Hydraulics for Underground Piping and Cabling

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Hydraulics for Underground Piping and Cabling

In recent times, you can find many instances that require underground piping and cabling. Nowadays, underground installations are used for electric, phone, and data cable connections and this method will reduce the danger to a greater extend and isolate it from its surroundings. The traditional approach of digging trenches and laying cables is currently not acceptable. Such approaches will consume much time and will require greater effort for digging and then restoring the soil after laying pipes or cables. The benefits of trenchless methods are reduced surface destruction, less manpower requirement, equipment mobility, and more.

We can categorize the process of underground piping and cabling into the open-cut method and no-dig method. The open-cut method is the traditional method that includes digging trenches as we mentioned above. The no-dig method is one that utilizes special equipment and machines for drilling underground holes for laying cables and pipes. Horizontal directional drilling and pipe jacking are the two important classifications of the no-dig method. In both of these methods, two pits are created in the required depth at both ends, called thrust pit and reception pit.

Also Read: Hydraulics in Tunnel Boring

Horizontal directional drilling is a minimal impact trenchless method that utilizes drilling machines and associated attachments for laying cables and pipes. The process of drilling involves placing the drilling machine on one end and from there, an underground hole is drilled to the other end. Directional drilling has three stages like the pilot hole, pre-reaming, and pipe pull-back. A pilot hole is the first stage where a small diameter hole is drilled by passing high-pressure jets of drilling fluid through the drill pipe to grind the soils ahead. The second stage is pre-ream that aims to enlarge the size of the hole to safely install the product lines. In this stage, a rotating reamer connected onto a drill pipe constructed with PVC, polyethylene, polypropylene, ductile iron, and steel is pulled through the pilot hole, and at the same time, the machine will pump drilling fluid also. The reamer will enlarge the pilot hole into the required diameter. The last stage of this horizontal directional drilling is the pullback of the pipe.

Pipe jacking, also known as ramming is another trenchless method that involves the installation of pipes underground the earth. For constructing pipelines, ducts, and culverts using pipe jacking methodology, the system will require a powerful hydraulic jack to push the prefabricated pipes from one end to another. The result of using a pipe jacking trenchless method will be a flexible, structural, watertight, finished pipeline. This method provides excellent ground support and minimizes ground movement to a greater extend. The thrust power is utilized by the hydraulic jack for installing steel pipes and casing. When each pipe is pushed completely into the ground, the ram on the hydraulic jack will retract and helps the next pipe to be positioned. This process will continue until the required length is covered. Depending on the diameter of the pipe, the excavated soil can be removed either manually or mechanically. The pipe jacking methodology also fills the empty spaces with mortar to make it more stable.

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