• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.337-345
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• 1998

DAMBRK-U model is developed for the evaluation of overtopping risk of dam and levee and for the estimation of uncertainty in floodwave simulation. The original algorithm is revised and expanded to include Monte-Carlo analysis to estimate them. The model is tested by applying to hypothetical channels of widening, uniform and narrowing geometry. Larger variation in discharge and water depth are expected at narrower sections of a river. It is calibrated by applying to the Hantan River, where severe damages from Yunchun dam-break and levee overtopping occurred on July, 1996. Overtopping risk of dam is calculated for various discharge conditions for Yunchun-dam, and that of levee is also calculated by comparing levee height with flood level at Hantan recreation area. Simulation results show that the overflow depth of flood level is 1,266~0.782 m and the overflow risk turns out to be 100%.

• Computers and Concrete
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• v.29 no.4
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• pp.209-217
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• 2022

In order to analyze the static and dynamic structural characteristics of the Obermeyer gate under overflow conditions, the force characteristics and vibration characteristics of the shield plate structure are studied based on the fluid-solid coupling theory. In this paper, the effects of the flow rate, airbag pressure and overflow water level on the structural performance of shield plate of air shield dam are explored through the method of controlling variables. The results show that the maximum equivalent stress and total deformation of the shield plate decrease first and then increase with the flow velocity. In addition, they are positively correlated with the airbag pressure. What's more, we find that the maximum equivalent stress of the shield plate decreases first and then increases with the overflow water level, and the total deformation of the shield plate decreases with the overflow water level. What's more importantly, the natural frequency of the shield structure of the Obermeyer gate is concentrated at 50 Hz and 100 Hz, so there is still the possibility of resonance. Once the resonance occurs, the free edge of the shield vibrates back and forth. This work may provide a theoretical reference for the safe and stable operation of the shield of the Obermeyer gate.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.3
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• pp.9-18
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• 2007

The small and medium sized dams have the fill dam type of a lot of occasions, which are often weak in cases of major floods. For this reason, although a countermeasure is in great need, due to the importance of the facilities and financial situations, no direct safety measures have been taken. In this study, in order to minimize construction expenditure for practical safety measures in cases of major floods, the overflow section of spillway has been analyzed focusing on how the overflow capacity will increase in the case of partially rebuilding a part of the overflow section of spillway favorable for hydraulic conditions. The labyrinth weir and movable weir was chosen for reconstruction models of the overflow section. Moreover, for analyzing the after-effects of the reconstruction, a small scale dam was temporarily chosen for various experiments such as the hydraulic model testing and the three dimension numerical evaluation through the use of Flow-3D.

• Computational Structural Engineering
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• v.9 no.4
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• pp.189-198
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• 1996

The fracture behaviour of concrete gravity dam mainly due to uplift pressure acting at the crack face was studied. Triangular type and parabolic type distribution of the uplift pressure including uniform type were first considered in case of calculating stress intensity factor(SIF) by the surface integral method. Second, the directions of crack propagation according to the uplift pressure distribution were pursued by FRANC(FRacture ANalysis Code). Third, critical crack lengths according to the uplift pressure distribution under the overflow depth were calculated. The SIF values obtained from the surface integral method were compared with those by FRANC and relatively good agrements could be obtained between both of them. And it could be seen that the direction of crack propagation in case of triangular pressure distribution was a little benter to the dam base than the one by the uniform type. Maximum critical crack lengths under the overflow depth were obtained at about 2/5-1/2 of the dam height.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.328-334
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• 2003

Evaluating stability of dam foundations is one of the prime areas of any rock engineering investigations. Despite best engineering efforts in the design and construction of dam foundations, the foundation regime of a constructed dam suffers deterioration due to continuous erosion from backwater current of dam discharge and dynamic effects of loading and unloading process. Even during construction, development of frequent cracks due to sudden thermal cooling of concrete blocks is not uncommon. This paper presents two case studies from India and Bhutan. In the first case, the back current of water discharge from the Srisailam dam in India had continuously eroded the apron and has eaten into the dam foundation. In the second case with dam construction at Tala Hydroelectric Project in Bhutan, sudden overflow of river during the construction stage of dam had led to development of three major cracks across the dam blocks. This was ascribed to adiabatic cooling effect of concrete blocks overlain by chilled water flow. Non-destructive evaluation of rock mass condition in the defect regime by the borehole GPR survey helped in arriving at the crux so as to formulate appropriate restoration plan.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.371-381
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• 2018

Domestic agricultural reservoir dam facilities are difficult to manage water resources because of the in summer rainfall increase due to aging and climate change, it is expected that the dam risk will be large due to the overflow. In this study, author selected study basin in order to evaluate hydrological safety of agricultural reservoir dam facilities. And calculated the probable rainfall, Present PMP, Future PMP considering climate change. Also, author carried quantitative analysis out for increasing rainfall due to climate change, analyze freeboard assessment of agricultural reservoir by calculate flood discharge, reservoir flood routing according to rainfall scenarios. As a result of evaluate hydrological safety of agricultural reservoir dam facilities using Future PMP considering climate change, Gosam, Kumkwang, Miho, Cheongcheon reservoir had the Highest Water Level over the design flood level, it is analyzed that it would be vulnerable to overflow risk.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.181-191
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• 2019

Most of the reservoirs in South Korea are fill dam, and overflow and piping phenomena have been detected as the main causes of failure of fill dam. In this study, an operating ◯◯ reservoir located in Gongju-si is modeled in centrifuge model test to study the behavior of reservoir during water level rise and overflow conditions. In order to simulate seepage and overflow in the real reservoir, the model was constructed in 1/50 scale, and deteriorated and reinforced conduits were installed. After modeling the reinforced and deteriorated conditions of the conduits, LVDTs, pore pressure gauges were installed and centrifuge model tests were carried out with water level rise and overflow conditions in order to analyze the reservoir behavior according to the reinforcement methods. The results of centrifuge model test in water level rise condition show that deteriorated conduit has adverse effects in the stability of the reservoir body, and the conduit which is reinforced by the inverse lining method has enhanced stability of the reservoir body. Moreover, installation of water spillway is seen to prevent the scour and erosion of the reservoir body. The study provides a basic data required for the reinforcement of conduit and water spillway in the reservoir.

• Journal of Ocean Engineering and Technology
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• v.21 no.1 s.74
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• pp.25-30
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• 2007

Most of dams and reservoirs were made from natural materials, such as soil, sand and gravel. This type of hydraulic structure has the danger of collapse by overflow during a flood. Freeboard is the vertical distance between the crest of the dam and the full supply level in the reservoir. It must be sufficient to prevent overtopping from over flow. Thus, freeboard determination involves engineering judgment, statistical analysis, and consideration of the damage that would result from the overtopping of a hydraulic structure. This study attempts to calculate the wave height in dam, which is needed for the determination of the freeboard of the dam. Chung-ju dam is selected as the study area. Using the empirical formulas, the wave heights in dam were calculated, and the results were compared with those by the SWAN model, which is a typical wave model. The difference between the calculated results from the empirical formulas and those by the SWAN model is considerably large. This is because empirical equations consider only fetch or fetch and wind velocity, while the SWAN model considers depth and topography data as well.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.743-746
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• 2008

Recently, due to the effect of global warming and extreme rainfall, the magnitude of flood disaster and the frequency of flood is rapidly increasing. In order to mitigate the damage of human and property from this kind of meteorological phenomenon and manage water resources scientifically, effective operation of dam and reservoir is very important. In case of Andong dam which was not performed a flood control function needs to develop new types of dam safety management measure because of recent extraordinary flood by typhoons. In case of Andong dam and Imha dam, I am using HEC-5 model in order to apply reservoir simulation. In this case, complex conditions among 100-year floods , 200-year floods and PMF was used. Also, I modified the maximum outflow 3,800m3/s into 3,490m3/s and applied this modified discharge in order to secure freeboard in the downstream. In an analysis that I applied modified outflow by 100-year floods and 200-year floods to, the result showed that river didn't overflow in Andong area but some other places have relatively low freeboard. In the cases that I modified maximum outflow, results showed that freeboard of levee is larger than existed simulation. In the simulation that I applied 200-year floods and PMF to and under a condition connected with PMF, results showed overflowing the levees. Because of the difference between the frequency of dam outflow and the design flood in river, it is required to improve the existed flood plan in the downstream of Andong dam. As a result of this study, the optimal operation of reservoir systems can be proposed to mitigate the flood damage in the downstream of Andong dam and also can be used to establish the flood plans.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.299-302
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• 2003

This study aims to apply and compare flood routing methods for irrigation reservoirs. In this research, three methods, which are the storage indication method(SIM), the mass curve method(MCM), the frog method(FM) were adopted and applied to two storm events of July $9{\sim}10\;and\;22{\sim}23$ of Donghwa-dam and its watershed located on Jangsoo-gun, Chunnam province. As the application results MCM showed the highest value at peak overflow and goodness-of-fit to the observed value, although the others also had similar value with the observed one. In analyzing lag time of peak between inflow and overflow MCM and SIM showed 7 hours, while FM showed 6 hours for the first storm event, and all three methods showed 3 hours for the second event.