An analytical parametric study of uplifting resistance in buried pipelines

ABSTRACT: Offshore pipelines are frequently used to transport hydrocarbons and gases to various areas in the world. Often, they are buried in trenches for a variety of reasons. Reasons include safety for the pipe from obstructions or to provide stability and to protect against accidental loads etc. The material in the pipes is often transported at high temperatures and pressures to facilitate the flow of the oil or gas. These conditions cause an increased amount of force on the interior of the pipeline, causing movement of the pipeline upward, which is called upheaval buckling. With buried pipelines, the predominant direction of motion will be in the path of least resistance, which would be a longitudinal profile imperfection triggering upheaval movement in a vertical direction. This movement of the pipeline could lead to the failures in the line, halting production, requiring repairs to the system, and dire environmental effects. The design of pipelines against upheaval buckling is a challenging aspect of their design. Accurate assessment of upheaval buckling needs advanced numerical simulations and/or experimental studies, which would be costly and time-consuming. The analytical solutions are fast and acceptably accurate, particularly for early stages of design. In this study, the effect of the key parameters contributing to the upheaval buckling of buried pipelines was analytically investigated. Key geomechanical soil parameters and rate effects were examined, and their effect on vertical pipeline-soil interaction during the upheaval buckling were investigated. Several invaluable trends were observed providing a good insight into the sufficiency of the analytical solutions.