碩士 / 國立成功大學 / 水利及海洋工程學系碩博士班 / 93 / This thesis primarily investigates with flume experiments the interactions of regular waves and a rectangular permeable submerged obstacle on a fine sandy seabed. Experimental results illustrate that in unfluidized responses no settlement of submerged obstacle or bed-form changes occurred. In initially fluidized responses the settlements became very evident to depths of about average of 51 % of the fluidization depth decreasing downstream-wards. Meanwhile, seabed levels were also decreasing due to noticeable scouring and active sediment suspensions. Generally in continuously fluidized responses no more settlements were seen in cases with shallower fluidization depths. But seabed continues to be scoured during wave generations to lower bed depths downstream-wards until another unfluidized run.
The monochromatic wave tests further show that in unfluidized responses the wave reflection coefficient from the permeable submerged obstacle was 0.157 compared with 0.193 for impermeable cases, while wave oscillations at each site remained stable. As the submerged obstacle had been settling down into the fluidized seabed, the reflection coefficient gradually decreased to about 0.09. The wave energies also started to decay along the fluidized seabed with ratios up to as high as of 60 % and 52 % at a downstream site of the permeable and impermeable submerged obstacle, repectively. In particular, the decay ratio of wave energy was seen to decrease in a longer time (600 sec) run as excess pore pressures were decreasing. As a result, the installation of submerged obstacle can help seabed resist stronger waves while reduce possibilities of occurrences of bed fluidization.
| Identifer | oai:union.ndltd.org:TW/093NCKU5083019 |
| Date | January 2005 |
| Creators | Chao-Chung Chen, 鄭肇宗 |
| 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 | 112 |
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