北部湾东南海域海底沙波沙脊区沉积物输运的数值模拟研究

IOCAS-IR > 海洋地质与环境重点实验室

	北部湾东南海域海底沙波沙脊区沉积物输运的数值模拟研究
其他题名	Numerical Simulation on Sediment Transportation in Sand Waves and sand ridges field in the Southeast of Beibu Gulf
	郭立
学位类型	硕士
导师	阎军
	2017-05-23
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	海洋地质学
关键词	北部湾沙波沙脊数值模拟 Delft3d
摘要	沙波和沙脊是陆架上常见的地形地貌，广泛分布于潮控陆架环境中。北部湾东南海域海底发育大量沙波和沙脊，由于海底沙波不是静止不动的，其垂向生长或横向迁移将对海底工程设施、海岸环境、航道安全等造成潜在威胁，因此，对沙波和沙脊形态特征、分布及迁移演化规律的研究具有重要的工程意义。本文采用数值模拟的方法，建立了北部湾高精度（200m）三维数学模型，模拟了北部湾的流场。同时，基于课题组在本区多年的多波束、旁扫声纳和浅地层数据以及实测波流数据和获得的表层沉积物及水体悬浮物资料的数据积累，总结了北部湾东南海域海底沙波的分布特征及控制因素，为海底沙波演化的数值研究提供验证资料。通过分析模拟的流场特征和地形地貌的关系，得到以下认识：（1）研究区近底层的流速多为北偏东或南偏西方向的往复流，流速多分布在20-90cm/s。（2）沙脊走向发生变化及两侧沙波倾向不同的原因在于沙脊两侧最大涨落潮流流速的差异。研究区流速受沙脊影响较大，沙脊的阻挡限制了流速，流速又反过来影响了沙脊的演化。潮流通道及流速的分布情况与沙波形态、规模的差异性分布一致。（3）底床平均剪切应力分布和地形密切相关，与沉积物粒径等值线分布格局一致，低应力区对应于粘土质粉砂等细颗粒沉积物，高应力区对应砾质砂、粉砂质砾等颗粒较粗的沉积物区域。（4）底床剪切应力矢量分布与实测沙波迁移方向大体一致。（5）此外，研究区出现有近对称形态的沙波，可能为海平面变化期间多期潮流共同作用形成的残余沙波。
其他摘要	Sand waves and sand ridges are widely distributed on the tidal shelf. As the sand waves are not stable, their vertical growth or lateral migration could be a potential threat for the submarine engineering facilities, which are also important for the management of navigation and coastal environment. Therefore, it is of great significance to explore the morphology, distribution, and migration of sand waves and sand ridges. A large number of sand waves and sand ridges exist in the southeast of Beibu Gulf. Here, a three dimensional mathematical model with high resolution(up to 200m) is established to simulate flows and bottom shear forces in Beibu Gulf. Based on the multi-beam, side scan sonar, sub-bottom profile data and surface sediment, we analyze the morphology, distribution, and migration of sand waves in the southeast of Beibu Gulf. These results are compared with the modelled flows and shear forces to validate the results of numerical simulation. By analyzing the relationship between the simulated flows and the topography, we found that: (1) Flows near the bottom are reversing in the tidal cycle, whose direction is mostly northeast or southward, and the flow velocity is between 20 cm/s and 90cm/s. (2) Flow magnitude and distribution are mainly affected by the sand ridges, consistent with the distribution and migration of sand waves. Such flows can also affect the evolution of the sand ridges. (3) The distribution of average shear stress on the seabed is closely related to the characters of terrain and sediment. The low stress region corresponds to fine sediment such as clayey silt, while the high stress area corresponds to gravel sand and silt gravel and other coarse sediment areas. (4)The direction of shear stress on the seabed is in agreement with the measured sand migration direction. (5)Some symmetrical sand waves have beddings with opposite inclinations, which are possibly caused by the various hydrodynamics in different periods during the sea level changes.
学科领域	海洋地质学
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/136650
专题	海洋地质与环境重点实验室
作者单位	中国科学院海洋研究所
第一作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	郭立. 北部湾东南海域海底沙波沙脊区沉积物输运的数值模拟研究[D]. 北京. 中国科学院大学,2017.

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文件名称/大小	文献类型	版本类型	开放类型	使用许可
毕业论文郭立 0608.pdf（5160KB）	学位论文		限制开放	CC BY-NC-SA	浏览