铺缆船与电缆耦合系统动力学分析

Dynamic Analysis of Cable-Laying Vessel and Submarine Cable Coupling System

提出一种铺缆船与电缆耦合系统动力响应时域分析方法。针对“启帆9”号铺缆船进行了船模阻力试验,得到铺缆船阻力系数,以确定其流载荷。基于势流理论,使用AQWA软件对铺缆船进行频域水动力分析,以确定其波浪载荷。结合上述计算结果,使用动力学分析软件Orca Flex建立了基于海底电缆铺设过程的耦合动力学模型,通过对考虑了环境载荷、系泊载荷和电缆载荷的动力学方程进行求解得到铺缆船动力学响应,将铺缆船运动作为电缆顶端的运动边界条件进行输入。与传统RAO方法相比,该方法充分考虑了铺缆船与电缆间的相互影响,可模拟实际海况中铺缆船施工时电缆的张力和曲率动态响应。分别采用该耦合模型方法和RAO方法计算铺缆船系统的动态响应,结果表明,RAO计算方法低估的电缆张力达9.9%。使用耦合模型方法分别建立八点系泊和四点系泊数值模型,比较了这两种系泊方案下海底电缆的动力响应,结果表明,四点系泊系统的电缆最大张力比八点系泊系统大15.9%,但二者都远小于最大允许张力。

Ship model resistance experiment of Qifan No.9 cable laying vessel is conducted and the ship resistance coefficient is obtained.In order to define its wave load,hydrodynamic analysis is carried out in software AQWA and corresponding parameters are obtained by calculating the vessel hydrodynamic model.Based above calculated results,the dynamic analysis for laying process of submarine cable is established by the dynamic analysis software OrcaFlex to obtain the dynamic responses of submarine cable in practical engineering.Compared with traditional RAO method,the method proposed above considers the interaction between cable laying vessel and cable,and can simulate the dynamic response of tension and curvature of cable during construction stage in actual sea states.The coupled model method and RAO method are used to calculate the dynamic response of the cable laying vessel system,and the results show that the RAO method underestimated the cable tension by 9.9%.Eight-point mooring and four-point mooring are adopted in the numerical model to make comparison of dynamic responses of submarine cable between these two methods.The results show that the maximum tension under four-point mooring system is 15.9%larger than that under eight-point mooring system but they are all far less than the maximum allowable tension.