南海北部外陆架海底沙波迁移特征及其动力机制研究

Submarine sand waves, vital to seabed stability, are an important consideration for oceanic engineering projects such as oil pipe lines and submarine cables. In this project, taking the outer shelf of the Northern South China Sea as the target area, the migration rule and dynamic mechanism of the submarine sand waves will be studied. Based on the geological environment conditions such as the particle size of the surface sediment, the distribution and migration data of the sand waves in the study area, combined with the high precision bottom flow field data simulated by the Regional Ocean Model System (ROMS), the typhoon impact on migration of submarine sand waves will be studied. Meanwhile, the impact of internal wave will be studied, too. According to the simulation results, we will put forward a numerical model applicable to the simulation of sand wave migration in the Northern South China Sea. The assessment system of typhoon-sand waves and internal wave-sand waves will be studied based on this model, which will provide essential technical support for the assessment of the stability of the submarine pipeline of Liwan 3-1 in Northern South China Sea.

海底沙波稳定性对海底管道等海底设施的安全性具有非常重要的影响。本项目以我国南海北部外陆架海底沙波分布区为目标区，开展海底沙波迁移特征及其动力机制研究。利用研究区已有的表层沉积物粒度、海底沙波的分布及迁移等地质环境条件，结合ROMS模型模拟的高分辨率底流资料，定量分析台风对海底沙波迁移的影响，定性分析内波在海底沙波迁移中的作用，初步构建一套适用于我国南海北部外陆架海底沙波运移的数值模式，形成台风和内波对海底沙波迁移影响的评价体系。为我国南海北部荔湾3-1气田等海底管道安全评价提供技术指导。

海底沙波稳定性对海底管道等海底设施的安全性具有非常重要的影响。本项目以我国南海北部外陆架海底沙波分布区为目标区，开展了海底沙波迁移特征及其动力机制研究。本项目利用研究区已有的表层沉积物粒度、海底沙波的分布及迁移等地质环境条件，结合ROMS模型模拟的高分辨率底流资料，定量分析了台风对海底沙波迁移的影响，定性分析了内波在海底沙波迁移中的作用，初步了构建一套适用于我国南海北部外陆架海底沙波运移的数值模式。利用该方法对研究区内海底沙波运移方向的计算结果和搜集所得资料比较吻合，均为向东向南方向；不同站点的迁移距离在0-21.8m之间，且为往复累积的结果。模拟计算了研究区内两个站位在“凡亚比”台风影响期间的迁移距离，说明台风过境能对海底沙波的迁移产生重大的影响。台风过境及内孤立波导致的南海北部的底层强流是南海北部海底沙波运移的主要动力来源。本研究为我国南海北部荔湾3-1气田等海底管道安全评价提供技术指导。