Mode localization in lateral buckling of partially embedded submarine pipelines

AbstractThe partially embedded submarine pipelines might buckle laterally at some segments under high pressure and high temperature (HP/HT) conditions. The buckling pattern localization introduces an extra level of analytical complexity when compared with the periodic buckling pattern. In the presented paper the lateral buckling pipeline is modeled by an axial compressive beam supported by lateral distributing nonlinear springs taking the soil berm effects in the horizontal plane. It is found that the model is governed by a time-independent Swift–Hohenberg equation. Based on John Burke and Edgar Knobloch’s work we conclude preliminarily that the equation will have localized solutions. Besides the qualitative conclusion, by AUTO 07P the localized solutions of the equation are studied in detail. The snakes-and-ladders structure of localized solutions explains the transition of buckling modes in theory. The range of the possible critical axial forces is found out. Meanwhile two critical axial force formulas corresponding to the range ends are presented. Finally a typical submarine pipeline is analyzed as an illustration