Tunneling in hard rock, Tunnel Boring machine, Drilling and Blasting, Shapes of the tunnel, Types of tunnels. Construction Management (VJTI MUMBAI)

1. Tunneling in Hard Rock
• Presented by: Mayur .U. Rahangdale
• Subject: Advanced Materials and Construction
Techniques
• Branch: Construction Management

2. Introduction
• A tunnel is a underground passageway
completely enclosed except for openings for
exit, commonly at each end.
• Tunnels are feasible alternative to cross a
water body or traverse through a physical
barrier such as mountain, hills etc.

3. Why Necessity of tunnel arises?
• Maintenance cost of tunnel is much less than that of
bridge or a heavy cut.
• The main reason behind provision of a tunnel is to
eliminate a circuitous route for reaching the other
side of hill (the length of the railway line will be
considerably reduced).
• In large cities, tunneling would provide the most
rapid and unobstructed transportation (leading to
reduction in traffic congestion)
• Tunnels provides flat gradients in hilly areas.

4. Advantages of Tunnel
• For carrying public utilities like water or gas
,railway lines or roads across a stream or
mountain ,tunnels may be cheaper than bridge or
open cut.
• It is more efficient than bridges (as during wars it
is much difficult to destroy a tunnel compared to
bridge).
• It is generally assumed that when the cut
required will have a vertical depth exceeding 20
m ,it is less expensive to build a tunnel.

5. Classification of tunnels :-
1) On purpose
a) Traffic Purpose Tunnel
• Railway tunnels :- to carry Railway traffic.
• Highway tunnels :- tunnels used to carry roadway traffic
• Pedestrian tunnels: - tunnels used to cross pedestrian
traffic.
• Navigation tunnels: - tunnels used to navigate from one
point to another.
• Subway tunnels: - Tunnels constructed under the ground
for public traffic.

6. b) Water Conduit Purpose :-
• Penstock for hydroelectric Power plant.
• Water Supply Tunnel.
• Sewer Tunnels.
2) On type of ground
• Tunneling in hard rock.
• Tunneling in soft rock.
• Tunneling in quick sand.
3) On the position and alignment.
a) Saddle or base tunnel.

7. • Spiral Tunnel
• Off –Spur Tunnels
• Slope Tunnel
Fig – Spiral tunnel

8. Shapes of tunnels
• Circular shape tunnel
• D- Shape Tunnel
• D- Shape Tunnel
• Rectangular Shape Tunnel
• Egg –Shaped Tunnel
• Elliptical Shape Tunnel
• Horse –Shoe Tunnel
• Pilot Tunnel

9. Tunneling in soft Ground
Methods
• Fore poling Method
• Needle beam Method
• Belgian Method
• Austrian Method
• Army Method/ Case Method
• American Method
• English Method
• German Method

10. Tunnels in Hard Rock
• The major methods of tunneling in hard rock are :-
1) Heading and Benching Method (top and bottom or up and down
method)
• This method involves the driving of the top portion in advance of the
bottom portion.
• It is used when the tunnel section is very large and quality of rock is
satisfactory.
• In this method the top heading excavation is usually 3 to 4 m ahead of the
bench excavation.
• There is simultaneous drilling and mucking in this method.

11. 2) Drift Method
• Rock tunneling is sometimes carried out first in smaller section of the
proposed tunnel and then widened .This method is called as drift method.
• In drift method, the total c/s of tunnel is divided into n no. of square
section .Each section is about 2.5 to 3 m2 in area (face area).
• By converting the tunnel into small c/s part any part is selected for the
excavation which may be central part, top part, side part or bottom part.
• And through this part the excavation is done from start to the end .Such
excavation is called as drift.
• The drift provides the ventilation or light during the excavation of the
remaining part of the tunnel.

12. 3) Full face method :-
• In full face method, workers excavate the entire diameter of tunnel at
the same time.
• In this method the mucking track could be placed progressively along
with the excavation.
• In this method tunneling is continuous.
• Full face method was limited to small tunnels only, but now with the
improvements and development in tunneling equipment more and
more large tunnel can be driven by this method.
• One of the machine which is usually used for cutting the full –face of
the tunnel is called as Tunnel Boring Machine.

13. Tunnel Boring Machine
• The use of tunnel boring machine is on increasing way,
because instead of drilling and blasting this method can be
used conveniently.
• In case of tunnel boring machine the rock damage is less, cut
material is handled systematically, safety of workers is great.
• The cost of tunnel lining is reduced and the operation is
continuous with the help of TBM.
• With the help of TBM ,the face area that can be cut is about 20
m2
• The diameter of TBM is up to 6m.

14. HARD ROCK TBMS:
• The Hard rock, either shielded or open-type TBMs are used to
excavate rocks with the help of disc cutters which are
mounted on the cutter head.
• The rocks (muck) get chipped away as the disc cutter
compresses stress fractures on it.
• Now the excavated rocks are transferred to the belt conveyor
through the cutter head openings.
• These rocks are then run through multiple conveyors to get
them removed from the tunnel.

16. Drilling, Blasting and hauling of muck
Before the invention of the TBM drilling and blasting was the
only method of excavating the material through hard rock.
For drilling and blasting we follow following steps.
• Small diameter drill is made with the help of different
drilling equipment.
• The drill hole is clean for placing the explosive and packing
of explosive with clay.
• Plantation of certain explosive material is done in the drill
hole.
• Detonating the explosive.
• Fumes are released from the explosive.
• Final excavation or mucking of material is done.

17. Theory of drilling and blasting
• A drill hole normal to the face when exploded with proper charge
will break out a gap inclined at approximately 45 degree to the
face.
• If two similar holes are kept side by side and fixed together they
will blast a large quantity of rock which will be about 2.25 times
greater than the single faces.
• If three explosive with three similar holes are kept side by side and
fixed together than it will break 3.5 times greater than quantity of
rock than that for single face.
• An inclined cut hole is more efficient than the hole that is drilled
normal to the face. Therefore, an inclined angle of 45 degree is
made to the face of the rock and hole is drilled .With the help of
this inclined hole, the angle of crack also increases it the about 54
degree 44 min to the axis of the hole.

19. Drilling Equipment’s
• Drilling is the process of making holes using drilling equipment. The
drilling equipment varies w.r.t size of project, kind of rock, depth and size
of hole, nature of terrain, etc.
• The drilling equipment can be divided into two parts.
1) Percussion Drills
• A drill holes the drill bit and rotates it in partial manner/angle (90 or 120
degree) to provide axial force for making a hole.
• Percussion drill breaks the rock by impact from the repeated blows.
• The popular varieties of percussion type of drills are
a) Jack hammer
b) Tripod Drills
c) Stop Hammer
d) Drifter
e) Churn drills
f) Piston drills
g) Wagon drills

20. a) Jack Hammer
• It is the air operated percussion types of drill which is portable and hand
operated.
• It is most used for drilling vertical holes.
• The weight of the jack hammer varies from 10- 40 kg.
• It can drill the hole up to 5 m depth.
• The impact blow action of the jack hammer is about 2200 blows/min.
b) Tripod Drills
• This are similar to the jack hammer, expect that it is mounted on tripod to
provide sufficient stability.
• Tripods are usually very low and require drill changes every 1m or so.
• They are not much in use except for very hard rock.
c) Stop Hammers
• This is modification of jack hammer which are mounted on certain vehicle
to hold the drill against the work and are usually used for up holes.

21. d) Drifters
• The drifter is an air operated precaution type of drill similar to the jack hammer
but is so large that it needs mechanically mounting.
• They are used for drilling down ,horizontal or up holes
• They can drill up to of 12 cm diameter holes.
e) Churn Drills ( Well drills )
• They are also called are well drills.
• Churn drill can drill hole up to 15 cm diameter.
• Churn Drill can drill at any angle and has the penetrating depth up to 100 m.
• They are operated by steam or gasoline.
f) Piston Drill
• The piston drill is securely fastened and traveled the full length of the piston
stroke.
• It can drill a hole of 6 cm in diameter and can drill a hole up to 10 to 20 m long.
• The impact blowing action is about 200 blows per minute

22. f) Wagon drill
• The wagon drill is the drifter mounted on a vehicle to provide portability in
drilling the holes.
• They are used extensively to drill the holes up to 12 cm in diameter and up to
10 m in depth.
• Their performance is better than jack hammer.
• They can be used to drill the hole at any angle from down to up.
2) Abrasion drill
• The abrasion drill is a type of drill which grinds the rock up to small particles
through abrasion effect of bit that rotates in the hole.
• The common examples of abrasion drill are
a) Blast hole drills
b) Short drills
c) Diamond drills
a) Blast hole drill :-
• This is the type of rotary drill which works on the system of compressed air
and disintegrates the rock as it rotates over it.
• The type of abrasion drill is used for drilling the hole up to 100 m in depth.

23. b) Short drills
• This is the rotary abrasion type of drill which has the rough surface at the bottom
and makes the hole in certain rock by crushing it.
• Short drill can drill a hole up to 75 in diameter and up to depth of 200 m.
c) Diamond drill
• Diamond drill is a rotary abrasion types of drills whose bit consists of metal matrix
in which they are embedded a large number of diamonds.
• Diamond drills are uneconomical, hence are used in less quantity.

24. Blasting
• The blasting is the operation performs to loose the
rock so that it can be excavated or removed from its
existing position.
• Blasting is accomplished by discharging an explosive
that has been placed in a hole specifically drill for this
purpose.
• During the blasting operation the drilled holes are
made and cleaned, the charge of explosive is placed at
the bottom of blast hole or drill holes; remaining
portion of the hole is filled with the clay and tampered.
• The size of the explosive ranges from 2.5 to 20 cm in
diameter and its length is about 20-60 cm and
tampered.

25. Types of Explosive
a) Straight Dynamite
• It is the first type of explosive with which all high explosives are
compared for strength.
• Its primary constituent is nitro- glycerin varying from 15-60%
• They are highly water resistance and a desirable property for sub-
marine blasting.
• Because of bad fumes they have been replaced by other types.

26. b) Ammonia Dynamite
It contains equal parts of nitro- glycerin and nitrate of ammonia as the
explosive material.
They come in the strength of 15-40%, but are not so sensitive as straight
dynamites.
They are suitable for soft rock and fairly water resistance and their fumes
are not so bad.
c) Gelatin Dynamites
• They are of two types
 Straight Gelatin dynamites
 Extra or special Gelatin dynamites
• Both this type of gelatin dynamites consists of jelly of nitroglycerin and
nitro-cotton.
• In extra or special gelatin, part of nitro-glycerin is replaced by nitrate of
ammonia.
• Both these types are highly water resistance and their fumes are good.
• Their jelly like plastic consistency permits solid loading in a hole.
• They are quick and have high shattering effect.
• Because of these characteristics they are chosen for most rock tunneling
work.

27. d) Semi –Gelatin Dynamite
• In a recent development, consisting principally the complex compound of nitrate of
ammonia with same gelatin, nitro- glycerin, nitro – cotton, semi –gelatin is formed.
• Semi- gelatins are bulkier than the straight or extra gelatin.
• They are water resistant and fume quality is good.
• Because of their low density, they are cheaper than extra or gelatin dynamite used in soft
rock and lime –stone work.
e) Blasting Gelatin
• Blasting Gelatin are also a recent, fast, strong explosive.
• They have the consistency same like soft rubber and it is fully water proof.
• It is adaptable for wet work.
• Its fumes are extremely bad and its strength is about 100%
f) Other High Explosives
• Several Special high explosives are made, developed for special condition .Especially for
disintegration of hard rock.
• Some of the other explosive are
• TNT – Tri –Nitro- Toluene
• RDX –Rapid detorating explosive
• Pent – Penta Eny thital

28. Case Study on Maroshi - Ruparel
water tunnel
Location :- Mumbai ,Maharashtra

29. Introduction
Mumbai’s water network is crumbling under the strain. Its mains
system is at least 80 years old, the majority of it laid in the colonial
era. Though the city has seen some water distribution projects post-
independence, they were still more than 60 years old.
Much of the system works through surface pipelines, which are
prone to leakages and theft. This highly pressurized network is
further hindered by passage under slum land, which adds even more
complication to their maintenance. Likewise, Mumbai’s main water
line runs beneath the runway of Mumbai international airport,
making it doubly difficult to maintain, while a major burst could
affect the movement of air traffic into and out of the city.

30. Hindustan Construction Company (HCC) was awarded the Contract of Maroshi-
Ruparel College Tunnel Project by the Municipal Corporation of Mumbai in
September 2007 with a Contract value of Rs 415.10 crore. This is a Water
Supply Project executed under Jawaharlal Nehru National Urban Renewal
Mission (JNNURM) and is funded by the Government of India, Government of
Maharashtra & Municipal Corporation of Greater Mumbai.
The tunnel stretch is divided into three sections namely, Maroshi-Vakola (5.83
km long), Vakola-Mahim (4.55 km long) and Mahim-Ruparel College (1.86 km
long). Maroshi-Vakola tunnel stretch is the longest section of the Maroshi to
Ruparel College water tunnel.
The Maroshi-Ruparel tunnel work consists of construction of tunnel having
3.60 m diameter and 12.24 km long using Tunnel Boring Machine from
Maroshi connecting to Ruparel College. The tunnel is connected with Shafts at
Maroshi, Vakola and Mahim. The shafts are 12 m in diameter and about 80.00
m deep equivalent to a to 26-storey building deep into the ground. It will be
through these shafts that localities will get water supply.

32. The BMC began the underground tunnel project to stop leakage and
water thefts from the water pipelines .The other focus of the project is
to replace the water pipelines that are centuries old and have
corroded at several spots ,causing sewage water to mix with drinking
water.
The Vakola-Mahim section passes below the Mahim creek while the
Maroshi-Vakola section crosses both of Mumbai airport’s runways at
around 70 meters below ground level. The tunneling work was carried
out without disturbing any operations on the ground level.
The tunnel boring was extremely challenging due to heavy seepages
and varying rock strata. During monsoon, the tunnel seepage had
increased to about 25,000 m3 per day. Extensive grouting was carried
out to control the same.

33. PROCESS
First, a shaft with a diameter of 10 meters was constructed at a depth of
between 70 and 80 meters. This served so that contractors could deliver
all the necessary plant, machinery and equipment, including tunnel
boring machines (TBMs), locomotives, water pumps and concrete mixers,
through it to reach the 70-metre depth required for the boring and
drilling.
This was done by the gripping of jacks and alignment of TBM cutter heads
for boring at a width of 3.6 meters through the earth.
The concrete lining is cast on site rather than being pre-cast elsewhere.
Once a stretch of boring is complete, an epoxy-coated reinforcement layer
is fixed into place; the shutters and bulkheads are then set to pour ready-
mix concrete using the agitator cars.

36. Conclusion
• After completion, the tunnel improved the water situation in south and central
Mumbai by supplying 1,100 million liters daily. The tunnel replaced the old upper
Vaitarna and Vaitarna mains in this section. It improved the water supply to
Vakola, Mahim, Dadar and Malabar Hill significantly.
• This project is part of the rehabilitation and improvement of the drinking water
conveyance / distribution system from Bhandup Treatment Works to Western
Suburbs and Southwest part of the Mumbai city.
• BMC town planners expect the new tunnel to have a number of advantages over
the existing surface pipeline, because it travels at such great depth, meaning that
the structure cannot be tampered with, as is the case with surface pipelines. In
addition, there are fewer chances of leakages and water theft, and most
importantly, the tunnel is not expected to require major maintenance over the
next 100 years. And since the entire distribution system is made of concrete, it
will not corrode, invariably happens with surface pipelines.
• The project is also designed to withstand earthquakes.