The sensitivity analysis on vortex-induced vibration of submarine pipeline spans

Vortex induced vibration can cause fatigue failure of submarine pipeline span, and the vibration frequency, natural frequency and vibration load are the main influencing factors. The natural frequency is the index to characterize the sensitive degree of structure to the load, and the pipeline span resonance can occur only when the vortex main issuing frequency is close to the natural frequency of pipe-soil structure. This paper analyzes the influence law of the mechanics properties of subsea soil, span length, pipe size, current velocity on vortex induced vibration of submarine pipeline spans, and the results show that with the increase of hardness of pipeline covering layer, the maximum stress location of a pipeline span gradually moves from the midpoint of the span to the interfacing area between the soil and the pipeline span. When the current velocity is greater, the fatigue failure easily occurs close to the midpoint of the span and two ends of the span for small diameter submarine pipelines, paying attention to the locations where fatigue failures easily occur in engineering design and verification process can help to improve the reliability of submarine pipelines.