Experimental Studies on Engineering Properties of Horizontal Fine Sandy Seabeds in Nearshore Waters

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Project title

Code/計畫編號

NSC91-2611-E019-011

Translated Name/計畫中文名

近岸水平細砂質海床工程性質之試驗研究

Project Coordinator/計畫主持人

Shiaw-Yih Tzang

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

歐善惠

Department/Unit

Department of Harbor and River Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=753925

Year

2002

Start date/計畫起

01-08-2002

Expected Completion/計畫迄

01-07-2003

Bugetid/研究經費

846千元

ResearchField/研究領域

土木水利工程

本研究應用斷面造波水槽以規則波進行試驗研究，探討水深45、35及 25cm時底床液化反應對近底床處速度場之影響。試驗材料採用中值粒徑 d50=0.073mm的細砂質土壤，試驗量測項目包括單點流速、不同深度剖面的孔隙水壓及懸浮漂砂濃度。由代表性試次結果發現起始液化反應時，水平方向流速會隨平均孔隙水壓抬升而逐漸變小，可最多較起始值小約 50% 左右；相反地，垂直方向流速隨孔隙水壓階段抬升也階段性變大，甚至有 5 倍以上之變化。隨著液化次數增加，水平和垂直方向速度分量之縮小和放大的量亦會隨之慢慢減少，最後再呈現非液化反應的特性。 In this paper, we applied regular waves in a laboratory flume to study the effects of the fluidized seabed responses on the near above velocity fields with water depths of 45, 35 and 25 cm, respectively. The test soil is of a fine sandy type with a d50 of 0.073 mm and the measurements consist of time series of one-point velocity, depth profiles of pore pressures and suspended sediment concentrations. From several typical data, the analyzed results generally show that above an initially fluidized seabed during the build-up of mean pore pressure the amplitudes of horizontal velocity component gradually decrease even by a maximum of about 50% compared with the initial values. Meanwhile the vertical velocity components increase sharply at each stepping pressure building-up phase to be more than 5 times larger. The trends of the magnitude changes would become less significant after more continually fluidized runs and gradually displayed similar characteristics to those of an unfluidized response.

Keyword(s)

流速場
液化海床
規則波
傳輸
Velocity field
Fluidized seabed
Regular wave
Sediment transform

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Experimental Studies on Engineering Properties of Horizontal Fine Sandy Seabeds in Nearshore Waters

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