中文摘要：

针对我国南海内孤立波活动频繁的实际情况,建立了非均匀海流、表面波和内孤立波联合作用下钻井隔水管的准静态分析模型,并分别采用Airy线性波理论和两层流的Kd V理论计算表面波和下凹型内孤立波的速度和加速度,利用有限差分离散和LU分解法求解钻井隔水管的静态微分方程。方法验证结果表明,本文方法与其他文献结果吻合较好,具有较高的可靠性。实例分析结果表明,表面波和内孤立波分别在相位角为12°和0°时对隔水管的准静态性能影响最大;内孤立波使上层流体中隔水管的横向偏移、弯矩、Von Mises应力大幅增加;在内孤立波波谷对应深度附近,隔水管弯矩呈＂台阶状＂突变,剪力呈＂尖峰状＂突变;内孤立波振幅越大、上下两层海水密度差越大,内孤立波对隔水管受力与变形的影响越剧烈。建议加强我国南海各油气区内海洋内孤立波的监测和预测,更好地指导海上钻井隔水管安全作业。

英文摘要：

In view of frequent occurrence of internal solitary waves（ISW） in South China Sea,a quasi-static model is established to analyze a drilling riser under combined loads of non-uniform currents,surface waves（SW） and ISW.In this model,velocity and acceleration of SW and ISW are respectively calculated by the Airy＇s linear wave theory and Kd V theory of a two-layer flow. And then,a static differential equation for the riser is discretized by finite difference method and solved by LU decomposition method. Verification analysis shows that the results of this approach are well conforming with those in some other previous papers,and thus the quasi-static analysis has a good reliability.Cases studies indicate that the quasi-static performance of a drilling riser has a maximal response when the phase angles of SW and ISW are 12° and 0°. ISW makes the lateral deviation,bending moment and Von Mises stress of the riser increase significantly in the upper seawater layer. Around ISW trough,bending moment changes suddenly in a step-like jump,and shearing force alters sharply in a peak state. The larger the ISW amplitude and the greater the density differential between the two layers of seawater,the severer the impact of ISW on the stress and deformation of the drilling riser. Therefore,in order to guarantee a safer operation of the drilling riser,monitoring and prediction of ISW should be enhanced in every offshore oil and gas fields in South China Sea.