【作者】 吕海青；

【导师】 李三忠； 庄振业；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2006， 硕士

【摘要】 陆架水流塑造底沙形成各种海底地貌形态,基本顺水流方向发育的砂质底形称为水下沙脊,垂直于主水流方向的丘状底形称为沙波。后者是砂质海底最常见的底形地貌,它的迁移和运动可以淘空或掩埋海底管线,导致建筑物基础失稳,同时它也可以标志海洋环境的变化。沙波沙脊与海洋工程、航运乃至军事都有着密切的关系,所以引起国内外很多专家学者的兴趣。本文所研究的扬子浅滩位于内陆架外缘长江口东侧30.7o～32.6oN、122.5o～125oE处,水深30～50米,总面积约3万km2。本文主要使用近期两次管线调查资料,参考了各单位在扬子浅滩所做的六次调查报告和部分论文编写而成。本区沙波的移动与水文、地质条件有密切关系,在常态海况下沙波可以在潮流动力下移动,但是较大移动却是由台风或者寒潮等引起的。参考2000年两次管线调查资料,统计了该区32个观测点的沙波参数,得出沙波的运动方向主要集中在90o—180o。由于定位观测实施比较困难,费时费力,因此通过搜集该区的底质、潮流和台风等资料,采用不同水文公式进行计算的方法,分别得出常态海况下和暴风浪时期沙波的移动距离。两公式采用的参数不同,得出的结果也有差异。Rubin公式得出的结果比筱厚-椿东一郎公式略大。但两个公式得出的结果上都说明在常态海况下沙波每年的迁移距离较小,在暴风浪期间位移较大。为了对比,还用相同的水文公式计算了东方岸外东区沙波的迁移速率,也得出类似的结果。通过水文公式计算的结果得知,暴风浪对沙波移动的影响较大。这说明由暴风浪等引起的强底流是沙波较大距离迁移的主要动力。更多还原

【Abstract】 The continental currents can make the sea bottom sand to all kinds of seabed forms. The seabed form,which grows paralled to the main current,is called the submarine current ridges,and sand dunes or sand waves,which are developed vertical to the main current. The sand dunes are the typical forms on the sand seabed. The migration and movement of sand dunes can empty the sand overlaying the pipes or bury the pipes leading to the base destabilization of building,and are the marks of the sea environmental changes. The current ridges and sand waves have closed relationship with the marine engineering,navigation and military affairs,so they have been a major research focus in geosciences.The study area is located in the east of changjiangriver in East China Sea(30.7o～32.6oN、122.5o～125oE),which water deep 30~50m and an area of 3×104sqmeters.By the six investigate reports about the study area and partially pressed papers,we can know that the motion of sand waves in Yangzi Shoal have the closed relationship with the hydrology and geology of the area. In usual day,sand waves can be drived by the tidal current,which derection is consistent with the major tidal current orientation. However,the bigger and harmed move distance of sand waves is aroused by the typhoon or cold waves. By the collect of hydrology and typhoon data and calculation of mathematics fomula,we gained the move distance of sand waves in the usual day and typhoon. Because orientation observation is difficult,so by the collect of sediment grain、tidal current and typhoon data,we made use of the different hydrological fomulas and drew the conclution about the distance in the usual and typhoon state. Because the two formulas used the different parameters,the conclusions is different.However,both of the formulas’s results can explain that the distance of sand waves in ususl states is small than in the typhoon states.At the same time,we also calculate the transfer velocity of the sand waves’in the Dongfang of South Sea,and we also drew the similar conclusions In typhoon or cold wave states sand waves can transfer bigger distance. This show that the primary factor which can induce the sand waves’transference is typhoon or cold waves.更多还原