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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