21-05-2012, 05:00 PM
trenchless technology
Trenchless Technology.doc (Size: 909 KB / Downloads: 84)
INTRODUCTION
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 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 method is many times used without considering soil characteristics, overburden and the loads coming on the surface where the method is used. in case, the soil is sandy, water table is at shallow depth and heavy loads like that of urban traffic is expected, the depth of trenching has to be at a depth that the pressure of the load on the surface does not affect the bore else surface caving in cannot be ruled out. Therefore, sufficient precautions should be taken in loose and sandy soil strata, particularly near the ends from where the trenching is started or ended. Traditional open trench method seems ineffective for present requirement like under roads, railway tracks, highways, sewers, drains, cables etc.Without any disruption to traffic as it is not necessary to dig up or cut across the road. Other obstacles encountered in adopting these old methods are described as follows:
TRENCHLESS TECHNOLOGY METHODS
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) Microtunelling
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.
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 .
Microtunneling 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.
Trenchless Technology.doc (Size: 909 KB / Downloads: 84)
INTRODUCTION
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 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 method is many times used without considering soil characteristics, overburden and the loads coming on the surface where the method is used. in case, the soil is sandy, water table is at shallow depth and heavy loads like that of urban traffic is expected, the depth of trenching has to be at a depth that the pressure of the load on the surface does not affect the bore else surface caving in cannot be ruled out. Therefore, sufficient precautions should be taken in loose and sandy soil strata, particularly near the ends from where the trenching is started or ended. Traditional open trench method seems ineffective for present requirement like under roads, railway tracks, highways, sewers, drains, cables etc.Without any disruption to traffic as it is not necessary to dig up or cut across the road. Other obstacles encountered in adopting these old methods are described as follows:
TRENCHLESS TECHNOLOGY METHODS
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) Microtunelling
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.
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 .
Microtunneling 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.