波浪力作用下海洋钻井隔水管随机振动研究

随着海洋钻井向深水海域发展 ,隔水管的受力状态更加复杂。特别是在随机载荷波浪力的作用下 ,隔水管会发生十分复杂的随机振动 ,从而偏离原来的铅垂位置 ,严重时可使钻具受到破坏 ,引起钻井中断。应用随机振动的理论和方法 ,分析了波浪力的随机过程和随机模型 ,指出波浪力是一个均值为零的平稳随机过程 ,隔水管的横向随机位移也是一个均值为零的平稳随机过程。采用模态分析的离散化方法导出了隔水管横向随机振动位移相关函数和均方位移的计算公式 ,编制了计算程序 ,分析了风速对隔水管横向随机振动均方位移的影响。算例表明 :当风速小于 10m/s时 ,均方根值很小 ,可以不予考虑 ;当风速大于 2 0m/s时 ,均方根值与风速成近似的线性关系。本文结果可为隔水管的随机响应计算和工程设计提供一定的理论参考作用。

On Random Vibration of Riser System in Marine Drilling Subjected to Wave Force

With the development of drilling in deep sea,the forces of riser system are more complicated. Especially,random vibration and offset of riser system in marine drilling under the random wave force,if terrible,may cause failure of drilling tools and break-off of drilling. By using the random vibration theory,the random process and random model of wave force are analysed. Wave force is a stationary random process and its mean is zero. Transverse displacement of riser system in marine drilling is also a stationary random process and its mean is zero. The transverse random vibration of riser system is investigated by means of mode analysis and the general formulas for its correlation funtion and mean square response are derived. The computing program is performed,the effect of wind speed on the transverse mean square response of riser system is investigated. The numerical example shows that when wind speed is less than 10 m/s,the root of mean square is very small,and it may be neglected; when wind speed is more than 20 m/s,the root of mean square is approximately linear with wind speed.