Plant. Lubricant Mixing & Injection Plant. Electric Generator. Lifting Equipment.Mobile Store & work shop.

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TUNNEL BORING MACHINE:The Micro Tunnel Boring Machine with liquid conveyance system are applicable in almost every kind of geology, especially in non-cohesive ground material, even hard rock.The ground is excavated by a rotating cutting wheel in full section, thereby the tunneling machine is continuously advanced by hydraulic jacking cylinders . The driven cutting wheel can rotate in both direction. This offer the possibility to correct or to compensate a roll of the machine which occur as a reaction to the torque of the cutting wheel.

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CUTTING WHEEL:For material excavation whilst jacking proceeds the MTBM equipped with a cutting wheel different design and configuration of cutting wheel depend on the type of ground or soil to be excavated so there is mainly cutter for soft soil, mixed soil, and hard rock ground condition.Each type of cutting wheel have different configuration of scrapper tools and cutting discs.

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CONTROL CONTAINER:Each container with individual compartments separating hydraulic power pack from electric pane while operator and control room protected in its own space.

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CONTROL ROOM:The following function can be controlled, monitored, start , stop and adjust from control room:Hydraulic power pack (start/ Stop). Tunnel Boring Machine (Start/ Stop).Cutting wheel rotation (right/Left).Cutting wheel (RPM & Torque Increase/ Reduce).Guidance system (Monitor Position of MTBM).Steering cylinder (Monitor & adjust if required).Slurry conveying system (Start/ Stop/ Adjust).Jacking frame (extend/ Retract/ Speedup/Slowdown).Bentonite Lubricant station (Start/ Stop)

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GUIDANCE SYSTEM:It consists of fixed portion which is the electronic laser fitted at starting shaft and the moving portion which is the electronic target fitted at MTBM.

The laser target helps to control the tunneling machine. It records the position of the laser beam and sends the data via cable to the computer mounted in the control panel of the control container. On the computer display show the actual horizontal and vertical position of the tunneling machine, from there the operator can take corrective action by changing the steering cylinder position if required.

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Deviation and Tolerance:

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JACKING FRAME:Required to produce the jacking force needed to push the MTBM and the jacking pipes into the ground to a reception shaft. Consist mainly of steel frame equipped with hydraulic jacking cylinders, push ring, a rear plate and a base frame. The push ring transmits the force from jacking cylinder to the pipe bell, the rear plate supports to the shaft wall and the jacking cylinders are intended for advance. Different design with different dimensions and capacity to suit different size of Jacking pipes and drive length.

255 Ton Jacking Frame for jacking pipe OD 765mm.

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850 Ton jacking Frame for jacking pipe OD 2400MM

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SLURRY CONVEYING SYSTEM:The Conveyance circuit consists of feed and discharge slurry pumps, settlement tank and the necessary hoses and pipelines. Two flow meters, one in the feed line and the other in the slurry line, are installed for controlling the flow rate. When running the feed pump clean water will be flow into the excavating chamber via the feed line. In the excavating chamber the water will be mixed with the excavated material. The running slurry pumps pump the mixed water via the slurry line into a sedimentation tank or a separation plant. Excavated material will be separated from the water and the water flows back into the water circuit.

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SEPARATION PLANT:Its mainly used to separate the soil excavated particles out from the slurry, the main components of the separation plant are: Coarse screen for intercepting stones . Storage tank under the coarse screen.Cyclone with cyclone feeder pump for removing fine particles.

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Lubricant Mixing & Injection Plant:The lubricants of the jacking wall is very important to keep the pushing force low as possible to allow advance the line from the main jacking station, for this reason we are using a Bentonite powder to produce a lubricant. The Bentonite mixture acts as lubricant and tunnel support medium in the pipe jacking process. The suspension is mixed in a special jet mixer plant at job site and is pumped via Bentonite pump through Bentonite hoses into the tunnel. There the suspension is pressed through injection nozzles in the machine can into the annulus gap which is created by the diameter difference between the tunneling machine cutting wheel and the concrete pipes, In case of long drives and suitable tunnel size for man entrance extra automatic Bentonite lubricant station can be added to jacking pipes at selected intervals to insure continuous lubricant to the full tunnel line, the station powered by compressed air and controlled from operation panel through special control cable.

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POWER SUPPLY:Usually diesel engine driven generator with sufficient capacity is available on site to produce the required power needed to run the following:

Tunnel Boring Machine Power pack. Slurry Feed and discharge pumps. Separation plant. Bentonite Mixing Injection Plant. Lighting system. Ventilation system if required. General power supply for power tools and work shop.

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Lifting Equipments.A crane with suitable lifting capacity will be located on the construction site full time to be used in the following activity. Mobilizations and set up of tunneling equipment.Lowering the Tunneling Machine to the driving shaft.Transport of jacking pipes.Lowering the jacking pipe in to drive shaft.Removal of tunneling machine from reception shaft.Some time we can use gantry crane to be sited over the driving shaft for continuously use to lower the required jacking pipes.

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Mobile Store & Work shop container.A mobile container frame acting as store and work shop is located in the construction site. The container is equipped with electric distribution board with 400V & 230V electric power supply to feed the site with required power for lighting, dewatering pumps running power tools, also safety equipment and first aid kit will be located in that container.A working bench with some tools like screw drivers, open wrench, torque wrench, pliers for different applications, special tools and instrument to deal with electrical parts.Shelf’s for storing consumable material, special instruments and power lines.

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CONSTRUCTION SITE:

Site layout. Drive shaft. Jacking Eye & Thrust wall. Reception shaft. Location & Spacing Between shaft. Site Activity. Boring Procedure.

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Drive Shaft:The starting shaft, and can be called jacking shaft, it forms as the starting point for all jacking activity, the following activity occurs at this location: Construction of thrust wall and Jacking wall. Installing Main Jacking station.Position the Tunnel machine for starting the drive. Installing the fixed portion of measuring system (Laser). Installing Jacking Pipes. Installing Shaft Slurry Pump.Connecting the required power lines, slurry lines to the MTBM.

The Dimensions of Jacking shaft depends on the size of jacking frame and the manhole need to be constructed.

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Jacking wall and entry seal:A Jacking wall contain a soft eye with bigger diameter than the tunneling machine

cutting OD will be constructed of concrete at the front of the jacking station to offer a safe entry for the machine, And to prevent slurry pressure blowing back in to the driving pit a seal ring will be fixed to the jacking wall, the seal itself made of rubber and it’s mounted in a steel frame work called the Launching seal.

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Reception Shaft.The jacking ends at the target shaft and it form exit of the tunneling machine, this shaft should be with a suitable dimension to remove the tunneling machine and to construct a manhole if needed, and the reception shaft should be clean from obstacles and free of ground water.The ground surface area should be large enough and stable to take the size and load of crane used to lift the Tunneling machine.

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Location Spacing & Number of Shafts.The location and number of shafts is subject to the design of pipe line

system, and the capability of tunneling machine, Some shaft can be used as jacking shaft only, other can be reception shaft only, some can be jacking and reception for previous drive, and in some cases we can use one drive shaft for jacking two lines at different directions.

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SITE ACTIVITY:

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Boring process for slurry type MTBM can be described as follows1. Excavate and prepare the driving shaft.2. Set up the control container and any other auxiliary equipment beside the jacking

shaft.3. Set up the jacking frame.4. Lower the MTBM into the driving shaft and set it up.5. Set up laser guidance system and the MTBM in the driving shaft.6. Set up and connection the slurry lines and hydraulic hoses on the MTBM.7. The main jack pushes the MTBM through the launching eye.8. After the MTBM is pushed into the ground, disconnect the slurry lines and hydraulic

hoses from the MTBM.9. Retract the hydraulic jacks.10. Lower a new pipe segment to the driving shaft.11. Connect the slurry lines and hydraulic hoses in the new pipe segment to the ones in

the previously jacked segment (or MTBM).12. Jack the new pipe segment and excavate, while removing the spoil.13. Excavate and prepare the receiving shaft.14. Repeat steps 8 to 12 as required until the pipeline is installed and MTBM reach

reception side.15. Remove the MTBM from the receiving shaft.16. Remove the jacking frame and other equipment from the driving shaft.17. Grout the annular space between the exterior pipe surface and the tunnel.18. In case of sewer applications, install manholes at the shaft locations.19. Remove shoring, lining, or casing from the shaft and backfill them.

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