Trenchless
Encyclopedia
Trenchless technology is a type of subsurface construction work that requires few trenches or no continuous trenches. It is a rapidly growing sector of the construction
and civil engineering
industry. It 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."
, microtunneling
(MTM), horizontal directional drilling
(HDD) also known as directional boring
, pipe ramming
(PR), pipe Jacking (PJ), moling
, horizontal auger boring
(HAB) and other methods for the installation of pipelines and cables below the ground with minimal excavation. Large diameter tunnel
s such as those constructed by a tunnel boring machine
(TBM
), and drill-and-blast techniques are larger versions of subsurface construction. The difference between trenchless and other subsurface construction techniques depends upon the size of the passage under construction.
The method requires considering soil characteristics and the loads applied to the surface. In cases where the soil is sandy, the water table is at shallow depth, or heavy loads like that of urban traffic are expected, the depth of excavation has to be at a depth such that the pressure of the load on the surface does not affect the bore, otherwise there is danger of surface caving in.
Trenchless rehabilitation includes such construction methods as sliplining
, thermoformed pipe, pipe bursting, shotcrete
, gunite, cured-in-place pipe
(CIPP), grout-in-place pipe, mechanical spot repair, and other methods for the repair, rehabilitation, or replacement of existing buried pipes and structures without excavation, or at least with minimal excavation. Mechanical Spot Repair is applied where damaged pipelines require the re-instatement of structural integrity. Sliplining, CIPP, and thermoformed pipe lining involve pulling or inverting a new liner into an existing pipe, then applying heat and/or pressure to force the liner to expand to fill the pipe. CIPP technologies combine a carrier (felt or fibreglass) impregnated with heat, ultraviolet light, or ambient curable resin to form a "pipe within a pipe". Pipe bursting fractures a pipe from the inside and forces the fragments outwards while a new pipe is drawn in to replace the old. The other methods are primarily for fixing spot leaks.
Trenchless rehabilitation methods are generally more cost-effective than traditional exhume (dig) and replace methods.
(NASSCO) was established in 1976 and is the oldest such association with a trenchless focus. The North American Society for Trenchless Technology (NASTT) was established in 1990. The Indian Society for Trenchless Technology or IndSTT is the apex organization to promote Trenchless Technology in South Asia. It was established in 1995 with its head office at New Delhi. The International Society for Trenchless Technology
, established in 1986, has 25 active national trenchless technology societies associated with it. Several organizations bring out Technical Journals for sensitizing the readers about such techniques. No Dig India is the official Journal of IndSTT.
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...
and civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
industry. It 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."
Trenchless Construction
Trenchless construction includes such construction methods as tunnelingTunneling
Tunneling may refer to:* Digging tunnels * Quantum tunneling, the quantum-mechanical effect where a particle crosses through a classically-forbidden potential energy barrier...
, microtunneling
Microtunneling
As the name implies, microtunneling is a digging technique used to construct small tunnels. These small diameter tunnels make it impossible to have an operator in the machine itself. Instead, the microtunnel boring machine must be operated remotely.Microtunnel boring machines are very similar to...
(MTM), horizontal directional drilling
Directional drilling
Directional drilling is the practice of drilling non-vertical wells. It can be broken down into three main groups: Oilfield Directional Drilling, Utility Installation Directional Drilling Directional drilling (or slant drilling) is the practice of drilling non-vertical wells. It can be broken down...
(HDD) also known as directional boring
Directional boring
Directional boring, commonly called horizontal directional drilling or HDD, is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface launched drilling rig, with minimal impact on the surrounding area....
, pipe ramming
Pipe ramming
Pipe ramming is a trenchless method for installation of steel pipes and casings. Distances up to 30m up long and up to 1,500mm in diameter are feasible, although the method can be used for much longer and larger installations...
(PR), pipe Jacking (PJ), moling
Moling
In the construction industry, moling is a trenchless method used to lay pipes. During the moling process, a pneumatically-driven machine known as a mole forces its way through the soil along the desired path of the pipe...
, horizontal auger boring
Boring
Boring often refers to anything that causes boredom.Boring may also refer to:Making holes*Boring , the drilling of holes or tunnels in the earth**Tunnel boring machine machine used in boring tunnels or shafts...
(HAB) and other methods for the installation of pipelines and cables below the ground with minimal excavation. Large diameter tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...
s such as those constructed by a tunnel boring machine
Tunnel boring machine
A tunnel boring machine also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They can bore through anything from hard rock to sand. Tunnel diameters can range from a metre to almost 16 metres to date...
(TBM
TBM
TBM may refer to:* Socata TBM, a single engine turboprop aircraft* Tactical ballistic missile* TBM Avenger, the designation given to Grumman TBF Avenger torpedo bomber airframes produced by General Motors....
), and drill-and-blast techniques are larger versions of subsurface construction. The difference between trenchless and other subsurface construction techniques depends upon the size of the passage under construction.
The method requires considering soil characteristics and the loads applied to the surface. In cases where the soil is sandy, the water table is at shallow depth, or heavy loads like that of urban traffic are expected, the depth of excavation has to be at a depth such that the pressure of the load on the surface does not affect the bore, otherwise there is danger of surface caving in.
Trenchless Rehabilitation
Sliplining
Sliplining is one of the oldest methods for trenchless rehabilitation of existing pipelines. Sliplining is used to repair leaks or restore structural stability to an existing pipeline. Sliplining is completed by installing a smaller, "carrier pipe" into a larger "host pipe", grouting the annular...
, thermoformed pipe, pipe bursting, shotcrete
Shotcrete
Shotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....
, gunite, cured-in-place pipe
Cured-in-place pipe
A cured-in-place pipe is one of several trenchless rehabilitation methods used to repair existing pipelines. CIPP is a jointless, seamless, pipe-within-a-pipe with the capability to rehabilitate pipes ranging in diameter from 0.1–2.8 meter...
(CIPP), grout-in-place pipe, mechanical spot repair, and other methods for the repair, rehabilitation, or replacement of existing buried pipes and structures without excavation, or at least with minimal excavation. Mechanical Spot Repair is applied where damaged pipelines require the re-instatement of structural integrity. Sliplining, CIPP, and thermoformed pipe lining involve pulling or inverting a new liner into an existing pipe, then applying heat and/or pressure to force the liner to expand to fill the pipe. CIPP technologies combine a carrier (felt or fibreglass) impregnated with heat, ultraviolet light, or ambient curable resin to form a "pipe within a pipe". Pipe bursting fractures a pipe from the inside and forces the fragments outwards while a new pipe is drawn in to replace the old. The other methods are primarily for fixing spot leaks.
Trenchless rehabilitation methods are generally more cost-effective than traditional exhume (dig) and replace methods.
Trade Associations
The trenchless technology industry is represented by several industry associations in addition to standing committees within almost every water and sewer related industry association. The National Association of Sewer Service CompaniesNational Association of Sewer Service Companies
The National Association of Sewer Service Companies or NASSCO is a North American trade organization, established in 1976 to "improve the success rate of everyone involved in the pipeline rehabilitation industry through education, technical resources, and industry advocacy"...
(NASSCO) was established in 1976 and is the oldest such association with a trenchless focus. The North American Society for Trenchless Technology (NASTT) was established in 1990. The Indian Society for Trenchless Technology or IndSTT is the apex organization to promote Trenchless Technology in South Asia. It was established in 1995 with its head office at New Delhi. The International Society for Trenchless Technology
International Society for Trenchless Technology
The International Society for Trenchless Technology or ISTT is an organization founded in 1986 to promote and advance Trenchless Technology....
, established in 1986, has 25 active national trenchless technology societies associated with it. Several organizations bring out Technical Journals for sensitizing the readers about such techniques. No Dig India is the official Journal of IndSTT.
External links
- Trenchless Technology, what is it anyway?
- Indian Society for Trenchless Technology
- United Kingdom Society for Trenchless Technology
- Center for Underground Infrastructure Research and Education CUIRE
- China Hong Kong Society of Trenchless Technology CHKSTT
- National Association of Sewer Service Companies