Rerounding of Deflected Buried Pipe Subjected to Internal Pressure

This paper presents a theoretical basis for the rerounding effect of internal pressure on deflection and stresses in buried pipe. The nonlinear differential equations governing pipe-soil interaction of deflected buried flexible or semi-rigid pipe surrounded by soil of known stiffness subjected to internal pressure is derived. The solution of the problem provides a rerounding factor that reduces the installation-induced deflections and bending stresses in the pipe wall. The rerounding factor derived expresses the extent of stress reduction from rerounding on internal pressure, pipe bending and axial stiffness, and soil stiffness. The rerounding factor provides an analytical method to determine the stresses in a flexible buried pipe subjected to combined effects of earth load and internal pressure. It is hence applicable to metallic pipe, fiberglass pipe, HDPE pipe, CFRP liners as well as semi-rigid concrete pipe, such as bar-wrapped pipe.