Seismic analysis and design of offshore pipelines
Proceedings Publication Date
The discovery of hydrocarbons in combination with the need for transportation among countries has recently made the optimization of the design, construction and operation of offshore pipelines very important issue. Offshore pipelines are usually crossing extended areas, and therefore they may face various geohazards that potentially threaten their integrity by imposing permanent ground deformations. In areas characterized by seismicity the risk is higher due to the earthquake-related geohazards, such as earthquake-triggered landslides, soil liquefaction phenomena, and active faults. Although there exists a great experience in offshore geotechnics and pipeline design, the experience in seismic design of offshore pipelines is rather limited as most of the pipelines have been constructed in non-seismic regions (e.g. North Sea, Gulf of Mexico, etc.). The current study focuses on the seismic analysis and design of offshore pipelines. Due to the lack of related seismic norms worldwide, the study includes a description of the main earthquake-related geohazards and a brief review of the available methods of quantitative assessment. Finally, the study includes some parametrical numerical simulations with special emphasis to pipeline crossings with active faults that usually cannot be avoided by rerouting. After some interesting conclusions regarding the seismic vulnerability of offshore pipelines, potential mitigation measures are proposed.