Page 153 - Trenchless Technology Piping Installation and Inspection

CHAPTER 4

Pipe and

Pipe Installation

Considerations

4.1 Introduction
Pipeline construction has considerable uncertainties owing to the
complex nature of the pipe-soil system. More complexity applies to
trenchless methods when a machine is used to install the pipe blindly.
However, trenchless technology only disturbs the ground in the area
of pipe zone, but open-cut disturbs the soil from the ground surface.
Structural designs of pipelines employ models for calculation of
different behavioral factors such as deflection, buckling, cracking,
and so on, that are based on particular assumptions for interaction
between pipe and soil. Since pipe and soil are typically designed as
integral systems, it is crucial that the construction process achieves
this design objective. While project plans and specifications provide
the basic requirements for construction and installation, the site con-
ditions often vary from those anticipated during design. These vari-
ations must be considered by the contractor and construction
engineer. Often, alternate or additional construction considerations
are necessary to address unexpected or unspecified conditions.

4.2 Pipeline Construction Using Open-Cut Method
Pipeline installation using open-cut method involves mobilization of
material, labor, and machinery to obtain, assemble, install, inspect,
and test the pipeline system. Underground pipeline installation may
seem relatively straightforward: (1) dig a trench, (2) lay the pipe in the
trench, and (3) fill the trench back in. However, in reality, pipeline
installation involves many important engineering and construction
considerations. An underground pipeline system incorporates both

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