碩士 / 國立臺灣海洋大學 / 河海工程學系 / 97 / In recent years climate change caused by unusual sea-level elevation and increasing the frequency of typhoons, it threatens the safety of marine construction projects. The past studies of seabed liquefaction potential are mostly related to a deterministic analysis. When the main considering wave force is greater than the sea-bed sand soil, the sea-bed soil liquefaction occurred. On the contrary will not be liquefied, however, in this case the sea-bed of sand liquefaction is still possible. In order to understand the role of a variety of sea bed wave power of the statistical characteristics of liquefaction, this study was adopted by the Land Application of reliability analysis to assess the probability of soil liquefaction process, combined with statistics on the log-normal distribution to establishment of wave induced sea-bed sand liquefaction probability model.
In this study, the wave height’s random characteristic on behalf of the variability of wave induced cyclic shear stress is used. Based on dynamic test of sea-bed liquefaction analysis of sea-bed sand soil liquefaction resistance, the difference of wave force between theory value and Hydraulic model test is also discussed. By the statistical analysis of results showed that the same conditions and test results into the Land of the assessment formula, it found that about 50% to 80% of the difference in coefficient of variability of sea-bed of sand is smaller than Land assessment formula. To explore the main reason is that most laboratories that may be liquefied sand seabed conditions tested, thus the scope of information resulting in smaller differences.
On the hand, comparing the past to evaluate the potential of sea-bed liquefaction and liquefaction probability of difference represented by the reason, related researchers are in the past as a small wave amplitude theory outside the main consideration, so the main reason for the sea-bed soil liquefaction resistance different than the definition. In addition to the relative density, soil depth and wave period can also cause to the consideration of differences in the causes of liquefaction probability. Finally, this study using the 『Tai Tam Taichung Harbor to the laying of gas pipeline』case analysis found that the path of buried pipeline, the segment off the coast of Hsinchu, Miaoli near Taichung Harbor and coastal waters there have a higher probability of liquefaction. According to the design return cycle of the 50-year assessment of the typhoon wave conditions, in Shanghai pipeline path between bed sand liquefaction rate of 7.24% ~ 13.89%.
In this study, try to apply wave analysis and dynamic test results to establishment of wave induced sea-bed sand liquefaction probability model. Combined with the specific wave parameters by statistical probability could be obtained the liquefaction probability of sea-bed sand. In the future, it could be supported by risk assessment analysis, will be able to help to ensure the safety assessment of the marine engineer.
| Identifer | oai:union.ndltd.org:TW/097NTOU5192043 |
| Date | January 2009 |
| Creators | Pei-Chi Tsai, 蔡培祺 |
| Contributors | Lien-Kwei Chien, 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 | 182 |
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