Page 23 - Buried Pipe Design
P. 23
Chapter
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Introduction and Overview
Underground conduits have served to improve people’s standard of liv-
ing since the dawn of civilization. Remnants of such structures from
ancient civilizations have been found in Europe, Asia, and even the
western hemisphere, where some of the ancient inhabitants of South
and Central America had water and sewer systems. These early engi-
neering structures are often referred to as examples of the art of engi-
neering. Nevertheless, whether art or science, engineers and scientists
still stand amazed at these early water and sewer projects. They seem
to bridge the gap between ancient and modern engineering practices.
The gap referred to here is that period known as the “dark ages” in
which little or no subsurface construction was practiced—a time when
most of the ancient art was lost.
Today, underground conduits serve in diverse applications such as
sewer lines, drain lines, water mains, gas lines, telephone and electri-
cal conduits, culverts, oil lines, coal slurry lines, subway tunnels, and
heat distribution lines. It is now possible to use engineering science to
design these underground conduits with a degree of precision compara-
ble with that obtained in designing buildings and bridges. In the early
1900s, Anson Marston developed a method of calculating the earth load
to which a buried conduit is subjected in service. This method, the
Marston load theory, serves to predict the supporting strength of pipe
under various installation conditions. M. G. Spangler, working with
Marston, developed a theory for flexible pipe design. In addition, much
testing and research have produced quantities of empirical data which
also can be used in the design process. Digital computers, combined
with finite element techniques and sophisticated soil models, have
given the engineering profession design tools which have produced, and
will undoubtedly continue to produce, even more precise designs.
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