A PRESENTATIONON

“TRENCHLESS TECHNOLOGY”

Presented by

S.Mounika N.V.Prasad(132U5A0112) (122U1A0157)IIIyr-Civil IIIyr-Civil

DEPARTMENT OF CIVIL ENGINEERINGGEETHANJALI INSTITUTE OF SCIENCE & TECHNOLOGY(Affliated to JNTU Ananthapur, Approved by AICTE)

CONTENTS:

INTRODUCTION

NEED FOR TRENCHLESS TECHNOLOGY

TRENCHLESS METHODS

TECHNIQUES OF TRENCH LESS TECHNOLOGY

CONCLUSION

INTRODUCTION:

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 installing services lines like water or gas pipes, electric or telecommunication cables etc with out 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

NEED FOR TRENCHLESS TECHNOLGY :Various problems that arise due open trenching methods can be demolished by this trenchless methods

ADVANTAGES OF TRENCHLESS TECHNOLOGY:1. It reduces damages of valuable surface.2.It reduces the danger of improperly compacted excavations.3.It saves resources.4.It is accident free.5.It avoids traffic jam.6.It makes the use of the line(track) of the old pipe possible.7.It saves underground space (pipe bursting).

8.It reduces the impact on the environment.9.It provides the hassle-free road surface.10.It is possible to lay service lines across railway track, narrow lanes etc. When open trenching is impossible.11.Presence of a canal, pond, river etc. across the root poses no problems to the trench less technology systems.12 .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.13.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.

DISADVANTAGES OF OPEN TRENCHING METHODS:

1.As the open trench is going to create obstruction roads, busy areas, diversions have to be provided before start of any digging work.

2.As the obstruction is created, the traffic has to be rerouted causing traffic jams.

3.Many a time, while cutting deep trenches in congested areas appear in the adjacent buildings.

4.Another difficulty, which is encountered very often is the damage caused to other service lines or cables present underground.

5.While cutting open trenches, trees, shrubs, gardens etc. may have to be destroyed damaging the environment.

Hence all the difficulties can be minimized using this trenchless technology techniques

TRENCHLESS METHODS:

Various trenchless methods are basically classified into following two classifications

1.NEW INSTALLATION2.REHABILITATION & RENOVATION

NEW INSTALLATION:

Methods for the installation of a new pipeline or duct, including dealing with service connections are :

1.Microtunnelling2.Horizontal directional drilling3.Short drive systems

MICROTUNELLING:Micro tunneling is a term which is used to describe remotely controlled mechanical tunneling systems where the soil is removed from the cutting head with in the new pipe line which is advanced by pipe jacking.

 

The only excavating required from the service is for drive and receptions shafts. Soil 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 .

 Microtunneling is used extensively for sewerage work where surface disruption has to be minimized

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. In microtunnelling, the only indication on the surface is the presence of a control container with a hoist for lowering pipes into the drive shafts. Noise levels and traffic disruption are minimised

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.

1. 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

2. During the drilling operation a 125mm diameter washover pipe is drilled over the pilot string and following some 100mm behind the head.

3. 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

4. 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.

SHORT DRIVE SYSTEMS:Auger boring: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

 

Impact moling:In this 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: Rod Pushing 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

Hence the above are the various new installation methods

that are generally adopted.

REHABILITATION & RENOVATION: Methods including are:

1.Pipe bursting2.Pipe eating3.Relining the existing pipes4.Localized repair

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.

Pipe eating:1.Pipe eating is an online micro tunneled replacement technique. 2.In this method the existing defective pipeline is crushed and removed through the new pipeline.3. Lateral connections must be disconnected in advance and may be replaced by rider sewers or reconnected by angled drilling.

pipe eatingRelining the existing pipe:

This method requires access, usually by manholes, at both ends of pipe. A flexible liner is placed into the defective pipe and with the use of water under pressure finds its own way and 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 inexpensive method of rehabilition of existing pipes

CONCLUSION:By adopting this technology we can successfully

implement pipes under the surface with out making any disruptions to the environment and public.

This enables us to retain our available resources. There by keeping the earth unexcavated

THANK YOU