This document summarizes trenchless technology methods for installing underground pipes and cables with minimal excavation. It describes various trenchless methods for new installations like microtunneling, horizontal directional drilling, and guided boring. It also covers rehabilitation methods for existing underground infrastructure like pipe bursting and pipe eating to replace pipes without excavation. The objectives of trenchless technology are outlined as providing alternatives to open trench installations that are faster, safer, more reliable, and cause less disruption.

1. TRENCHLESS TECHNOLOGY
Submitted By:
Abhimanyu saraswat
Civil 4th
Year ‘A’
100107003
DATE OF SUBMISSION:- 29/11/2013
SUBMITTED TO:-
PROF. SATYA PRAKASH
HEAD OF DEPARTMENT CIVIL ENGINEERING
1)
TECHNICAL SEMINAR
REPORT

2. TITLE
“Trenchless technology” is a type of subsurface construction
work that requires few trenches or no continuous trenches. It is
a rapidly growing sector of the construction and civil
engineering industry.
2)

3. ABSTRACT
The objective of this study is to understand about the new
advancement in civil engineering that is Trench less
technology. It include methods like installing, repairing and
renewing underground Pipes and cables using techniques
which minimize or eliminate the need for excavation. It can
reduce environmental damage, Social costs and produce an
alternative to open trench method of installation, renewal and
repair .It includes in, development of all kinds of underground
napping techniques, tunneling devices and specialist materials
and equipment. Trench less technology is basically making a
tunnel below the surface and staling service lines like water or
gas pipes, electric or telecommunication cables without any
disruption to the public. It also makes it possible to install the
utilities under rivers canals and other obstacles with no
disruption of flow and with minimum or no damage to the
environment.
The methods to be used in new
installation Micro tunneling, Horizontal directional drilling ,Short
drive system ,Guided drilling.
This detail study will show us why it is more advantages to use
trenchless technology compare to all others.
3)

4. KEYWORDS
o Pipe jacking,
o pipe ramming,
o horizontal boring,
o horizontal directional drilling
o trenchless construction
o guided boring
o Pipe eating
o Retaining the existing pipes
o Localized repair
o Pipe bursting
4)

5. OBJECTIVES
 To find a substitute to conventional methods of digging
so that it is more easily, fast, reliable.
 To improve the serviceability of pipes and decreases
the maintenance problems.
 In brief, the objective of trenchless is to use it for Repair
& Retrofit of pipes, installation of new pipes, Reduction
of time, Structural safety & Reliability and Sustainability
& Environmental Protection.
 Transmission is made easy and effective.
5)

6. STATE OF KNOWLEDGE
The current state of trenchless technology in india is the
adoption of trenchless technology by Gas Authority of India Ltd
has extensively used this system in laying the gas pipe lines
from Gujarat gas fields to Northern India selectively for crossing
roads and railway lines. In the past water supply and sewerage
schemes were planned in Madras and Srinagar. But the
projects did not start due to political and economic
considerations.
Currently, in Mumbai a sewerage
project is under consideration using the micro-tunnelling
method. It is hoped that the Mumbai Municipal Corporation will
go ahead with the scheme soon. NBCC Ltd and its associate
firms are trying to popularise trenchless technology by laying
the MTNL fibre optic cables across roads and railway
lines by using trenchless technology equipment.
A technical committee under the aegis of NBCC Ltd will soon
bring out a ‘National Guidelines for adopting trenchless
technology in India’ similar to the ‘Yorkshire Code of
Practice for Microtunnelling’ and the ‘Guidelines compiled
by Louisiana Technical University, USA’.
6)

7. IMPORTANCE OF THE PROPOSED
SEMINAR
Traditional open cut trenches are in general use for laying the
underground services but have following inherent
disadvantages, which can be eliminated / minimised by
adopting the trenchless technology methods:
a) Traffic hindrance: Traffic obstruction, accidents, extra cost
in providing diversions and their maintenance etc.
b) Environment pollution: Dust and air pollution by vehicles
and machines, noise pollution to public, pollution of ground and
surface water etc.
c) Citizens and society: Increased cost in repair and
rehabilitating the roads, compensation for damages, advantage
of early availability of the utility and avoidance of public
hindrance etc.
Trenchless technology will prove competitive with its increased
use considering the social cost aspect in the project. For a
meaningful safe environment and public health in our cities the
application and adoption of this advance technology may soon
become imperative.
The seminar describes the few important methods for installing
utilities for infrastructural development under the ground.
7)

8. Methodology
Trenchless technology methods system have been categorized
in to two groups :
1) New installation
2) Rehabilitation and Renovation
NEW INSTALLATION:
Methods for installation of a new pipeline or duct, including
dealing with service connection are:
1) Micro tunneling
2) Horizontal directional drilling
3) Short drive system
4) Guided drilling
MICRO TUNNELING:
Controlled excavation – steerable –Less than 1000mm
diameter –Medium length
Micro tunneling is a term which is used to describe remotely
controlled mechanical tunneling systems where the spoil is
removed from the cutting head with in the new pipe line which
is advanced by pipe jacking.
8)

9. Micro tunneling machines have now been developed to work
from drives hafts in almost all types of ground conditions. The
cutting head has to be carefully selected to deal with the
expected ground conditions, with the appropriate cutting tools
and crushing devices for the range of gravels, sands, slits, and
clays.
The only excavating required from the service is for drive and
receptions shafts. Spoil may be removed from the face by an
auger running through the newly installed pipeline to a skip in
the base of the drive shaft.
Alternatively, water or bentonite may be used to convert the
soil into slurry at the cutting face. The slurry is less then
pumped to the surface where the solids are separated before
disposal .
Micro tunneling is used extensively for sewerage work where
surface disruption has to be minimized. Machines are now
available to drive 100mm or more in soft ground for sizes
100mm diameter upwards. from drive shafts of less than 3mm
diameter.
Micro tunneling system has been developed in which temporary
steel tubes are jacked in and removed at the next manhole
position, the new pipeline following in the established bore.
9)

10. HORIZONTAL DIRECTIONAL
DRILLING
Horizontal drilling systems are nowadays widely used for
installing pressure pipes under major obstacles such a motor
way intersections, large rivers and airports runways.
A small rotating and steerable drill
bit is launched from the surface at an angle 10-15 and is used
to drill 90mm mud filled diameter hole. During the drilling
operation a 125mm diameter washover pipe is drilled over the
pilot string and following some 100mm behind the head.
Alternate drilling then continues on the pilot string is removed
and the bore is enlarged by a rotating barrel reamer attached to
and pulled back by the wash over pipe, drilling mud being used
to llushed away the cuttings and to support the reamed hole.
Subsequent caming continues until required diameter is
achieved. The product pipe is less than attached to the reaming
head and pulled through the bore drives of more than 1.5km
and of up to 1200mm diameter have been carried out.
10)

11. SHORT DRIVE SYSTEMS
Auger boring utilizes a rotating head to excavate the soil, which
is transported by auger flights operating in a casing to the drive
pit. The head is recovered at an exit pit or in the trench cut for
the adjacent length of pipe line. Auger boring is used in the
range of 100-1000mm diameter
11)

12. AUGUR BORING
IMPACT MOLING:
In which a percussive mole is launched from a drive pit to
displace the soil and from a bore is widely used. The new
conduct is normally drawn in behind the mole. They are used to
install services for all utilities.
ROD PUSHING:
It is a technique in which a bore of about 50mm diameter is
formed by displacement. A rod is advanced by a straight
hydraulic push and the pilot hole may be back reamed to the
required size. The technique is used for the installation of pipes
and conduits up to 15mm diameter over lengths of 30-40mm.
PIPE RAMMING AND THRUST BORING:
It is similar processes where a casting, usually steel, is driven
through the ground from the drive pit to the exit pit.
Accumulating spoil is removed by compressed air and water
after completing the bore. Pipe ramming is suitable for most
types of soil but not suitable where there are solid rock
formations. It is said to be a cost saving alternative to open
trenching, angering or pipe jacking methods. Usually pipes up
12)

13. to 2000mm diameter can be laid using this technique
depending upon the equipment uses.
GUIDED DRILLING:
Guide drilling employs an excavation or soil displacement with
compact lightweight rig for rapid mobilization. Small diameter
jets mechanized cutting tools or displacement heads attached
to a flexible drill string are positioned to form a bore as the head
is thrust forward. The drilling head is launched from the surface
at an inclined angle. Controlling the orientation of a slant face at
the head effects steering in both vertical and horizontal planes.
Monitoring of the alignment takes place using a transmitter in
the head and a locating device at ground level.
Guided Drilling
13)

14. REHABILITATION AND
RENOVATION
Methods including are:
1) Pipe bursting
2) Pipe eating
3) Retaining the existing pipes
4) Localized repair
Mini Burst
14)

15. PIPE BURSTING:
In this method an existing pipeline can be replaced with a
pipeline of the same or larger dimension without opening up the
ground. It is especially useful in areas where the load on the
system is more than the existing pipe can handle and
replacement is required.
The method uses a mole as a bursting head
that is drawn through the existing pipe crushing it as it moves
forward and replacing it with a new PE (polyethylene) pipe. The
main advantage of this system is that a small power source can
be used to drive the mole with minimum time. Upsizing from
100mm diameter to 225mm diameter is now well established,
and pipes of up to 600mm diameter have been replaced.
PIPE EATING:
Pipe eating is an online micro tunneled replacement technique.
The existing defective pipeline is crushed and removed through
the new pipeline. Lateral connections must be disconnected in
advance and may be replaced by rider sewers or reconnected
by angled drilling.
RELINING THE EXISTING PIPES:
This method requires access, usually by manholes, at both
ends of pipe. A flexible liner is places into the defective pipe
and with the use of water under pressure finds its own way and
15)

16. can pass bends of 90o
. In places where joints have moved or
sections are missing, but the passage is available, the liner
creates a smooth transition. When the liner is in place, it is
heat cured to create a rigid, tough, and smooth inner surface.
LOCALISED REPAIR:
Local defects may be found in pipes due to cracking or joint
failures. Systems are available for resin injection to seal
localized defects in the range 100mm-600mm diameter.
Chemical grouting with urethane and similar materials are used
in sewer rehabilitation. Remote and man entry grouting of
defective joints and cracks may prevent infiltration in pipelines.
This is an inexpensive method of rehabilitating existing systems
up to several hundred meters of length everyday from manhole
to manhole.
PIPE SLIP LINING:
It is another method used that involves inserting new smaller
pipes in to older, damaged sewers thereby replacing the old
pipe. But the new pipe is in reduced diameter.
16)

17. MODIFIED SLIP LINING:
It often called close fit lining utilize the properties of PE or PVC
to allow temporary reduction in diameter or change in shape
prior to insertion in the defective pipe.
The method includes Roll down, Swage lining and
Deformed lining. The inserted pipe is subsequently expanded
to form a tight fit against the wall of the original pipe, thus
avoiding the need for annular grouting as in conventional slip
lining. For Roll down and Swage lining, temporary reduction in
diameter is achieved either by mechanical rolling (Roll down) or
drawing through a reduction die (Swage lining). For Deformed
linings, the pipe is deformed and folded immediately after
extrusion and is coiled on a drum. After insertion in the
defective pipe, the lining is expanded using steam and a re-
rounding device to form a close fit.
These systems are suitable where the existing line is of good
shape. As compared to conventional slip lining , in this method
there is little or no loss of hydraulic capacity.
17)

18. PRE-REQUISITES
Through surveys and site investigations are essential to the
success and efficiency of trench less installations and repair
techniques.
1) The survey results help top determine the most
appropriate systems.
2) The investigations methods include geophysical surveys,
boring and sampling, measurement of ground water table,
test pits and trenches, penetration tests, examinations and
investigations of existing structures using ground
penetration testing etc.
3) Closed circuit televisions, ground penetration radar, utility
detection equipments leak detection techniques are
available for below ground activities.
18)

19. The main trenchless techniques which are in use in India
(included in the above mentioned methods) are described
below.
DIRECTIONAL DRILLING:
Directional drilling involves steerable tunneling systems for both
small and diameter lines. In most cases, it is a two-stage
process. The first stage consists of drilling a small diameter
pilot hole along the desired centre line of a proposed line and in
the second stage, the pilot hole is enlarged to the desired
diameter to accommodate the utility line and to pull the utility
line through the enlarged hole. The pilot hole is of
approximately 3 inches in diameter and is drilled with a
specially built rig up with an inclined carriage typically adjusted
to between 5 and 30 degrees, which pushes the drill rods into
the ground. However the optimum angle is 12 degrees. As the
pilot hole is being drilled, bentonite-drilling mud is pumped
down the center of the drill rods. The drill head consists of
either a jetting head or drill bit. In the case of a jetting head,
small diameter high-pressure jets of bentonite actually cut the
soil and facilitate spoil removal by washing the cuttings to the
surface where they settle out in a reception pit. In case of drill
bit, the bit is driven by a down hole mud motor located just
behind the drill bit from energy derived from the pumped drilling
fluid. Before the start of back reaming the pipeline has to be
19)

20. positioned on rollers in line with the hole to minimize any axial
load on the line.
ADVANTAGES:
The major advantage is the speed of installation combined with
the minimum environmental and social impact.
1) Long and complicated crossings can be accomplished
with a great degree of accuracy since it is possible to
monitor and control the drilling operation so that utilities
can be fit into small corridors where little place is available
between existing utilities.
2) Another advantage is that sufficient depth can be
accomplished to avoid other utilities.
3) Limitation of access and reception pits is another
advantage.
DISADVANTAGES:
1) Special equipment and very high degree of operation
skill is required.
20)

21. 2) As the cost of the equipment and the operation are
high, bore length should be sufficient in order for it to be
economical.
3) Mainly steel pipe is being installed by the method.
RAMMING:
In this method, the pipe is rammed through the soil by using a
device attached to the end of the pipe to drive the pipe through
the soil. In this method, the tool does not create a borehole. It
acts as a hammer to drive the pipe through the soil.
Compressed air supplied from an air
compressor is generally used as a power source. When
ramming pipe, the leading edge cuts a borehole, the spoil
enters the pipe and is compacted as it is being forced to the
rear of the pipe. After the whole length of the pipe is rammed in
place, the tool is removed and the pipe is cleaned out.
The type of pipe installed by the pipe ramming method is
limited to steel due to the application of cyclic impact loads on
the pipe. The size of the pipe ranges from 2 inches to 55
inches. This method is capable of installing pipes to over 200
feet (60 meters) in length.
ADVANTAGES:
The pipe ramming is an effective method for installing medium
size pipes. The method is economic since the equipment cost
21)

22. is not very high and the operation is simple. The pipe can be
installed in one piece or segments. This can be used in almost
all types of soils. The method does not require any thrust
reaction structure.
DISADVANTAGES:
The major disadvantage is that there is no control over the line
and grade and in case of obstructions like boulders, the pipe
may be deflected. Then work should be stopped immediately.
For small diameter pipelines, the method is economical, but for
large diameter pipes, the equipment cost is high.
MOLING:
Moling is a method, which forms the borehole by compressing
the earth that immediately surrounds the compacting device
which is an underground piercing (mole) is propelled by a
power source. The tool is streamlined into bullet or
shape. The method is restricted to relatively small diameter
lines in compressible soil conditions.
Compressed air or hydraulic fluid, transmitted to
the toot through the flexible hoses, imparts energy at a blow
frequency of 100 to 600 strokes per minute to a reciprocating
piston located inside the nose of the tool. This action results in
the tool propelling itself through the ground. It is applicable in
22)

23. most ground conditions from loose sand to firm clay. The
method required the use of boring and receiving pit. After the
operation the unit can be backed out of the borehole. The tool
is removed and the cable is attached to the air hose and pulled
back through the borehole. In the case of rigid pipe, it can
simply be pushed through the open borehole. Any type of pipe
or cable can be installed by the method.
Moling Equipment
Pipe size is generally limited to 6 inches or less. However,
modern techniques in mole manufacturing have increased the
ability to make bores of large sizes. Even though 200 feet (60
meter) bores have been successfully made by this method, the
span lengths were limited to 60 feet (18 meter) with 40 feet
23)

24. being optimum. Again span lengths have increased with
modern advances in mole design.
ADVANTAGES:
It is a rapid, economic, and effective method of installing small
diameter lines. Any type of utility line can be installed using the
method. The stability of the soil around the borehole is
increased due to compaction. The investment in equipment is
minimum.
DISADVANTAGES:
Compaction methods are limited in their length by reliability
because basic systems are unintelligent, unguided tools that
tend to bury themselves, surface in the middle road or damage
existing utility lines.
AUGER BORING:
The auger horizontal earth boring is a process of
simultaneously jacking casing through the earth while removing
the spoil inside the casing by means of a rotating flight auger.
The auger is a flighted tube having dual functions, firstly it has
couplings at each end that transmit torque to the cutting head
from the power source located in the bore pit and secondly, it
serves to transfer spoil back to the machine.
24)

25. Augur Blades
This method requires bore pit both at the entry and exit
points of the bore. The auger-boring machine consists of the
boring machine, casing pipe, cutting head and augers as the
major components. The power source creates the torque,
which rotates the auger, which in turn rotates the cutting head.
The cutting head cuts the soil and the soil is transported to the
machine through the casing by means of the auger, which acts
as a screw conveyor.
The pipe size that can be installed by this method ranges
from 4 inches (100mm) to over 60 inches (1500 mm). However,
the most common size range is 8 inches(200 mm) to 36
inches(900 mm) and the average bore length ranges between
25)

26. 53 meter and 68 meter, though with experience and the use of
latest techniques up to 180 meter of boring is possible using
auger boring.
ADVANTAGES:
The major advantage is that the casing is installed at the same
time as the borehole excavation takes place. This method can
be used in a wide variety of soil types.
DISADVANTAGES:
This method requires different sized cutting heads and auger
sizes or each casing diameter, which increases the investment
in equipment. The investment in bore, pit construction, and the
initial setup is also required. In case of soils containing large
boulders, this method cannot be used advantageously.
26)

27. NEED FOR TRENCHLESS
TECHNOLOGY
(1) The disadvantages and difficulties encountered in
conventional trenching methods have resulted in thinking of
the need for trenchless technology.
(2) The advantages of the no-dig technology are also
responsible for the need of this technology to be adopted in
mainly urban areas
OPEN TRENCH METHOD:
It is a traditional method of trenching for laying the utility lines
below the surface. In present days, there are many
disadvantages and difficulties in adopting this method, mainly in
urban areas. Those are described below:
1) As the open trench is going to create obstruction roads,
busy areas, diversions have to be provided before start of
any digging word.
2) As the obstruction is created, the traffic has to be rerouted
causing traffic jams.
27)

28. Original users of the road have to undergo hardships in the
form of additional mileage as well as time.
Many a time, while cutting deep trenches in congested areas
appear in the adjacent buildings.
Another difficulty, which is encountered very often is the
damage caused to other service lines or cables present
underground, providing temporary supports to these lines
during the construction is cumbersome and costly affair.
Trenches left open overnight should be fenced and barricaded.
Hand of mechanical signs should be used where necessary.
While cutting open trenches, trees, shrubs, gardens etc. may
have to be destroyed damaging the environment.
If any rehabilitation or renovation is required, the trenches once
cut and refilled should again be cut through out and refilled
causing difficulties to the public; that is, cutting and refilling is
required at frequent times
28

29. ADVANTAGES OF NO-DIG
TECHNOLOGY
 It reduces damages of valuable surface.
 It reduces the danger of improperly compacted
excavations.
 It saves resources.
 It is accident free.
 It avoids traffic jam.
 It makes the use of the line(track) of the old pipe possible.
 It saves underground space (pipe busting).
 It reduces the impact on the environment.
 It provides the hassle-free road surface.
 It is possible to lay service lines across railway track,
narrow lanes etc. When open trenching is impossible.
 Presence of a canal, pond, river etc. across the root poses
no problems to the trench less technology systems.
29)

30. UTILISATION OF RESEARCH
RESULTS
The use of Trenchless Technology for the installation of new, or
the replacement or refurbishment of existing buried utilities
have become well accepted over the past 25 years.
In this time many techniques have been developed including,
soil displacement moles, pipe bursting, ramming, loose and
tight fit insertion, directional drilling, pipeline relining and many
more.
Today the techniques have become readily accepted and are
often referred to as No-Dig or Limited Dig. They are now not
only associated with reduced disturbance to the surrounding
ground surface of a specific project, but are also seen as cost
saving, and environmentally friendly with benefits including;
reduced excavation size, lower infill and landfill requirements,
increased safety, less noise and traffic disruption and much
more.
30)

31. CONCLUSIONS
With all round developments in various fields like
petrochemicals where conveyance of gas, crude and refined
products over long distances is common, telecommunication
and power, water supply and sewerage etc. and mushrooming
growth of high- rise buildings in and in and around the cities is
becoming increasingly necessary that these lines are laid
underground leaving space above surface comparatively free.
i.e., Adoption of trench less technology is the only remedy.
Also if costs benefit analysis of the two systems (i.e. open
trenching methods and trenchelss technology methods) is
conducted, considering both direct and indirect costs, it will help
us make informed divisions on technology selection, under
different circumstances.
31)

32. REFERENCES
 Jagadish Chandra, “Trenchless Technology in India: Need
of the New Millennium.” Civil Engineering and
Construction Review October 2009- page 48
 Maninder Singh, “Techniques of Trenchless Technology
In Use In India.” Civil Engineering and Construction
Review October 2009- page 43
 Dr.Neeraja Lugani Sethi, “Pre- Requisites for Trenchless
Technology.” Civil Engineering and Construction Review
October 2009- page 21
 Sarkar A.K, “Trenchless Technology and INDSTT In
India.” Civil Engineering and Construction Review October
2009- page 13
 The Construction Journal of India November 2009-
page21
32)