LOCAL BUCKLING OF DENTED SUBSEA PIPELINES UNDER THE COMBINED LOADINGS

摘要

Dents has long been regarded as a potential hazard for integrity of subsea pipelines in the oil and gas industry. The dents in subsea pipeline are usually caused by the collision and extrusion with other objects resulting in permanent plastic deformation in pipe wall. Meanwhile, seabed deformation or motion due to subsidence, mudslides, and seismic activities may load the pipeline to an ultimate state, where the pipeline is under combined external pressure and bending moment. It is of great importance to carry out the research on the buckling failure and bending capacity of dented subsea pipelines under these combined loads. Nonlinear finite element method is adopted to investigate the local buckling failure of the dented subsea pipeline under combined loads. The numerical results show that the buckling behavior and bending capacity of the pipeline can be largely reduced due to the existence of external pressure and axial force. Based on numerical results, a formula for predicting the bending capacity of dented subsea pipelines is proposed. Finally, the accuracy of propose solution is validated.