Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/13101
標題: 複合式出流口滯洪壩之水理特性初步研究
Preliminary Study on Hydraulic Characteristics of Detention Dam with Compound Outlet
作者: 陳薔諾
Chen, Chyang-Nuoh
關鍵字: detentuon dam with compound outlet;複合式出流口滯洪壩;peak attenuation;洪峰消減
出版社: 土木工程學系
摘要: 
滯洪壩可有效降低洪峰流量、控制流心及調節泥砂流出量,常設置於集
水區山地河川之中下游。不同出流口型式之滯洪壩,應有不同的滯洪、
排砂效應及滯洪容積。本研究採複合式出流口滯洪壩進行試驗研究,
因開口設計係屬上窄下寬佈置,除能儘速排除洪峰到達前之逕流量,
亦可加速滯洪池內淤砂的排出,增加池內淨空間,增加其對大流量之
洪峰消減。本研究運用室內渠槽試驗方式製造不同型態之入流歷線,
針對不同梯形斷面底寬佈置下之出流口流量公式、滯洪及排砂效應
分析探討,獲致下列初步成果:
1. 經理論推導與實驗分析,本研究提出複合式出流口流量公式,
並繪製流量水深關係圖,以供參考應用。
2. 洪峰消減度與入流歷線型態及滯洪壩出流口型式、
尺度有極密切關係。同時,驗證了此型式之出流口於小流量時,
可藉由寬底梯形斷面將水排出,增加池內淨空間,
大流量時可增加其洪峰消減的能力。
3. 就工程規劃設計而言,以三角形入、出流量歷線來分析較為簡易。
本研究獲致複合式出流口設置之無因次最小滯洪容積
約為矩形者之75﹪。
4.排砂效率Ω其與相對入流歷線基期時間成指數函數關係,
且與歷線時程有密切關係,亦與歷線分佈型態之特徵值α有關,
而以α愈小者愈加顯著。
5. 以排砂率η來探討排砂特性,本文以尖峰流量Qim、
出流口型式m為參數,提出經驗模式。

The purposes of using detention dams in a stream are to reduce
peakflows, to
control flow direction, and to regulate sediment discharge.
Detention dams
are usually constructed in the mid- and lower section of a
stream. The forms
of discharge outlets affect not only the detention efficiency
and sediment
flushing efficiency, but also the detention volume. Compound
outlet detention
dams are used in this study. The outlets consist of various
combinations of
rectangular and trapezoid openings, with rectangular openings on
top and
trapezoid openings at the bottom. These special arrangements
allow a rapid
discharge prior to the arrival of peak flows as well as the
sediment thus
leave greater capacity to house the incoming sediment. All
experiments were
carried out in an indoor hydraulics laboratory. Selected forms
of inflow
hydrographs were fed to the scaled detention models. Discharge,
flow
detention, as well as sediment flushing efficiency under
different compound
outlets were monitored. The results of the study are outlined as
follows:
1. Discharge formulas from different compound outlets are
obtained through
theoretical and experiment analyses. A graphical relationship
between
discharge and flow depth is presented.
2. The peak flow reduction is found to be highly related to the
inflow
hydrographs, the forms and the scales of outlets. In addition,
the
arrangement that the trapezoid opening located at the bottom of
the opening
is proved to be efficient in discharging the inflow when the
flow rates are
small. The trapezoid openings were also effective in reducing
peak flows
during large inflow stages.
3. Simple triangle in- and out-flow hydrographs are the easiest
cases to
analyze from the viewpoint of engineering designs. A
dimensionless equation
of the minimum detention volume is obtained from the study. The
detention
volume was 25% less compared to that of the rectangular
openings.
4. Sediment flushing efficiency is found to be exponentially
related to the
relative inflow base time (). It is also highly related to the
time and the
rising segment of hydrograph. The smaller the eigenvalue of the
distribution
of the inflow hydrograph (α), the higher the correlation.
5. An empirical equation is obtained to describe the sediment
flushing rate
in terms of the peak flow (Qim) and the outlet form parameter
(m).
URI: http://hdl.handle.net/11455/13101
Appears in Collections:土木工程學系所

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