Pipe bursting is defined as a replacement method in which an existing pipe is broken by brittle fracture, using mechanically applied force from within. The pipe fragments are forced into the surrounding ground. At the same time, a new pipe, of the same or larger diameter, is drawn in replacing the existing pipe. Pipe bursting involves the insertion of a conically shaped tool (bursting head) into the existing pipe to shatter the existing pipe and forces its fragments into the surrounding soil by pneumatic or hydraulic action. A new pipe is pulled or pushed in (depending on the type of the new pipe) behind the bursting head.
The base of the bursting head is larger than the inside diameter of the existing pipe and slightly larger than the outside diameter of the new pipe to reduce friction and to provide space for maneuvering the pipe. The back end of the bursting head is connected to the new pipe and the front end is connected to a cable or pulling rod. The new pipe and bursting head are launched from the insertion shaft, and the cable or pulling rod is pulled from the pulling shaft. The bursting head is usually attached to other components to lengthen the bursting body to reduce the effects of sags or misalignment on the new pipeline.
Some bursting tools are equipped with expanding crushing arms, sectional ribs, or sharp blades to transfer point or line loads to the existing pipe to assist in bursting. The bursting head receives pulling force to break the existing pipe from the pulling cable or rods, hydraulic power to the head, or pneumatic power to the head based on the bursting system. The pulling force is transferred to the existing pipe breaking it into pieces and expanding the diameter of the cavity. The bursting head is pulled through the pipe debris creating a cavity and pulling behind it the new pipe from the insertion shaft. The basic difference among these systems is in the source of pulling force and some consequent differences in operation.
The pipe bursting method creates a cavity in the soil around the pipe where the new pipe is pulled through. The cavity creates a compression plastic zone around the new pipe outlined by an elastic zone. The magnitude of the compression and the dimensions of these zones correlate with the amount of upsizing, the diameter of the pipe, and the type of soil.