畸形波作用下半潜平台运动响应研究

海洋结构物的水动力性能研究对于安全、经济的工程设计至关重要.近年来,由海浪巨大波浪引起的事故越来越多地见诸报道,因此,有必要深入研究波浪尤其是畸形波对结构物产生的载荷及运动响应.海上浮式平台的运动响应与系泊载荷密切相关,而文中的出发点正是研究在何种波浪条件下会引起平台的最大运动响应.通过对一座设计作业水深为500 m的半潜式平台进行频域计算,获得了平台在自由漂浮状态下的响应函数(RAO),并与实验数据进行了比较.通过时域模拟,获得了新年波和"三姐妹"波作用下的平台运动响应,研究了畸形波的存在对于平台运动的影响.此外,还研究了畸形波中最大波峰值及连续大波的出现间隔对平台垂荡和纵摇运动的影响,可为后续研究和工程设计提供参考.

Motion Behavior of a Semisubmersible in Freak Waves

The hydrodynamic performance of offshore structures is of great importance for achieving safe and economical designs. In the last few decades, an increasing number of reported accidents due to rough ocean waves call for in-depth investigations on the loads and motions of offshore struc-tures, particularly the effects of freak waves. This paper aims at determining the sea conditions that may cause the maximum motion responses of offshore structures, which have a significant effect on the loads of mooring systems because of their tight relationship. A frequency-domain analysis was con-ducted to obtain the response amplitude operators (RAOs) of a semisubmersible platform of 500 me-ters operating depth, comparing with the experimental data. The motion behaviors under the New Year Wave and a 'Three Sisters' wave sequence were investigated with time-domain simulations. There-after, a series of predetermined extreme wave sequences with different wave group characteristics, such as the maximum crest amplitude and the time lag between successive high waves, are adopted to calculate the hydrodynamic performance of the semisubmersible with mooring systems. The study shows that the maximum motion responses depend on the largest wave crest amplitudes and the time lags between successive giant waves. This paper provides an important reference for future designs which could consider the most dangerous wave environment.