Pipe Bursting Large Diameter Pipe - Class C Pipe Bursting

8th In A Series From The IPBA
By Matt Timberlake, President, Ted Berry, Trenchless Technologies Team LLC, International Pipe Bursting Association Marketing Committee | December 2011, Vol. 66 No. 12
Class C bursting diagram.

As the soil is expanded up and out, the center line of the new pipe will change in relation to the center line of the existing pipe. The invert in most soil conditions will follow that of the existing pipe elevation and slope. As the center line of the new pipe changes considerations must be made for reconnecting service laterals or other connections. Depth of cover calculation can be taken to determine if the expansion upwards has the potential to cause ground heave, this calculation is dependent on the volumetric displacement calculation which is a direct relationship between the ID of the existing pipe and the OD of the expander so when upsizing of the existing pipe is being performed the depth of cover must be greater. (See insert image)

Make data available
In the design stage of a project, it is essential that all applicable information is made available to the project team or potential bidders as this data will help the team determine the type and size of equipment that is best suited for the specific project, as well as begin building contingency plans for construction activities. Job site logistics and pit locations are critical to any trenchless project and considerations must be made for actual location, size and specific requirements of pipe bursting pits. Large diameter pipe bursting project will require detailed geotechnical data as actual soil conditions will impact both the expansion force and drag calculation.

The two most common types of pipes installed for large diameter pipe bursting are HDPE and fusible PVC (FPVC), both of which are installed in continuous segments, although FPVC can only be installed by static means. Handling, fusing and inserting large diameter pipes is much more challenging than as is common with smaller diameter pipes.

A large diameter HDPE pipe is shown at the insertion pit with the 			burst head entering the existing pipe.

It is important that everyone involved have a good understanding of the pipe being installed and the considerations that must be made in the field for an installation of a continuous length of pipe and the tools, hoses, etc. that are attached to it during the installation. Resources and manpower required for maneuvering pipe into the insertion pit and maintaining the proper insertion angle should be a defined part of the installation plan. Actual insertion pit lengths are calculations based on the bend radius of the pipe being installed and the depth of the existing pipe. These calculations vary by pipe size, SDR and pipe type, and should again be a defined part of the installation plan.

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