Pipe Jacking

Definition:

Pipe jacking is a trenchless method used for the installation of underground pipelines, conduits, and culverts. It involves pushing or jacking a prefabricated pipe through the ground using hydraulic or mechanical means, without the need for excavation along the entire length of the pipeline. This method is commonly employed in tunneling and underground construction projects to minimize surface disruption and reduce the impact on existing structures.

Uses/benefits:

Underground utilities: Pipe jacking is widely used for the installation of various underground utilities, including water and sewer pipelines, drainage systems, gas and oil pipelines, and telecommunications conduits.
Road and railway crossings: Pipe jacking is an efficient method for installing pipelines under roads, highways, railways, and other sensitive areas, eliminating the need for disruptive excavation and minimizing traffic disruptions.
Environmental and sensitive areas: The trenchless nature of pipe jacking makes it suitable for installations in environmentally sensitive areas, such as wetlands, protected habitats, and historical sites, where preservation and minimal disturbance are essential.
Urban areas: Pipe jacking is commonly employed in urban areas with high population density, where open excavation would cause significant disruptions to traffic, businesses, and residents.

Specifications:

Pipe material: Pipe jacking can be performed using various pipe materials, including concrete, steel, PVC, HDPE, and composite pipes, depending on the project requirements and design considerations.
Pipe diameter: The diameter of the pipes used in pipe jacking projects can vary significantly, ranging from small-diameter conduits to large-diameter pipelines for water and wastewater applications.
Pipe lengths: Pipes used in pipe jacking are typically manufactured in shorter sections that can be joined together during the installation process. The length of the pipe sections depends on factors such as ground conditions and jacking equipment capabilities.
Excavation pit and launch shaft: Pipe jacking requires the construction of an excavation pit or launch shaft from where the pipes are inserted and pushed into the ground. The dimensions and specifications of these structures depend on the pipe size, ground conditions, and jacking method used.

Types:

Auger boring: This pipe jacking method utilizes a rotating auger to excavate the soil in front of the pipe, creating a bore path for the pipe installation. The pipe is then pushed into the bore path using hydraulic jacks.
Slurry microtunneling: Slurry microtunneling involves the use of a pipe jacking machine that pushes the pipe through the ground while a bentonite slurry is used to stabilize the excavated soil and transport it back to the launch shaft.
Pipe ramming: Pipe ramming is a method where a pneumatic hammer or ram is used to drive the pipe into the ground while soil is removed using compressed air or water jets. This method is suitable for shorter distances and smaller diameter pipes.
Guided boring: Guided boring combines the use of a pilot tube and a jacking frame to install pipes accurately. The pilot tube is advanced using a boring machine, and the pipe is then jacked into place following the pilot tube path.

Pipe jacking offers several benefits, including reduced excavation, minimal disruption to surface activities, shorter construction time, and lower impact on the environment. It allows for the installation of pipelines in challenging ground conditions and congested areas. Proper design, ground investigation, and selection of the appropriate pipe material and jacking method are crucial for successful pipe jacking projects in tunneling and underground structures.