碩士 / 國立中山大學 / 海洋環境及工程學系研究所 / 107 / Seafloor investigation was conducted at a restricted coastal area near Gushan Fish Market by a mechanical scanning sonar system. The objective of this investigation included seafloor mapping, underwater proud objects detection (i.e., position, dimensions and features) and sediment evaluation. Based on these information, detailed assessments of seafloor characteristics and engineering behavior were conducted in this specific area.
A total of 61 underwater proud objects were detected and listed, which include 21 round shaped objects, 11 line shaped objects, 6 rectangular shaped objects, 3 large blocky structured objects (about 6 m in length), and 20 irregular shaped objects. According to the characteristics of these proud objects, which include position, functionality and degree of human intervention, they were classified into three categories, i.e., “dropped objects”, “discarded objects”, and “deployed objects”.
The seafloor composed of silty sediments was flat. Scour features were detected at specific areas, including about 3.5 and 5 m in width at west and east corner of Gushan Fish Market, and 11 m in width at Xinbin Pire. Base on the hydrodynamic theory, the sediment transport is mainly controlled by tidal current and location of pier structure.
In addition, typhoon can have prominent effects on sediment transport. Base on limited data, an area of scouring phenomena was enlarged to 4 times after the passage of a moderate scaled typhoon.
The pier wall of Gushan Fish Market was intact, which illustrated that local scouring effects caused only limited influence on the pier structure of Gushan Fish Market. The discontinuous pier structure, the large blocky structures and the local scour features indicated that Xinbin Pire and Shaochuantou Park Pier were intended to be degraded by hydrodynamic influences.
The results of this investigation concluded that the mechanical scanning sonar system is effective in seafloor monitoring and evaluation at a restricted underwater construction site.
| Identifer | oai:union.ndltd.org:TW/107NSYS5282019 |
| Date | January 2019 |
| Creators | Shih-Jui Chen, 陳詩叡 |
| Contributors | Wen-Miin Tian, 田文敏 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 151 |
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