Simulation Study on the Behavior of Submarine Cable Suspension Span Section under the Effect of Ocean Current Scouring

Abstract

When the suspension span exceeds a certain length, the submarine cable may be scoured by ocean currents or lead to vortex-induced vibration, which may cause mechanical damage. Currently, the occurrence conditions of vortex-induced vibration and the influence mechanism of ocean current scour on the submarine cable are unclear. Based on this, a three-dimensional finite element model of ± 500kV direct current optical fiber composite submarine cable with a suspension span section length of 1.6 m subjected to ocean currents is established in this paper. The influence of ocean current scour on submarine cable and its sensing optical unit when the submarine cable is disturbed under a fixed seawater flow rate is investigated. The inherent disturbance frequency of the model is obtained through the modal analysis study. Moreover, the disturbance behavior of the submarine cable is analyzed using the flow-solid coupling method. At last, Fourier analysis of the time-displacement curve of the optical unit center point is performed. The results show that the characteristic disturbance frequency of the first-order modal for the model is 201.55 Hz. The stresses and displacements of the optical unit are symmetrically distributed. Among them, the stress at both ends is the largest. Amplitude extreme is generated at disturbance frequencies of 0.4 Hz in the center of the optical unit. According to this study, we provide data reference for the operational state sensing of submarine cables.