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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 409–432
Preliminary Inspection
Due to the extent of buried infrastructure assets to be inspected and managed and the limited budgets available for inspection and rehabilitation, it is necessary to carry out preliminary assessments to establish priorities for this work. Identifying the areas most needing inspection can involve analyzing operational…
ISTT
Pressure Monitoring and Detection
Differential pressure monitoring in different parts of a pipeline system may show up pressure anomalies that indicate a leak. The most direct means of determining whether there is a leak in a part of the system or in a particular section of pipe is to isolate that part of the system and subject it to a pressure test.…
ISTT
Push-Pull Satellite Camera
Inspection cameras for smaller diameter pipes or laterals are often simply pushed through the pipe using a flexible rod/cable system. The camera may be combined with a sonde device for tracing the pipe alignment. For inspecting lateral pipes connected to a mainline sewer, a satellite camera system may be added to be…
ISTT
Quality
Groundwater quality in terms of its chemical and biological constituents can be important to determine both for construction implications and for any impacts on the long-term performance of the installed or rehabilitated utility system. Examples include checking for chemicals that may impact the behavior of drilling…
ISTT
Ram-assist Technologies
In this group of hybrid methods, trenchless drilling or tunnel boring or pipe installation techniques are enhanced by adding impact energy or hammering assistance to the basic method. Typical applications include: rock drilling techniques using a hammer drill for HDD applications pipe installation assist for HDD (or…
ISTT
Ramming / Impact
This subset of methods uses an impact or hammering approach to advance a pipe through the soil. More specific descriptions are provided for each method.
ISTT
Reduced Surface Disturbance
In this category are methods that do create a continuous disturbance to the ground surface while installing a new pipe or cable but reduce the amount of surface disturbance by using plowing techniques or cutting a narrow and easily patched slot in a pavement or other ground surface.
ISTT
Rehabilitation
This class of methods is focused on the rehabilitation of existing utility pipes to restore performance and/or avoid failure of those pipes. This class of rehabilitation methods is subdivided into “Renovation” (which upgrades the structure and/or improves protection or performance of sections of the…
ISTT
Renovation
There are many trenchless renovation methods that have been developed in the past several decades. Some can be generally applied in a wide range of existing pipes and underground structures, others have a much narrower range of application. All allow new linings or coatings to be installed within existing pipes or…
ISTT
Renovation Slip Lining
Slip lining with an inserted pipe used for “renovation” purposes may utilize the same techniques as in “replacement slip lining” (where the methods are described more fully). The distinctions between the renovation and replacement categories depend on the extent to which the liner will function…
ISTT
Repair
The term “repair” is used here to denote methods that are targeted at local defects in a pipe – even if those local defects are widely distributed with the pipe system. The main difference from “renovation” is that, in repair-focused techniques, the main body of the pipe does not receive…
ISTT
Replacement
The term “replacement” is used here to denote that a new pipe (or the full equivalent of a new pipe) is being installed in the same space that is currently occupied by the existing pipe. This can be important in crowded rights-of-way where space to install a new pipe on another alignment may be very…
ISTT
Replacement Slip Lining
In this replacement application a new pipe of smaller outside diameter than the inside diameter of the existing pipe is inserted (pushed or pulled) within the existing pipe and provides a complete replacement of the structural and flow functions of the existing pipe. This is usually referred to as slip lining . In…
ISTT
Resistivity Measurements
Resistivity measurements between different points on the ground surface or between different points in a borehole or pipe and different ground surface locations allow inference about the zonation of different ground conditions with different conductive properties.
ISTT
Robotic Repairs
Robotic systems play a significant part in trenchless technology construction. Not only are they used for surveying and monitoring, but also for localised repairs. The robots are inserted into the pipeline and remotely controlled by an operator on the surface. Essentially the robots comprise a wheeled motorised…
ISTT
Rolled Down Lining
In this category of close-fit linings in which the plastic lining pipe (typically polyethylene) is sized to fit tightly inside the existing host pipe. To allow the insertion of the lining pipe, the lining pipe is reduced in diameter just prior to installation, pulled into place and then expanded again within the host…
ISTT
Seismic / Sonar Techniques
The term "sonar" is typically used when a sound (compression) wave is propagated in water and the term "seismic" is associated with a family of techniques that infer information on buried objects or geological strata changes by propating compression or shear waves into the ground. When sound waves are emitted and…
ISTT
Site Investigation
Site investigation is an important precursor to most construction projects - whether they involve new installation or rehabilitation. The methods focused on here are those that can be carried out with minimal surface distubance. Two important aspects of site investigation are to determine: What structures or utilities…
ISTT
Slant-face drill bit
The most common steering mechanism involves a slant-face drill bit, the orientation of which determines the direction that the bit will advance. To move in a straight line, the rig operator both rotates and pushes the drill string. To change direction, the operator, stops rotating the drill string and pushes the…
ISTT
Slurry
Pumping a mud slurry to the face chamber in a microtunnelling machine both allows the slurry pressure in the chamber to support the tunnel face and allows the excavated soil to mix with the slurry and be pumped to the ground surface via a return line. The excavated soil is then separated from the slurry and the slurry…
ISTT
Smoke and Dye Testing
Dye testing is used to determine if surcharge in a drainage system area is in fact sewage effluent. Dye testing is also used to determine the flow of water through pipes and sewers. A smoke test can be done to help determine if there is a broken or separated pipe, and it can also determine the location of leaks.
ISTT
Soft-ground Shield
In a typical project, a soft-ground shield is a tunnel technique that uses a steel cylinder to support the ground surrounding the tunnel near the excavation face and to provide a safe zone in which the excavation can be conducted and the tunnel lining can be erected. Depending on the stability of the ground in the…
ISTT
Soil Sampling
Soil sampling is an important part of the site/ground investigation process. It is typically carried out by drilling boreholes spaced at intervals along (but not directly within) the alignment of a project with extra boreholes located where additional information is needed for project design. The boreholes usally are…
ISTT
Soil/Rock TBM
A large proportion of tunnel projects are excavated by a Tunnel Boring Machine or TBM. These machines provide a system of equipment for excavating and supporting the ground at the face of the tunnel, removing and transporting the exavated ground to the surface, and installing any necessary ground support to keep the…
ISTT