碩士 / 國立成功大學 / 水利及海洋工程學系 / 89 / Abstract
In this thesis, a fine sandy seabed in laboratory water tank ( d50 = 0.069 mm ) is used to investigate relationships between soil fluidization responses and overall suspended sediment concentration profiles, due to monochromatic wave and linear wave group. In the experiment setup, 5 optical sediment concentration probes with equal vertical intervals above a sandy bed, and 5 pore pressure transducers inside the sandbed are installed for simultaneous measurements. Comparisons with previous experimental studies show that under monochromatic wave and linear wave group loadings, the sandy seabed display also typical responses such as unfluidized, initially fluidized and continuously fluidized, respectively. In the unfluidized responses, zero pore pressure build-ups imply non-occurrence of the surface layer fluidization, as found in other silty tests and larger boundary layers. In addition, a resonance mechanism can be identified on initially fluidized responses, closely associated with permeability of the soils and wave steepness. It is also found that soils with lower permeability and under waves with steepness between 0.033 and 0.042 are likely to be fluidized in the first run. During the fluidization, our measurements show that the suspended sediment concentration increases significantly, especially at about 1 centimeter above the seabed. In general, vertical suspended sediment concentration approximate a logarithmic law for unfluidized responses, and a power law for fluidized under the same wave condition. It is suggested that measurements of near bed flow velocity fields on fluidization and under irregular waves in the further experiments may quantify sediment transport rates better.
| Identifer | oai:union.ndltd.org:TW/089NCKU0083045 |
| Date | January 2001 |
| Creators | de-shen chchien, 簡德深 |
| Contributors | Shan-Hwei Ou, Shiaw-Yih Tzang, 歐善惠, 臧效義 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 110 |
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