碩士 / 國立成功大學 / 水利及海洋工程學系專班 / 91 / This study is intended to probe the behaviour of sand dispersion in beach nourishment; the results may be useful for design and construction of marine works. A composite model of tidal current and concentration dispersion is employed to simulate beach nourishment with various placing locations, quantities, times and particle diameters of sand. To point placing case, the study outlines that the sand concentratuon is dispersed forward to offshore becoming stable after 24 hours of continue dumping, but varied with the distance and the difference of ebb or flood current. Nevertheless, the dispersion continues to growth along the long shore direction. If the sand placing quantity was designed to be a constant value, the instant placing disperses to far area than continuous placing.
While the sand is dumped in the near-shore area between breakwaters of An-ping Fishing Port and An-ping Commercial Port, the sand concentration could affect wider areas when the placing location gets farther away from the coastal line. Secondly, the closer to the shore the placing location is, the faster the dispersion occurs after sand placing is stopped, and the high sand concentration is bonded within these two breakwaters and will not pass through the southern breakwater line of An-ping Commercial Port even in flood. However, if sand is placed near the outside of southern breakwater of An-ping Commercial Port, wider areas of dispersion would appear and sand concentration would disperse offshore because of the sheltering of the breakwater. Moreover, when the sand placing location gets farther away from the southern breakwater, sand concentration disperses more widely along the long shore direction, but the variation in the cross direction approaches to a constant value. Finally, the particle size also affects dispersion clearly. The finer the sand particle is, the wider the dispersion area is; and high concentration influences longer because the sedimentation of fine sand particles takes a longer time. In this study the medium diameter is taken as 0.25 mm, and the concentration at the center of sand placing area is reduced to 1,000PPM after 4 days of sand placed. It is concluded that the successful design of beach nourishment project depends on the placing location, the coastal facilities such as groins, detached breakwaters and submerged breakwaters as well as sea climate for the shortage of sediments resources.
| Identifer | oai:union.ndltd.org:TW/091NCKU5083003 |
| Date | January 2002 |
| Creators | Ying-Feng Chung, 鍾英鳳 |
| Contributors | Tai-Wen Hsu, Ching-Jer Huang, 許泰文, 黃清哲 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 55 |
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