07-02-2010, 07:07 PM
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TRENCHLESS TECHNOLOGY
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INTROD[/b]UCTION
TT techniques include methods of pipeline & utility installations with minimum amount
of surface excavation
TT techniques are mainly divided into two main areas: TRENCHLESS CONSTRUCTION
METHODS(TCM) and TRENCHLESS RENEWAL METHODS(TRM)
TCM includes all methods for new utility & pipeline installations
TRM includes all methods of renewing, rehabilitating, or renovating an existing old
or host pipeline or utility system
Trenchless construction and renewal project is site specific & successful completion
of it is dependent on factors such as accuracy, maximum installation length, diameter
range, & type of application
CONSTRENCHLESS TRUCTION METHODS
Divided into two major categories:
- HORIZONTAL EARTH BORING
- PIPE JACKING / UTILITY TUNNELING
AUGER BORING
Used for installation of steel pipes and casings, especially under railways & road
embankments
Very economical
It reduces damage to pavements and disruption to traffic, hence reduces social costs
associated with pipeline installations
MOLING
Used for laying water pipes
During moling process, a pneumatically driven machine known as a mole forces its way
through the soil along the desired path of the pipe
Mole is a steel cylinder about 60cm long and 6cm in diameter, works as a pneumatic
cylinder with pulsed compressed air causing the head of the mole to repeatedly hammer
against the soil in front of the mole
PIPE RAMMING
Used for installation of steel pipes and casings over distances usually upto 30m long
and upto 1.5m in dia
It is also used for shallow installations under railway lines and roads
It can be applied for horizontal as well as vertical installations
Method is pneumatic
WATER JETTING
Method is simple
It uses high speed jet of water to liquefy and remove soil
Special nozzle is attached to the end of a solid rod & extended into the bore hole
Disadvantages:-
- poor control of overcut
- disposal of large quantities of water and
muck
- possibility of ground settlement
MICROTUNNELING
Used to construct small tunnels for laying gravity pipe lines
Microtunnel boring machines are operated remotely
Operator controls the machine from a control room on the surface of ground
Most machines also have video cameras set up to give more information
BENEFITS OF TRENCHLESS TECHNOLOGY
Excavation is not necessary between access points
Require less space underground, minimizing chances of interfering with existing
utilities or abandoned pipes
Are generally quiet and nondisruptive
Require less exposed working area & therefore are safer for both workers & the
community