海底管跨涡激振动疲劳可靠性研究

Reliability research on fatigue caused by vortex induced vibration of submarine pipeline span

本文考虑波浪水质点与管线振动间的相对运动速度以及波浪和海流的联合作用,对传统的波浪载荷计算方法进行了改进,引入了波浪激励载荷中的二阶平方阻尼项,从而建立了管跨段的非线性涡激振动方程。通过较为合理的化简,将非线性随机振动方程化为相应的线性随机振动方程。利用谱分析解法,由波浪谱推得海底管线的波浪力谱,作为振动方程的输入谱,计算得到相应的输出谱,进而确定位移和应变等各种响应随机过程的概率分布,最后结合可靠性分析理论确定管线的疲劳失效概率。

Considering both relative motion of water particle of wave and vibration of span and coefficiencies of wave and sea current,an improved calculation method of wave force is offered in this paper.Due to the introduction of second-order square damp term in wave force,the nonlinear vortex induced vibration equation of pipeline span is set up.On analyzing fatigue invalidation reliability of pipeline span,a corresponding linear equation is derived from nonlinearit.The above equation is solved by spectrum analysis method,which employs the wave force spectrum derived from wave spectrum to deduce the output spectrum and further ascertain the probability distribution of strain responding stochastic processes.Finally,the fatigue invalidation probability of pipelines is figured out by combining reliability analysis theory.