Performance of Buried HDPE Pipes
Associate professor of Geotechnical Engineering
This paper presents the effect of temperature on the deformation characteristics and performance of buried High-Density Polyethylene (HDPE) pipes. The testing program consisted of line loading of ring pipe samples submerged in water heated to prescribed temperatures of 30, 40, 50, 60, and 70 oC. Nonlinear finite element program (Z-Soil) is used to back calculate the secant deformation moduli and yield strengths for HDPE pipes at various temperatures. Simple elastoplastic constitutive model which captures measured load-deformation response up to 6% vertical deflection is employed. Experimental results reflect deformation modulus, yield strength, and unrecoverable strain decrease with increasing temperature. The calibrated numerical tool is used to predict performance of buried HDPE pipes at various temperatures. Two Installation and two operation procedures are investigated. Medium dense and dense sands are considered for modeling staged pipe backfill and cover with incrementally increasing surface and internal pressures. It is shown that, pipe horizontal deformation slightly increases with temperature and slightly decreases with internal pressure. Buried HDPE pipes perform well under considered surface pressure, internal pressure, and installation conditions even at elevated temperature in the range 30 to 70 oC.
Keywords: High-Density Polyethylene Pipes, Temperature, Buried pipes, Backfill, Cover, Deformation.
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