Jacking Pipe: How Is an Infrastructure Line Installed Without Digging Up the Road?

Pipe jacking is a method developed for installing underground lines with less disruption to the use of the surface. In microtunnelling applications, remotely controlled excavation equipment and guidance systems are used. As the excavation advances, the pipe string behind it is pushed forward by hydraulic jacks; with suitable equipment, the method can also be applied at small diameters that do not permit human entry.

In this system, jacking and reception shafts are constructed. The jacks in the jacking shaft advance the pipe string; the excavated soil is removed by a method appropriate to the system used. Where necessary, intermediate jacking stations and friction-reducing lubrication are used. The number and location of the shafts and the working areas are determined according to project conditions.

For buried pipes, soil and traffic loads are the main actions; settlement and installation effects are also assessed. For jacking pipes, these are joined by the high axial jacking forces that arise during installation. The pipe body, end faces and joint details are designed taking all these effects into account:

• High axial compressive strength: The jacking force is transferred from the end face of one pipe to the next. The concrete class and reinforcement arrangement are selected according to this force.
• Tight manufacturing tolerances: The flatness of the end faces and their parallelism with each other are critical. Improper seating of the faces can disturb the load distribution, leading to local stress concentration and an increased risk of cracking.
• Smooth external surface and suitable joint: A joint geometry that does not protrude outwards eases advancement. Joint components such as the steel collar and gasket are arranged according to the design of the selected product.
• Load-distributing intermediate element at the joint: The pressure plate placed between two pipes spreads the force over the surface and accommodates small angular deviations in the line.

The value of a method is often seen not in the pipe itself but in its effect on the rest of the project.

• Less surface disruption: The need for open-cut excavation, backfilling and reinstatement of the surfacing along the route can be reduced. Traffic management or temporary closures may be required around the shafts and site areas.
• Method selection: The choice between open-cut excavation and jacking pipes is made by assessing together the length of the line, diameter, ground, groundwater, depth, shafts and equipment.
• Interference with existing infrastructure can be reduced: In congested infrastructure corridors, a controlled passage can be made between existing lines.
• Environmental impact can be reduced: Excavated spoil, haulage traffic and surface disruption can be reduced, depending on project conditions. Rivers and stream beds can be crossed without disturbing the bed.

• Crossings beneath highways and railways
• Lines beneath busy urban arterial roads
• Infrastructure crossings beneath river and stream beds
• Sea outfall lines beneath coastal structures and the shoreline
• Industrial zones, and energy and infrastructure corridors

Selecting a jacking pipe is not simply a matter of selecting a diameter. The soil class and groundwater conditions, the length of the line and the resulting total jacking force, the need for intermediate jacking stations, the locations and dimensions of the shafts, the burial depth and the superstructure loads are assessed together. These parameters determine both the pipe class and the installation plan.

Our products are manufactured within the quality and standards framework applicable to precast concrete and reinforced concrete pipe production; for project-specific diameter, class and length requirements, you can consult our technical team.