Tension Analysis Of Submarine Cables During Laying Operations

With the increasing expansion and utilization of oceanic natural resources, the critical importance of marine cable laying technology is more and more obvious in the commercial business and military fields, which attracts many experts and scholars dedicated to this issue. Despite of more than one century development, the cable laying project still exists a lot of key problems to be investigated for the hostile operating environment. Accurate numerical simulation for cable laying is necessary to ensure the safety and reliability of cables installation. Subjected to gravity force, buoyancy, added mass forces and inertia forces, submarine cables can also be affected by the cable laying vessel velocity, pay-out rate and current profile during laying operation. Based on former research results, the paper mainly focuses on the kinematics and tension analysis of submarine cables, which aims to build the numerical model and investigate the cable tension distribution. Numerical cases are conducted to study the relationship between the tension force and various key parameters and give the design formulas. The tension force distribution and curve configuration can be predicted through the governing equation.In this paper, we assumed that submarine cables are ideal flexural structures with axial extension taken into consideration. Based on the equilibrium equations, the kinematical equations are obtained for threedimension with various environmental loads. The finite difference method is adapted to discrete the marine cable. Hence, a set of ordinary differential equations can be obtained through the partial differential equation. With the tools of MATLAB package, we adopt four-order Runge-Kutta method to get the integration in the spatial. Boundary and initial conditions are given for the case of cable laying with slack and certain tension forces at the touch down point, respectively. Comparisons between numerical results and experimental data & other published paper are done to validate the numerical model.Finally, numerical simulations are conducted for tele-communication cable to study the dynamic response when the cable laying vessel changes its motion state. In addition to, parametric analysis is studied in the South China & Hainan Island Power Grid interconnection projection for steady state. Parameters and environmental conditions are discussed in detail to investigate the influence on marine cables during laying operations, including cable laying vessel velocity, current profile, pre-tension at the touch down point. The numerical results show that cable laying vessel velocity, current profile, pre-tension at the touch down point and self-weight are significant for the configuration during laying. While the tension forces in marine cables mainly depend upon water depth, self-weight and the tangential drag coefficient.