In 1941, Marston’s student Merlin Spangler, known today as “the father of buried flexible pipe design,” published another ground-breaking paper, “The Structural Design of Flexible Pipe Culverts,” in which he derived an equation, the Iowa Formula, for predicting the ring deflection of buried flexible pipes. This became, in part, the very foundation on which much of the later work around the world on earth loading technology of buried pipes was based. Thus was defined the Marston Theory of Loads on buried conduits. In 1913, and 1930, Marston published his original papers “The Theory of Loads on Pipes in Ditches and Tests of Cement and Clay Drain Tile and Sewer Pipe” and “The Theory of External Loads on Closed Conduits in the Light of the Latest Experiments,” respectively, marking the earliest systematic approach of studying the structural mechanics of buried pipes. But a tremendous amount of research in the last two decades now provides design engineers and contractors with an understanding of the pipe-soil mechanics of pipelines built by methods other than traditional open-trench methods. While trenchless technology is no longer in its infancy, the only known and practiced trenchless construction methods during Marston’s lifetime included jacking and tunneling, and little else. Another relatively new construction method in buried pipeline construction and rehabilitation is the advent of trenchless technology. Our knowledge of pipe-soil interaction, as well as the development of new pipe materials and the improvement of traditional ones, has grown by leaps and bounds since those early days, leading to a multi-billion dollar global pipe materials industry. Marston was the first Chairman of the federal Highway Research Board. It was necessary to design them properly so that they would not fail.īuried pipe design, then, was inextricably connected to the development of highway systems in the United States. Research was also necessary as thousands of small wooden bridges were being replaced by concrete and clay pipes placed in stream beds underneath roadway embankments. Anson Marston, then Dean of Engineering at the Iowa State College (now Iowa State University) and the first Chairman of the Iowa State Highway Commission, analyzed soil pressures on buried culverts in an effort to drain muddy rural roads. The story of the formal study of buried pipe structures in North America begins in Ames, Iowa, at the turn of the 20th Century, when Dr. In municipal pressure piping systems, the internal pressure is typically much greater than soil pressure on the pipe internal pressure essentially supports the soil load when the line is placed into service. While an understanding of pipe-soil interaction is important for the sound structural design of pipelines, it should be noted that the concern for soil pressure on a pipe is limited to empty pipe or gravity flow pipelines where the conduit never flows full. The latter can only be ensured through a thorough understanding of and designing for the loads to which a buried pipe will be exposed, its response to the loading, and the interaction mechanism between the pipe and surrounding soils. Whatever the material type, all are expected to provide some minimum service qualities: prevention of leaks, which ensure that potable water isn’t compromised by contaminants entering a piping system and that wastewaters do not pollute soils and existing sources of groundwater, and most importantly, that the structural soundness of a buried pipe system results in a minimum service life of 50 to 100 years.
These intricate networks consist of various types of pipe materials that range from metals to concrete to plastics to composites. The very basic services that we take for granted, such as a running faucet with clean drinking water and the ability of our wastewater to be transported away from our homes and businesses for treatment and release into the environment, are possible because of the vast network of buried pipes that lie hidden beneath roads and the concrete jungles that define the large urban centers that are our cities. Buried pipelines for the conveyance of potable water and sanitary sewers form the bedrock of our civilization.