Date of Award

Winter 1998

Document Type

Dissertation

Degree Name

Doctor of Engineering (DEng)

Department

Materials and Infrastructure Systems

First Advisor

Ray Sterling

Abstract

This dissertation has involved field and analytical studies of ground movements, ground vibrations and other design issues associated with trenchless pipe replacement (or pipe bursting, as it is commonly known). The process is used to replace an existing underground service pipe with a completely new pipe but without the disturbance and cost of excavating a trench from the surface. The process typically involves the insertion of a tool into the existing pipe that has a maximum diameter that is slightly larger than the existing pipe. This tool is used to break the existing pipe into pieces and to displace the pieces and neighboring soil outwards into the surrounding ground while a new pipe is installed behind the tool. There are several variations of the process with different approaches to various aspects of the breakage and replacement.

The trenchless pipe replacement offers advantages of low cost, reduced surface disturbance, and the ability to replace an old pipe with a new pipe of equal or larger diameter and capacity Concerns about the use of the method have centered principally on the ground movements and vibrations produced by the technique--particularly when existing pipe is being replaced by a larger diameter pipe-- and also on any damage experienced by the replacement pipe as it is being pulled into the ground.

By further development of the understanding of the effects of the process and by refining the safe limits for the replacement process in terms of soil type, groundwater conditions, type of pipe being burst, degree of up-sizing, proximity to existing services, depth below the street, etc., it is expected that many of the concerns expressed by owners and consultants about the use of the techniques will be allayed and attention directed to the particular circumstances where special precautions need to be used. The cost advantages inherent in on-line replacement over open-cut replacement in many circumstances, and the resulting potential growth of this market, make the improved understanding of ground movements and impacts on adjacent structures well worthwhile.

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