碩士 / 國立海洋大學 / 河海工程學系 / 90 / Generally speaking, the significant external forces that influence the safety of constructions in the near shore areas are earthquake force and wave force. This research aimed at the wave force and its influences on the seabed soil. The seabed soil’s pore water pressure accumulated and the effect stress decreased under the repeated wave force. When the pore water pressure reaches to a certain level will reduce the strength or cause liquefaction of the seabed soil. Liquefaction of the seabed soil will cause damage to seabed’s stability and may induce drifting sands, erosions, hollows and leads to leaning, sinking and destruction of the nearshore structures.
This research gathered environmental data of northeast Taiwan sea area and other related documents such as the wave period, the physical characters of the soil, the pore water pressure, the liquefactions of seabed and the stress of seabed surface under wave’s influences etc. and do thorough research of instabilities or liquefactions of seabed soil under wave’s influences. To ascertain different scholars’ divided theories of saturated soil liquefaction under periods of repeated external force, this research selected sand soil from Toucheng Cable Station, Tou-Cheng Yi-Lan, northeast coast of Taiwan, as the experimental samples; used moist tamping (MT) method, and self-studied three-axis power experiment system, which simulated the external forces sent down to the seabed from the wave; and considered of samples under different conditions, experimented with different external force acting periods (1、5、9、12 seconds), covered soil thicknesses (30kPa, 50 kPa) and related soil densities (35%, 55%), then, investigated the characteristics of soil excited pore water pressure as the scholars.
This research didn’t only ascertain the divided theory but also introduce different standards of seabed soil liquefaction evaluation methods by Nataraja & Gill (1983), Ishihara & Yamazaki (1984) and Jing-Wen Chen & Chao-Jin Yang (1996) and their evolvement, then compared and analyzed these three evaluation methods’ advantages and defects to be the reference resources revising the seabed liquefaction evaluation methods.
Furthermore, this research leaded in the influential elements of the near shore water depth and land shape that most scholars didn’t take in to consideration yet. By using the Near Shore Spectrum Wave Model (NSW) , we may analyze the distribution of wave height influenced by the land shape under a certain season’s wave period and lead in the experiment’s results, seabed sand’s cyclic shear stress strength ratio under actual periods of wave force then evolve a more complete, more practical and more accurate seabed soil liquefaction evaluation methods. And put it into use of the liquefaction evaluation around Lanyang plain to seek the liquefaction depth and range of the seabed.
| Identifer | oai:union.ndltd.org:TW/090NTOU0192029 |
| Date | January 2002 |
| Creators | Chang, Yao - Xian, 張燿顯 |
| Contributors | Chien, Lien-Kwei, 簡連貴 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 280 |
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