TRENCHLESS TECHNOLOGY METHODS
TECHNIQUES OF TRENCIILESS TECHNOLOGY
NEED FOR TRENCILESS TECHNOLOGY
Trench less technology is the science of
installing, repairing and renewing
underground pipes, ducts and cables using
techniques which minimize or eliminate the
need for excavation. Trench less technology
is basically making a tunnel below the
surface and staling service lines like water or
gas pipes, electric or telecommunication
cables etc, with out any disruption to the
Trenchless technology methods
system have been categorized in to
1) New installation
2) Rehabilitation and Renovation
Methods for installation of a new pipeline
or duct, including dealing with service
2) Horizontal directional drilling
Methods including are:
1) Pipe bursting
2) Pipe eating
Surveys and site investigations are essential to the
success and efficiency of trench less installations and
(a) The survey results help to determine the most
(b) The investigations methods include geophysical
surveys, boring and sampling, measurement of
ground water table, test pits and trenches,
penetration tests, examinations and investigations of
TECHNIQUES OF TRENCHLESS
TECHNOLOGY IN INDIA
Directional drilling involves steerable tunnelling
systems for both small and diameter lines. 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 major advantage is the speed of installation
combined with the minimum environmental and social
Long and complicated crossings can be accomplished
with a great degree of accuracy.
Another advantage is that sufficient depth can be
accomplished to avoid other utilities.
Limitation of access and reception pits is another
Special equipment and very high degree of
operation skill is required.
As the cost of the equipment and the operation
are high, bore length should be sufficient in
order for it to be economical.
Mainly steel pipe is being installed by the
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. 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.
The pipe ramming is an effective method for
installing medium size pipes.
The method is economic since the equipment cost
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
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
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 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.
It is a rapid, economic, and effective method of
installing small diameter lines.
Any type of utility line can be installed using the
The stability of the soil around the borehole is
increased due to compaction.
The investment in equipment is minimum.
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.
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.
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.
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.
NEED FOR TRENCHLESS
(1) The disadvantages and difficulties
encountered in conventional trenching methods
have resulted in thinking of the need for
(2) The advantages of the no-dig technology are
also responsible for the need of this technology
to be adopted in mainly urban areas
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.
Also if costs benefit analysis of the two systems is
conducted, considering both direct and indirect
costs, it will help us make informed divisions on
technology selection, under different
1) Jagadish Chandra, Trenchless Technology in
India: Need of the New Millennium. Civil
Engineering and Construction Review October
2000- page 48
2) Maninder Singh, Techniques of Trenchless
Technology In Use In India. Civil Engineering and
Construction Review October 200- page 43
3) Dr.Neeraja Lugani Sethi, Pre- Requisites for
Trenchless Technology. Civil Engineering and
Construction Review October 2000- page 21