This document discusses trenchless technology methods for installing and rehabilitating underground infrastructure with minimal surface disruption. It describes various trenchless methods for new installation like microtunneling, horizontal directional drilling, and short drive systems. Rehabilitation methods discussed include pipe bursting, pipe eating, cured-in-place lining, slip lining, and localized spot repairs using materials like coatings, cement mortar, resins, and grout. The document outlines advantages such as speed, minimal environmental impact, and ability to install pipes under obstacles like rivers. Trenchless technology is gaining popularity in India for projects installing pipes below rivers and urgent sewer repairs.

1. TRENCHLESS TECHNOLOGY
PRESENTED BY
REMYA RAJEEV

2. CONTENTS
 INTRODUCTION
 TRENCHLESS TECHNOLOGY METHODS
 REHABILITATION
 ADVANTAGES
 DISADVANTAGES
 CONCLUSION

3. INTRODUCTION
 Trenchless technology can be defined as “a family of
methods, materials and equipment capable of being used for
the installation of new or replacement or rehabilitation of
existing underground infrastructure with minimal disruption to
surface traffic, business and other activities”
 The difference between trenchless and other subsurface
construction techniques depend on the size of passage under
construction.
 If a subsurface construction does not permit human entry, it
can be termed “trenchless”.

4. TRENCHLESS TECHNOLOGY
METHODS
 NEW INSTALLATION
 REHABILITATION AND RENOVATION

5. NEW INSTALLATION
 MICROTUNNELING
 HORIZONTAL DIRECTIONAL DRILLING
 SHORT DRIVE SYSTEM
 GUIDED DRILLING

6. MICRO TUNNELING
 Only excavation required is for drive and reception shafts.
 Can be used in almost all types of ground conditions.
 First step, soil is converted in to slurry using water or
betonies.
 Temporary steel tubes are jacked in and removed at next
manhole position.
 Only indication on the surface is the presence of a control
container with a hoist for lowering pipes in to the drive
shafts.
 Noise levels and traffic disruption minimized.

8. HORIZONTAL DIRECTIONAL DRILLING
 These are nowadays widely used for installing pressure pipes under major
obstacles such a motor way intersections, large rivers and airports
runways.
 The first stage consists of drilling a small diameter pilot hole along the
desired centre line of a proposed line.
 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.
 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.
 Before the start of back reaming the pipeline has to be positioned on
rollers in line with the hole to minimize any axial load on the line.

10. ADVANTAGES
 Speed of installation combined with the minimum
environmental and social impact.
 Method involves minimum surface damage
 Save a lot of time and expenses.
 Great importance in congested urban areas where the numbers
of underground utilities are high often very little space is
available.
 River crossings, the effect of buoyancy and danger of river bed
erosion are eliminated as the utility can be installed.

11. DISADVANTAGES
 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 method.

12. SHORT DRIVE SYSTEMS
 AUGER BORING
 RODPUSHING
 PIPE RAMMING & THRUST BORING
 GUIDED DRILLING

13. AUGER BORING
 Utilizes rotating head to excavate
 Head is recovered at an exit pit for the adjacent length of the
pipe.
 Used in the range of 100-1000mm diameter
 Requires bore pits at both entry and exit points.
 Pipe size from 100-1500 mm and avg bore length btwn 53-68
m
 Major advantage is casing is installed at same time as bore
hole excavation.
 Requires different sized cutting heads and auger sizes.
 Difficult to use in soils containing large boulders.

15. AUGER BORING

16. IMPACTMOLING
 Pipe size is generally limited to 6 inches or less.
 The span lengths were limited to 60 feet (18
meter) with 40 feet being optimum.
 Any type of pipe or cable can be installed.
 Applicable in most ground conditions.

17. ADVANTAGES
 Rapid, economical and effective method for
installing small diameter lines
 Any type of utility line can be installed using this
method.
 Stability of soil around the borehole is increased
due to compaction
 Investment in equipment is minimum.

18. DISADVANTAGES
 Compaction methods are limited in length by
reliability because basic systems are unintelligent
 Unguided tools tend to bury themselves, surfaces
in the middle of road or damage existing utility
lines.

20. ROD PUSHING
A bore of diameter 50 mm is formed by
displacement.
 Rod is advanced by a straight hydraulic push
and pilot hole may be back reamed to
required size.
 Used for installation of pipes and conduits up
to 15mm dia over lengths of 30-40 mm

21. PIPE RAMMING & THRUST BORING
 Suitable for most soil types except solid rock
formations.
 Cost saving alternative to open trenching,
pipe jacking methods.
 Pipes up to 2000mm dia can be laid using
this technique.

22. GUIDED DRILLING
 Itemploys an excavation or soil displacement
with compact light weight rig for rapid
mobilization.

23. REHABILITATION & RENOVATION

24. PIPE BURSTING
 PNEUMATIC PIPE BURSTING
 STATIC PIPE BURSTING

25. PNEUMATIC PIPE BURSTING
 Air powered hammer mounted inside bursting head.
 Constant tension winch designed to facilitate extraction of
burst head.
 Excavation cost reduced.
 Bursting head bursts damaged pipeline and new pipe is
pulled in.
 Lubricants used for larger and longer bursts.
 HDPE pipe is used.

27. STATIC PIPE BURSTING
 Preferable in clayey soils .
 Existing pipelines can be replaced without opening
up ground.
 Mole is used as bursting head.
 Small power source is used to drive mole .

28. PIPE EATING
 Based on micro tunneling.
 Defective pipe excavated together with surrounding
ground.
 Consists of micro tunneling shield.
 Shield has larger diameter than existing pipe.
 Pipe fragment can be removed by 2 methods
1. Vacuum excavation
2. Slurry pumping

29. Contd..
 Pipe eating shield is pushed forward using
hydraulic jacks.
 Replacement pipes are connected to the
back of tunneling shield.
 This technique can be used to replace
clayware,concrete,asbestos pipe etc.

30. RELINING THE EXISTING PIPES
 CURED-IN-PLACE LINING
 CLOSE-FIT LINING
 SLIP- LINING
 SPRAY LINING

31. CURED-IN-PLACE LINING
 Fabric impregnated with polyester or epoxy resin is
inserted in to defective pipe & inflated against pipe
wall.
 Cured by hot water, steam or UV light.
 The lining adjusts to variations in pipe size.
 Used for the rehabilitation of gravity sewers etc.
 Usually results in no loss of capacity.

32. CLOSE-FIT LININGS
 It is deformed through a swage a metal dye) or
manufactured in folded state.
 Spirally wound liners are a form of close-fit.
 Useful for emergency repairs and for strengthening
weak pipes.

33. SLIP-LINING
 Involves putting a pipe within a pipe and grouting the
resulting annulus between the pipes.
 Causes reduction in capacity.
 Modifications are introduced to reduce thickness of liner
and size of annulus.

34. SPRAY LINING
 Cement or resin is used.
 Cost effective.
 Ease of transport
 Mobilization of equipment.

35. RELINING PIPES

36. LOCALIZED REPAIR
 COATINGS
 CEMENT MORTAR
 REINFORCED GUNITE
 RESIN
 GROUT

37. COATINGS
 Used to repair cracks
 To protect from corrosion ,mechanical abrasion.
 Manual coating possible for pipes with a minimum of 1.21
m diameter.
 No extra work or equipment needed.

39. CEMENT MORTAR
 Applied to concrete, steel or iron pipes.
 Service life extended up to 50 yrs.
 Made of 1 part sulphate resistant cement to 2
parts sand.
 Cannot be applied in pipe networks with many
bends, or in very cold regions.

40. REINFORCED GUNITE
 Also referred as “SHOTCRETE”
 Mixture of cement, sand and water.
 Steel reinforcing mesh attached inside pipe.
 Improves structural integrity of system.
 Can be used on varying cross-sectional profiles.
 It reduces internal diameter of original pipe.
 Reduces coefficient of friction.
 Application restricted to pipes of dia greater than 4ft.

41. RESINS
 Coating are made of polyurethane, phenol epoxy or poly
urea.
 Can solve problems of corrosion and erosion.
 Can be applied to steel or concrete pipes.
 Excellent adhesion and impermeability.

42. GROUT
 Grout is a variety of materials used to fill voids, stabilize
soil, hold bricks in place, coat cement & prevent
infiltration.
 Used here to seal the joints between segmented concrete
pipes.
 Used to seal off ground water infiltration in non pressure
pipelines.
 Adapts well to irregular surface.

43. LIMITATION & ADVANTAGES OF
GROUT
Limitations Advantages
Not a structural repair Stops groundwater from leaking in
Requires highly skilled operators Stabilizes soil
Difficult to seal actively infiltrating Fills void around pipe
joints
Packer will not seal properly in badly Is a long-term, inexpensive trench less
corroded pipe technology
Not for small- or large-diameter pipe Well suited to 10- to 15-in. pipe
Can make small cracks bigger
Pipe must be thoroughly cleaned and in good condition (no protruding taps or
broken sections)

44. TRENCHLESS TECHNOLOGY IN
INDIA
 Brihan Mumbai Municipal Corporation for the construction of 3m dia.
Tunnel by micro tunneling.
 MTNL in Delhi, kolkata installing large telephone cables by T.T.in Delhi 185
k.m line is made by this.
 Pipe line laying below river bed is impossible by open trench method, pipe
line laying below Hoogly river by this technique is sufficient to say its
importance
 In Varanasi(u.p) an urgent repair for brick sewers is successfully done by this
 In kolkata 700m length and .762 dia. Iron pipe was repaired which started
leakage.
 Laying of 18’ dia. Pipe of HBJ across yamuna river is accomplished by this
technique
 1719m gas pipeline was laid 35mbelow gautam-godavari river in 1994
 3 underground crossing of 24’ dia. And 350 long pipes were completed by
Indian
 Oil Corporation for panipat refinery.

45. NEED FOR TRENCHLESS
TECHNOLOGY
 The disadvantages and difficulties encountered in
conventional trenching methods have resulted in
thinking of the need for trench less technology.
 The advantages of the no-dig technology are also
responsible for the need of this technology to be
adopted in mainly urban areas

46. OPEN TRENCH METHOD
– As the open trench is going to create obstruction roads, busy
areas, diversions have to be provided before start of any digging
word.
– As the obstruction is created, the traffic has to be rerouted
causing traffic jams.
– 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.

47. CONTD..
– 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

48. 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.
 Without disturbing the traffic and life on the surface, the lines can be laid
below ground in a much shorter time by using this technology.
 For replacement, repair and rehabilitation of old water and sewer lines in
cities, it is very helpful to use trench less technology without disturbing the
normal life on the surface.

49. CONCLUSION
Planners need to understand the opportunities that the alternative TT has to
offer. Designer must design with the knowledge that a wide range of TT and
techniques are already available with continuing economic advantages.
Likewise with trench less installation, refurbishment and rehabilitation
techniques, a wide range of social technical and economical advantages will
also be readily available. High level strategies within the utilities to utilize the
available technology must be encouraged. This implies developing an
understanding of the value of the application of technology and linking this
closely with asset management strategies already in place. Once there is
greater awareness of the impressive state of development that T.T industry
has achieved when advantage is taken of the range of technique equipment
and material that already exist and when the traffic authorities and utilities
recognize the need for and advantage of T.T then the true potential of no-dig
techniques will start to be realized.