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Study on Discharge Capacity of Additional Spillway due to Increased Design Flood

Title
Study on Discharge Capacity of Additional Spillway due to Increased Design Flood
Author
이재홍
Alternative Author(s)
Jai Hong Lee
Advisor(s)
Jong-Kyu Lee
Issue Date
2010-08
Publisher
한양대학교
Degree
Doctor
Abstract
In this study, the classification of additional spillway was carried out according to topographical layout of existing spillway and additional spillway. Also, in order to analyze flow characteristics of additional spillway, the hydraulic model experiments and numerical simulations were carried out. It was performed to draw stage-discharge curve, to estimate discharge reduction factors of additional spillway and to confirm discharge reduction effects of additional spillway by using physical and numerical modeling. According to the type of additional spillway, close type and separate type additional spillway were used to hydraulic experiments and numerical simulations respectively for stage-discharge, discharge reduction effectiveness of additional spillway. The results of analysis of existing and additional spillway show good agreements among empirical calculation, hydraulic experiment, and numerical simulation. Also, when both existing spillway and additional spillway are operated at the same time, total flow rate through the two spillways reduced about 4.9% ~ 6.9% in case of close type additional spillway and about 1.5% ~ 3.0% in case of separate type additional spillway according to water depth. Additionally, the higher water surface level, the smaller the rate of outflow reduction. Consequently, the rate of flow over the two spillways has a tendency to decrease under such conditions of simultaneous gates opening due to interference each other. The next implementation of this study is to estimate discharge reduction factors of additional spillway. In this study, discharge reduction factors with the layout of the two spillways were estimated by the single regression analysis and the multiple regression analysis. Specifically, in order to confirm the effectiveness of reduction of discharge overflow existing spillway and additional spillway, 2 factors were selected, the one is the distance () between existing spillway and additional spillway and the other is the angle () between weir axis of existing spillway and weir axis of additional spillway. As a result, the results of multiple regression show good agreements between calculated and measured data by coefficient of determination 89.5% and 91.6% deviation respectively with level of significance 95%. For the purpose of verification of this study, results of comparing value of survey and estimating overflow rate were applied to study dam spillway with various design conditions. The hydraulic model experiment and numerical simulation were performed considering discharge reduction factors by multiple regression analysis. The results were identified as having very small errors. Hence, forecast of overflow rate for additional spillway was applicable to practical affairs. In order to confirm the reduction effectiveness of additional spillway, the discharge reduction factors of this study was applied to 2 existing dams. In case of close type additional spillway dam, the reservoir water level rose to 42 cm higher than those without application of reduction factor of discharge coefficient. This result means that it is necessary to enlarge net width of spillway for the safety of dam and spillway, in other words, the gates with 36 cm larger width on the weir crest is needed for optimal spillway design. Also, in case of separate type additional spillway dam, the reservoir water level rose to 12 cm higher than those without application of discharge reduction factor. This result means that it is necessary to enlarge net width of spillway for the safety of dam and spillway, in other words, the gates with 18 cm larger width on the weir crest is needed for optimal spillway design.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/141291http://hanyang.dcollection.net/common/orgView/200000414762
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > CIVIL AND ENVIRONMENTAL ENGINEERING(건설환경공학과) > Theses (Ph.D.)
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