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在中国南海东部百年一遇的台风海况下,考虑不同风载荷的计算方式,对某Classic-Spar平台及其系泊缆索的动力响应作了时域非线性数值模拟.首先将平台频域水动力结果变换到时域;然后运用非线性有限元方法计算张紧式系泊缆索的动张力特性;最后运用四阶龙格-库塔法在时间域内计算平台及其系泊系统的非线性耦合运动方程.分析结果表明:在时变风的作用下,平台运动不仅会偏离平衡位置,而且由于时变风的特征频率通常在Spar平台水平面运动的自振频率附近,因此相对于稳态风,考虑时变风的影响将会激起平台大幅度的水平面慢漂运动响应,从而诱发很大的系泊张力.
Under the condition of typhoon-sea once a year in the east of the South China Sea, the nonlinear dynamic response of a Classic-Spar platform and its mooring cable was numerically simulated considering different wind loads. Firstly, The results are transformed into the time domain. Then, the nonlinear finite element method is used to calculate the dynamic tension characteristics of tensioned mooring lines. Finally, the fourth order Runge-Kutta method is used to calculate the nonlinear coupling motion of the platform and its mooring system in the time domain The results show that the platform motion not only deviates from the equilibrium position under time-varying wind, but also because the characteristic frequency of the time-variant wind is usually near the natural frequency of the horizontal plane motion of the Spar platform. The effect of time-varying winds will arouse the platform’s large-scale horizontal drift motion response, thus inducing great mooring tension.