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Search the ASTT technical archive.
Papers, case studies, standards and webinars covering trenchless methods across Australia and New Zealand.
459 results (298 ASTT documents, 161 ISTT technique descriptions) · showing 385–408
Non-structural (Sealing)
In this category of repair, the target for the rehabilitation of the host pipe is to deal with localized leakage either into or out of a pipe rather than an improvement in the structural condition of the pipe. When a pipe is basically in sound overall condition, this approach can be cost effective in addressing…
ISTT
Nozzle Camera
A nozzle camera is a camera placed at the front of a rod or cable such that is can be pushed through small pipes or tubes to provide images of the interior of the pipe/tube. Such cameras have a wide range of application in many industries. Their most common application in trenchless technology is the inspection of…
ISTT
Nuclear Methods
As the name implies, nuclear methods use radiation sources to gather information about the properties of the ground surrounding a borehole in which the scanning device is inserted. Depending on the type of radiation used, information about changes in soil density or the presence of voids and changes in groundwater…
ISTT
Operational Performance Assessment
Obviously, the operational performance of a system is strongly connected to the physical condition of the system, however, this category of assessment is aimed at how well the system is functioning at the current time and the operational condition of its many valves, safety equipment and appurtenances. Key areas of…
ISTT
Other
Particularly in person-entry-scale pipe jacking, a variety of other face support measures (as are used in conventional tunnelling) are possible. These methods include mechanical breasting plates, sand shelves and partially closed faces. Spoil Handling Spoil handling is an important method characteristic in…
ISTT
Other Close-fit Lining
In this category, various other types of close-fit linings are described. They may achieve their close-fit status by temporarily deforming the lining pipe while it is being inserted or by creating the lining inside the existing pipe in such a way that it conforms closely to the interior of the host pipe. In some…
ISTT
Other Methods
There are a variety of other forms of surface-based investigation for locating buried objects. The simplest of these being a metal detector and one of the more sophisticated being a micro-gravity survey instrument.
ISTT
Other Technologies
For further information about the wide range of tunnelling technologies and their application, please consult the many books available on tunnel technology and/or visit the website of the International Tunnelling Association www.ita-aites.org .
ISTT
Overflow Detection
Overflows from sewer systems may occur at designed overflow points in older combined sewer systems or at unplanned locations due to excessive flow during rain events. Monitoring the extent and locations of overflows is important both in tracking pollution releases and in understanding the level and distribution of…
ISTT
Panel Lining
(Other names for longitudinally short liners include sectional lining, discrete lining, segmental lining and short element lining.) This renovation option applies essentially to person-entry pipes, tunnels, manholes, chambers, etc. In this technique, pre-formed panels are fabricated to fit closely to the interior…
ISTT
Person-Entry
Person-entry scale pipe jacking provides more options to address problems that may occur during the pipe jacking process. Access to the face is possible to inspect/remove obstructions, change cutterheads or maintain equipment.
ISTT
Pilot Tube Assist Technologies
A variety of hybrid methods incorporate the use of a pilot tube to establish an accurate alignment between two shafts or the two sides of a crossing. The pilot tube typically is a small steel tube of around 100 mm diameter. In its basic use, it is thrust (with or without rotation) in a straight line through…
ISTT
Pipe Bursting
Pipe bursting is a trenchless method used to replace existing pipelines in the same alignment without physically removing the existing pipeline. By using the existing alignment to replace a pipe, the need to secure additional right-of-way to install the replacement pipe can be avoided. Bursting can be used to…
ISTT
Pipe Eating
Pipe eating uses a microtunneling type machine to crush and “excavate” the existing pipe together with sufficient surrounding ground to accommodate the new pipe which is simultaneously jacked in behind. The interior volume of the existing pipe can be grouted to provide a more uniform face condition for…
ISTT
Pipe Extraction
Pipe extraction is a trenchless method, which can remove an existing pipe for disposal and replace it with a new pipe - typically a high density polyethylene (HDPE) or polyethylene (PE) pipe. There are several systems that have been developed to remove existing service lines while at the same time replacing them with…
ISTT
Pipe Jacking / Microtunnelling
Pipe jacking is a tunneling method where a pipe being installed is used also as ground support during the tunneling operation. In this method, sections of pipe are lowered into the launching shaft and are thrust forward using jacks at the launching shaft as the tunnel advances. At the excavation face, a variety of…
ISTT
Pipe Ramming
Pipe ramming is a trenchless method for installing steel casing pipe under roads, railroads and other structures. The casing is installed open ended, which allows the soil to enter the casing. Containing the soil in the casing minimizes the potential for surface settlement, which allows the casing to be installed at…
ISTT
Pipe Reaming
Pipe reaming is a trenchless method that removes the host pipe while at the same time installing a new replacement pipe. Pipe reaming can be used to replace various types of existing pipes and is particularly well suited for replacing and upsizing pipes in stiff soils and rock where pipe bursting may not be an option.…
ISTT
Pipe Splitting
Pipe splitting is a trenchless method used to replace existing pipelines in the same alignment without physically removing the existing pipeline. Splitting the existing pipe and hence using the existing alignment to replace a pipe avoids the need to secure additional right-of-way to install the replacement pipe.…
ISTT
Pneumatic / Hydraulic Hammer
A pneumatic hammer device was the original pipe bursting device used in the UK for replacing gas mains. The hammering of the conical head within the end of the pipe being burst creates the radial expansion forces to fracture the existing pipe. A cable under tension is used to advance the bursting head and keep it in…
ISTT
Polymeric Coating / Lining
Polymeric (thermosetting) coatings and liners (notably epoxy, polyurethane (PU) and polyurea resins) are used to provide corrosion protection in small diameter metallic pipelines and corrosion protection and semi-structural rehabilitation and leak protection in man-entry pipes, tunnels and manholes. As with cement…
ISTT
Potholing
Sometimes it may be effective to perform potholing techniques to locate or inspect an underground service. When a utility is exposed by potholing, precise location information can be collected for that point along the utility's length. Such information can be rapidly collected using survey-grade GPS systems. Some…
ISTT
Potholing for Local Repair
Where suitable internal repairs are not possible, it may be necessary to access the pipe from the surface to complete a repair, install a valve, etc., e.g. in the case for water or gas mains providing service to property owners along a public right-of-way. Potholing / Keyholing Potholing or keyholing is a method of…
ISTT
Potholing/Keyholing, Coring, Vacuum Excavation
Potholing / Keyholing Potholing or keyholing is a method of accessing underground infrastructure with minimal excavation, disruption of services, traffic and pedestrians, and reinstatement. The small, narrow, vertical excavations are precisely controlled. It usually involves coring the existing surface, excavating…
ISTT