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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 313–336
CIPP Patch Repair
(Also known as CIPP Spot Repair, Part Liner, Patch Liner and Short Liner.) This uses Cured-in-Place-Pipe (CIPP) technology to create a short section of liner to patch a localized defect or joint in a length of pipe For the repair of a mainline pipe joint or defect, a pull-in-place CIPP section is used to patch a short…
ISTT
Close-fit Lining
This category of renovation covers pipe lining systems that install a new pipe lining within the existing pipe in a manner that provides a tight or reasonably tight fit to the inner surface of the existing pipe. This is important in maintaining the maximum remaining pipe cross-section after the renovation and also in…
ISTT
Composition
The most common resin used today in CIPP is polyester resin, normally an ISO-NPG resin. It has excellent properties for many applications and is economical, but other resins are used for specific applications. In particular, vinyl ester resins may be used for better resistance to chemical attack and epoxy resins for…
ISTT
Continuous Pipe
Polyethylene (HDPE and PE) and polyvinyl chloride (PVC) pipes are most commonly used for continuous slip lining of circular, non-person entry pipes. The new pipe is laid out above ground and pulled through an excavated pit into the host pipe. The new pipe is winched through the host pipe to an exit pit or manhole. In…
ISTT
Conventional Tunneling
Conventional bored tunneling (but not cut-and-cover tunneling) is a “trenchless” technology. The differences in trenchless and tunnelling methods used are primarily influenced by the scale of the installations – with conventional tunneling often dealing with large diameter tunneling and large urban…
ISTT
Conveyor
Conveyor belt spoil removal systems are possible in person-entry tunnel diameters. They may be used with open face tunnelling systems or with an earth-pressure balance (EPB) system.
ISTT
Crawler Platform
Crawler platforms (especially for CCTV systems) are widely used for inspection of mainline piping systems. They may also provide the platform for other types of sensing and survey systems.
ISTT
Cured-in-Place Pipe (CIPP)
Cured in Place Pipe (CIPP) can be used to rehabilitate gravity sanitary sewers, storm drains and pressure pipelines for water, gas and process effluents. Circular pipe from 75 mm to 2,700 mm and a variety of noncircular pipe such as egg shapes, ovals, and box culverts can be lined. Lining with CIPP removes the pipe…
ISTT
Curing Process
The uncured resin is designed so that, once the liner has been installed, the curing process can be completed while the liner is held against the interior of the host pipe and within a reasonable length of time. One approach is simply to allow the resin to cure under ambient conditions (i.e. at the temperature that…
ISTT
Curved / Gyroscopic
For curved microtunnelling, gyroscopic systems may be used - involving a north-seeking gyro-compass to track horizontal alignment and a remote water level gauge system for vertical alignment. As the diameter of the tunnel increases other options involving automated target-seeking theodolites can be used for…
ISTT
Deployment Methods
Inspection techniques may be deployed in a variety of ways, e.g. using a conventional crawler platform for CCTV systems, push-rod type camera systems, systems on floating platforms or, most recently, systems that use drones to navigate large-diamert pipes or tunnels.
ISTT
Depth / Elevation
Structurally, the groundwater level at a site controls the external groundwater pressure that will act on a pipe or installed liner. It also has an important impact on the provisions for face support in microtunneling or tunneling projects. It can also be important to assess fluctuations of groundwater levels over…
ISTT
Direct Steerable Pipe Thrusting (DSPT)
Direct Steerable Pipe Thrusting (DSPT) is a trenchless method where a thruster pushes a steel pipe string and microtunnelling machine along a designed bore path that can include both horizontal and vertical curves between shallow pits. This is in comparison to conventional microtunnelling, which uses pipe jacking from…
ISTT
Discrete Stress-Strain Sensors
Discrete stress-strain sensors can be used for special monitoring applications within undeground systems but the application environment and access limitations prevent their widespread use. In extended pipe networks, it is difficult to use hard wired sensors because of the cabling issues and the long-term functioning…
ISTT
Drill and Blast
Drill and blast tunnelling is used for tunnelling in rock. For such tunnelling, the rock is generally able to support itself for a period of time during the excavation process. A sequence of drilling boreholes in the tunnel face, loading the boreholes with explosive, firing the round and then removing the fragmented…
ISTT
Drone
Drone-based camera and laser surveying systems are recent additions to the options for inspecting and surveying in large pipes and tunnels. The drones can be programmed to fly within the confined environment.
ISTT
Earth-Pressure Balance (EPB)
In the earth-pressure balance (EPB) system, the excavation face is supported by matching the spoil removal rate from the face with the advance rate of the boring machine. If the advance rate is too slow, over excavation may occur - allowing ground settlement. If the advance rate is too high, then under excavation may…
ISTT
Electrical Tomography
Electrical or electromagnetic tomography uses geometrically-spaced measurements to infer a 3-D mapping of ground properties or objects located within the zone of interest. For example, measurements may involve differences in electromagnetic signals received as source and receivers locations are changed or record…
ISTT
Electromagnetic Environment
The electromagnetic environment encompassing a planned or existing buried utility can be important in assessing the potential for accelerated corrosion of buried metal structures and deciding how best to counteract that threat. This environment may include the presence of stray electrical currents in the ground and/or…
ISTT
Electromagnetic Methods
A variety of electromagnetic methods have been developed for the assessment of condition and corrosion in metal pipes – especially for use in critical and high value pipeline infrastructure such as oil and gas pipelines. Individual methods including magnetic flux, magnetic tomography, broadband electromagnetic,…
ISTT
Existing Pipe Displaced
Pipe bursting and pipe splitting are trenchless methods used to replace existing pipelines in the same alignment without physically removing the existing pipeline. Bursting and splitting, by using the existing alignment to replace a pipe, avoids the need to secure additional right-of-way to install the replacement…
ISTT
Existing Pipe Removed
In this category of pipe replacement, the existing pipe is removed as part of the replacement process. The three main methods used to accomplish this – pipe reaming , pipe eating and pipe extraction - are described separately. Removing the existing pipes without fragmentation is sometimes preferred for…
ISTT
External Void Detection
The detection of external voids can be very important in assessing the structural capacity of a buried pipe, tunnel or chamber. Voids in localized zones outside the structure create uneven loading of the structure and can allow distortion of the structure. Both of these effects can result in the failure of the…
ISTT
Fiber Optic Sensors
Fiber optic sensors can provide extremely sensitive sensor systems that are suitable for monitoring extended lengths of pipeline. Changes in environment such as temperature or changes in material behavior such as strain can be monitored at a remote location and associated with specific location(s) along the fiber.
ISTT