Numerical procedure for static and dynamic analysis of fluid-conveying submarine pipeline span on linear elastic seabed

Based on the Hamilton principle, dynamic differential equation of the submarine pipeline span, under the interaction of internal flow and external environmental loads, is established. A constraint-equivalent method is used to deal with the boundary conditions of pipeline span on the linear elastic seabed. Effects of the internal flow velocity and seabed stiffness on the pipeline’s lateral deformation and bending stress are studied by the static analysis, while the preliminary relationships between the internal flow velocity and the foundation stiffness to the natural frequency of pipeline span are investigated by the dynamic analysis. It is found that the lateral deformation increases with the increment of internal flow velocity, but decreases with the increment of seabed stiffness. The bending stress at the ends of span increases with the increment of internal fluid velocity and the seabed stiffness, however the stress at the middle of the span shows the converse tendency. Moreover, increasing the seabed stiffness or decreasing the internal flow velocity can lead to higher natural frequency. The dynamics response of midpoint of span at different foundations and internal fluid velocities are also given in this paper.