| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 101 === In recent years, Taiwan is attacked by typhoons and flood, causing severe local scour on riverbed, resulting in the bridge foundation is exposed and the foundations embedment depth is insufficient. If we can not effectively maintain bridge safety, it will seriously affect the livelihood and economic and life safety. Local scour depth represent a significant factor for the bridge foundation stability, in which Flow velocity is one of the most important parameters for assessing local scour, Flow velocity effect the strength of flow force which action on the bridge pier foundation. The purpose of this study is to research a method of flow velocity measurement which can use during flood and it will not be affected by adverse environmental impact and cost-effective. The principle for use cable connected to the plumb into the water and it will be a balance relations between flow drag force and buoyancy, plumb dead weight, and the cable tension. Through flow drag force for the plumb to produce a swing angle to estimate velocity. In the critical Reynolds, drag coefficient used in this study is not a constant value number ,which must be correct. While the balance relationship must join the cables effect. Therefore, this study introduces a numerical method of piecewise extrapolating to a more detailed analysis for the method of measuring the velocity using the cable drag plumb.
Keyword：flow velocity measurement, flow drag force, cable and plumb, piecewise extrapolating method
|
|---|
