1) Tunnel boring machines (TBMs) are used to excavate tunnels with a circular cross-section through various ground types and diameters ranging from 1-20 meters. 2) A TBM consists of one or two large metal cylinder shields at the front, fitted with a cutting wheel, and hydraulic jacks that push the machine forward as it removes material. 3) TBMs allow for safer, more consistent tunneling compared to conventional methods and reduce risks from manual labor or explosives, though they require more supporting infrastructure and have higher costs.

1. ADVANCE
CONSTRUCTION
TECHNOLOGY
SUB :- TUNNEL BORING
MACHINE
PREPARED BY :-
CIVIL SEM :- 6
1)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. Introduction 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
1) 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.