Tunnel boring machine

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1. ADVANCE CONSTRUCTION TECHNOLOGY SUB :- TUNNEL BORING MACHINE PREPARED BY :- CIVIL SEM :- 6 RUTUL DAVE (120770106082)

2. INTRODUCTION A tunnel is a horizontal passageway located underground. Tunnels are created by the process called excavation. There are many different ways to excavate a tunnel, including manual labor, explosives, rapid heating and cooling or a combination of these methods (conventional method). But all the above described methods can be hazardous in some way and hence are not risk-free. ‘Tunnel Boring Machine(TBM)’ is the best solution found by human to get rid of problems which can occur while excavation.

3. Tunneling Methods 1) Excavation by the Machines and Labors… IMG:1 IMG:2

4. Tunneling Methods 2) Drill and Blast: IMG:3 1 2 3 4 5 6 7 8

5. Tunneling Methods 3) Cut and Cover… IMG:4

6. Tunneling Methods 4) Tunnel Boring Machine (TBM): IMG:5

7. I ntroduction of TBM Tunnel boring machines are used to excavate tunnels with a circular cross-section. They can be used on any geologies. It can bore tunnels of diameter 1-20 meter. It made tunnel boring process risk free. IMG:6

8. Construction of TBM A tunnel boring machine (TBM) consist of 1 or 2 shields (Large metal cylinders). At the end of shield, a cutting wheel is attached. Behind the cutting wheel, there is a chamber and inside it there is a set of hydraulic jacks which push the TBM forward. Behind the shield, at the finished part of the tunnel several support mechanisms such as control rooms, rails for dirt removal, slurry pipelines etc., can be set up.

9. Construction of TBM The cutting wheel usually rotate at a speed between 1rpm and 10rpm. The rotation speed is determined by engineers depending upon the geology and diameter of the tunnel. The mud formed while drilling is removed either by making it a slurry and then through pipelines or by using a conveyer belt or rail system.

10. Procedure…

11. Hard Rock TBM IMG:7

12. Hard Rock TBM In hard rocks either shielded type or open type TBM can be used. For an open type TBM, no shield will be there. The TBM ’s disc cutters create compressive stress fractures and causes the rock to chip away. The chipped rock particles are called muck. Muck is removed through openings in cutter disc to conveyer belt system, which removes it from the tunnel. Facility to lay supports such as ring beams, steel strips, wire mesh etc., are provided in Hard Rock TBM.

13. Soft Ground TBM They are of 2 types: IMG:8 Earth pressure balance machine (EPB): EPB is used in ground with less than 7bar pressure. It use a combination of a disc cutter and cutting bits, Both made of Tungsten Carbide . EPB is capable to hold on soft ground by maintaining a balance between earth and pressure.

14. Soft Ground TBM SS is used in places where there is high water pressure and large amount of ground water. It is of a fully enclosed type. It mixes the mud with the Bentonite (Absorbent clay) slurry supplied and expels it through slurry pipelines. Large Slurry separation plants are provided on ground surface to separate slurry and mud, and slurry is recycled back to tunnel. 2) Slurry Shield (SS): IMG:9

15. Tunnel Boring Machine Facts Weight : 800 tons Length: 430 ft Motors : 350 hp electric motor X 8 nos. Energy required : 50,00,000 watts(@ max output) Cutter edge : 22ft dia, 60,000 pounds max thrust. IMG:10

16. Advantages of a TBM Structural stability and safety at the face and work area. Continuous(non-cyclic) and fast operation. Consistent, less skilled and easily trained operation. Safer and pleasant working environment than D& B. Less labors needed.

17. Disadvantages of TBM High cost due to the need of supporting things such as conveyer belt, rails, slurry separating plant, slurry pipelines….. Etc,. High cost of associated supplies.(Drill bits, TBM cutters, Blasting agents, …… etc,.) TBM excavation rates are 4 to 6 times higher than D&B excavation.

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