动力学效应对沉船翻转作业吊缆安全性的影响

Influence of dynamics effect on safety of cable in wreck up-righting project

为了研究动力学效应对沉船翻转作业安全性的影响,将吊缆张力作为翻转作业安全性评估指标,假设船体翻转作业时起重臂吊点固定不动,研究区域水底为刚性底,不计上层建筑影响和建立沉船翻转准静态模型时只考虑回复力与外载荷,分别以船体质量、吊缆刚度、收缆速度与波浪载荷为变量,应用时域分析方法,计算了考虑动力学效应的吊缆张力,基于最大吊缆张力分析了沉船质量、吊缆刚度、收缆速度与波浪载荷对翻转作业中吊缆张力的影响,评估了沉船整船翻转作业的安全性。计算结果表明:在沉船船体翻转作业中,吊缆张力最大值将随沉船质量、吊缆刚度与收缆速度增大而增大,且吊缆张力最大值与收缆速度呈线性关系,与船体质量呈近似线性关系,与吊缆刚度呈非线性关系;当收缆速度由0.001m·s^(-1)增加至0.020m·s^(-1)时,吊缆张力最大值较初始值增量增大了约22倍,可见,在沉船翻转作业中,不可忽略动力学效应对作业安全性的影响。

In order to study the influence of dynamics effect on the safety of wreck up-righting project, cable tension was introduced as the evaluation index of the safety. Four hypotheses were made, including that the hanging point of lifting arm was be fixed, the seabed in research area was rigid, the effect of superstructure was ignored, and restoring force and external loads were only considered in establishing the quasi-static model of up-righting wreck. Cable tensions, ship weight, cable stiffness, cable-winded velocity and wave loads were taken as variables. Cable tensions in wreck up-righting project were calculated by using the time-domain analysis method while considering dynamics effect. Based on the maximum calculated cable tensions, the influences of ship weight, cable stiffness, cable-winded velocity and wave loads on cable tensions were analyzed, and the safety of up-righting project was evaluated. Calculation result shows that in wreck up-righting project, the maximum cable tension increases when ship weight, cable stiffness and cable-winded velocity increase, and has linear relationship with cable-winded velocity, approximate linear relationship with ship weight, and nonlinear relationship with cable stiffness. When cable-winded velocity increases from 0. 001 m·s^-1 to 0. 020 m·s^-1, the increment of the maximum cable tension increases by 22 times, so the dynamics effect cannot be ignored in the safety evaluation of wreck up-righting project. 7 tabs, 21 figs, 27 refs.