Failures in joints are among the most common sources of problems in buried gravity flowpipelines. Poor performance of these elements can cause infiltration and exfiltration, whichleads to soil erosion and eventually serviceability or strength limit states for the soil-structuresystem. To prevent this, joints should be designed to adequately accommodate the demandsgenerated under normal loading conditions. However, such demands are not clearly understood,since joint behavior has received scant attention. Thus the goal of this research is to examine theresponse of joints in two thermoplastic pipelines employed in gravity flow applications whensubjected to live loading. The specimens examined were a 1500 mm (60 in.) diameter HighDensity Polyethylene (HDPE) pipeline and a 900 mm (36 in.) diameter Polyvinyl Chloride(PVC) pipeline, both specimens with gasketed bell and spigot joints. Two burial depths and threedifferent loading locations were examined for each pipeline buried according to AASHTO Type2 installation. Moreover, two installations not specified by AASHTO were examined for thePVC specimen, which featured voids in the bedding under the joint. Finally, each specimen wasloaded directly over the joint up to and beyond fully factored loads to observe the jointperformance under this condition and the final failure mode of the pipelines. The specimens wereinstrumented with string potentiometers and reflective prisms to monitor changes in diameter inthe joint and barrels, and to obtain patterns of vertical displacements along the pipeline. Theobserved response for each pipeline is presented and discussed here, and recommendations aremade regarding the development of structural design procedures.
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