Elimination of Deflection of Elliptic Pipes Caused by Internal Pressure

Abstract

In designing and construction management for pipelines using flexible pipes, sectional deflection is controlled within the range which is specified by technical standard. To estimate the deflection, external earth pressure, weight of water in the pipe, and restraint by backfill soil are considered as loads and supports, but internal pressure during the operation of pipeline is not yet considered. Aiming the formulation of the elimination amount of deflection caused by internal pressure, frame analyses are conducted for oval pipes under internal pressure. Obtained displacements are formulated by multiple regression analyses and a differential equation between radius difference and internal pressure is derived. By integrating this equation an exponential function is obtained, which shows that the difference in radii exponentially reduces and approaches to zero according to the increase in internal pressure.