Glossary

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Jacking Force

Force applied to pipes in a pipe jacking operation.

Jacking Frame

A structural component that houses the hydraulic cylinders used to propel the microtunneling machine and pipeline. The jacking frame serves to distribute the thrust load to the pipeline and the reaction load to the shaft wall or thrust wall.

Jacking Pipe

A pipe with a flexible joint designed specifically for jacking.

Jacking Shaft

An excavation from which trenchless technology equipment is launched for the installation or removal of a pipeline, conduit, or cable. May include a thrust wall to spread reaction loads to the ground.

Jacking Shield

A fabricated steel cylinderat the front end of which excavation is carried out either by hand or by machine. Incorporated with the shield are facilities to allow it to be adjusted to control line and grade.

Jet Cutting

Guided boring method using pressurised fluid jets for soil cutting.

Joint

Flexible sealing and jointing arrangement between two pipes.

Joint Sealing

Method in which an inflatable packer is inserted into a pipeline to span a leaking joint, resin or grout is injected into the annulus between the packer and pipeline until the joint is sealed and the packer then removed.