海底多跨悬空输流管道流-固-土多场耦合机理及涡激振动特性研究

The bottom topography of deep sea is complex and highly variable, there is a lot of undulating terrain areas, and this causes the pipelines to have multiple spans. These free spans may experience Vortex-Induced Vibrations (VIV) when subjected to ocean current, which may lead to unacceptable accumulation of fatigue damage. Although, the VIV of single span pipelines has been thoroughly investigated for decades, few studies have been done on the VIV of multi-span pipelines. Each span may not be considered individually, but rather the entire system of spans must be analyzed as a unit. The pipe-soil interaction is complicated in shoulders，several vibration modes can become active, neighbor spans may interact dynamically. Up till now, the knowledge and guidelines are inadequate for satisfying the demand of ocean engineering under deep sea condition. This research project will investigate the Fluid-Structure-Soil interaction mechanism and VIV of multi-span pipeline conveying fluid mainly by experiment investigation, supplemented by theory analysis and numerical simulation. The pipe-soil interaction model will be built. The influence of internal fluid on VIV will be studied. The pure In-Line VIV of multi-span pipelines will be analyzed. The coupling between In-Line and Cross-Flow VIV will be illustrated. The interaction between adjacent spans will be discussed. The main aim of this research project is to supply the theory knowledge and engineering methods for pipeline vibration control and design.

深海海底地形复杂多变，存在大量地势起伏区域，管道铺设不可避免的会出现多段悬跨，由此引发的悬跨段涡激振动会导致结构严重疲劳损伤。长期以来，人们更多地关注单跨管道涡激振动问题，缺乏对多跨管道涡激振动方面的深入研究。多跨管道并非多个单跨管道的简单累加，其跨肩处管-土作用十分复杂，涡激振动常呈现多模态，相邻管跨彼此制约影响，现阶段，学术界对相关问题的认识水平还无法满足深海工程实际需求。本项目拟定开展海底多跨悬空输流管道流-固-土多场耦合机理及涡激振动特性研究，运用实验观测、辅以理论分析和数值模拟等手段，构建跨肩处管-土相互作用模型，分析内流和跨肩土体对多跨管道涡激振动的影响，讨论多跨管道纯顺流向涡激振动特性，探寻顺流向与横流向涡激振动的耦合机制，建立相邻管跨之间相互影响的判定准则，为深海海底管道设计和振动控制提供必要的理论支持和工程实用方法。

海底管道是深海油气开采输运不可或缺的关键设备之一，被誉为“海洋油气生命线”。由于深海海底地形复杂，管道铺设难度大、费用高，实际工程中的管道常直接铺设于起伏的海床表面，不做任何掩埋处理，加之海流冲刷作用，形成较长悬跨和多段悬跨的现象十分普遍。悬跨段的涡激振动(VIV)是导致结构损伤失效的重要诱因。海底悬跨管道涡激振动是一个海流、管道与跨肩处海床土体之间相互作用的流-固-土多场耦合问题，涉及多个领域、多个层面，目前大量相关基本理论认识尚不清晰。. 本项目的开展旨在破解多跨悬空输流管道VIV方面的相关科学难题，以深海海底多跨悬空输流管道为研究对象，通过实验研究、理论分析和数值模拟等多种研究手段，探究了跨肩处的管-土耦合作用机制，构建了多跨管道流-固-土多场耦合的预报模型，揭示了内部输运流体、跨肩管土作用、轴向力等对悬跨管道VIV的影响规律，研究了倾斜柔性圆柱涡激振动特性及其抑制措施等。. 经过四年的系统深入研究，取得了一系列理论层面和技术层面的突破，授权发明专利16项，发表学术期刊论文37篇(其中SCI检索21篇，EI检索期刊14篇)；相关研究成果得到了国内外学者的广泛认可，能够为海洋管道的工程设计及振动控制提供必要的理论保障，具有重要的理论价值和工程意义。