Research on Floating Body in Directional Spectrum Waves

在石油生产或海洋利用领域，如浮式机场，都需要稳定的浮式海上结构平台。为此，研究这种结构在定向谱波即实际的短峰不规则波中的行为具有重要意义。在本联合项目中，结合日本和巴西在海洋开发领域的情况，采用理论和实验两种方法研究了海上结构物在定向谱波中的行为。第一年在巴西进行现场观测，在日本横滨国立大学进行模型结构基础实验。第二年，开发了用奇异分布法估计海上半潜式结构水动力的程序代码。从安全的角度来看，本规范还考虑了大部分列出的条件。提出了一种简单的慢振荡估计方法。在最后一年，开发的代码通过与实验结果的对比得到了验证。为此，进行了大致列出的条件（约20度）的实验。此外，从钻井平台和大型浮式机场在定向频谱波中的行为角度进行了分析，明确了考虑弹性的必要性。

Stable platform by floating offshore structures are required in the fields of oil production or ocean utilization, for example floating airport. For this purpose, research on the behaviors of such structures in directional spectrum waves namely realistic short crested irregular waves is important.In this joint project, the behaviors of offshore structures in directional spectrum waves were investigated both by theoretical and experimental manner taking into account the situation of both Japan and Brasil in the field of ocean developement.In the first year, observation on the spot was carried out in Brasil, and the basic experiments of model structures were carried out in Yokohama National University (Japan).In the second year, a program code was developed for estimating hydrodynamic forces acting on semi-submersible offshore structures by the method of so called singularity distribution method. From the view point of safety, lrgely listed conditin was also considered in this code. Simple estimation method for slow oscillation was also developed.In the final year, developed code was confirmed by the comparison with experimental results. Experiments of largely listed condition (about twenty degrees) were conducted for this purpose.Furthermore, not only drilling rig but also long and huge floating airport was treated from the view point of its behaviores in directional spectrum waves and the necessity of considering elastisity was made clear.