Pipeline breakout from sea floor under wave action

Abstract The vertical stability of a submarine pipeline laid half-buried on the sea floor under wave action is studied. As the wave-induced lifting force acts to detach the pipe from the sea floor, mud suction resistance will be developing at pipe-soil interface, acting to hold the pipe in place. This couples the pipe equilibrium with the seabed response which is modelled as a poroelastic media, following the formulation of Biot. Conditions for pipe detachment or breakout from the sea floor are investigated for typical seawave, pipe, and seabed parameters. A general power law will describe the slow quasistatic breakout of the pipe. In the case when the forcing wave period is much shorter than the quasistatic breakout time, the response function of the coupled pipe-seabed system will involve weak nonlinear terms of higher harmonics. The possibilities for resonating the system in such case are examined by including the inertia of the pipe in the analysis.