• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.6
• /
• pp.21-31
• /
• 2018

The result of examination of diagnostic method, which is composed of a combination of a thermal camera and a drone that visually shows the temperature of the object by detecting the infrared rays, for detecting the leakage of earth dam was driven in this research. The drone infrared thermography method was suggested to precise safety diagnosis through direct comparing the two method results of electrical resistivity survey and thermal image survey. The important advantage of the thermal leakage detection method was the simplicity of the application, the quickness of the results, and the effectiveness of the work in combination with the existing diagnosis method.

• Korean Journal of Agricultural Science
• /
• v.50 no.3
• /
• pp.331-347
• /
• 2023

The downstream submergence damages caused during the flood season in 2020, around the Yongdam-dam and five other sites, were analyzed using related dam management data. Hourly- and daily-data were collected from public national websites and to conduct various analyses, such as autocorrelation, partial-correlation, stationary test, trend test, Granger causality, Rescaled analysis, and principal statistical analysis, to find the cause of the catastrophic damages in 2020. The damage surrounding the Yongdam-dam in 2020 was confirmed to be caused by mis-management of the flood season water level. A similar pattern was found downstream of the Namgang- and Hapcheon-dams, however the damage caused via discharges from these dams in same year is uncertain. Conversely, a different pattern from that of the Yongdam-dam was seen in the areas downstream of Sumjingang- and Daecheongdams, in which the management of the flood season water level appeared appropriate and hence, the damages is assumed to have occurred via the increase in the absolute discharge amount from the dams and flood control capacity leakage of the downstream river. Because of the non-stationarity of the management data, we adapted the wavelet transform analysis to observe the behaviors of the dam management data in detail. Based on the results, an increasing trend in the discharge amount was observed from the dams after the year 2000, which may serve as a warning about similar trends in the future. Therefore, additional and continuous research on downstream safety against dam discharges is necessary.

• Geotechnical Engineering
• /
• v.12 no.6
• /
• pp.65-78
• /
• 1996

The Chungpyung Dam is a 16 yearn old rock-fill dam for a Pumped storage hydro-Power plant, located in the middle of the Korean Peninsula. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus inducing a structural impact on the behavior of dam body, it draws attention of many engineering concerns. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, but in this study the seepage analysis was numerically performed by 2-D FEM thansient analysis. As a boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily change. As a res41t, the various seepage phenomena such as hydraulic gradient, seepage vector, and pore water pressure distribution were quantified at the corresponding time of interest as the water level rises and recedes. The seepage flux was also estimated and compared with the measured data which were both acceptable considering design criteria. The result proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

• Computers and Concrete
• /
• v.33 no.5
• /
• pp.481-496
• /
• 2024

Internal erosion around pipes can lead to the failure of earth dams through various mechanisms. This study investigates the displacement patterns in earth dam models under three different failure modes due to internal erosion, using digital image correlation (DIC) methods. Three failure modes—erosion along a pipe (FM1), pipe leakage leading to soil erosion (FM2), and erosion in a pipe due to defects (FM3)—are analyzed using two- and three-dimensional image- processing techniques. The internal displacement of the cross-sectional area and the surface displacement of the downstream slope in the dam models are monitored using an image acquisition system. Physical model tests reveal that FM1 exhibits significant displacement on the upper surface of the downstream slope, FM2 shows focused displacement around the pipe defect, and FM3 demonstrates increased displacement on the upstream slope. The variations in internal and surface displacements with time depend on the segmented area and failure mode. Analyzing the relationships between internal and surface displacements using Pearson correlation coefficients reveals various displacement patterns for the segmented areas and failure modes. Therefore, the image-based characterization methods presented in this study may be useful for analyzing the displacement distribution and behavior of earth dams around pipes, and further, for understanding and predicting their failure mechanisms.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.61 no.1
• /
• pp.131-144
• /
• 2019

The purpose of study was to determine the hygrophyte index of each plant(HIP) considering the moisture environment condition (MEC) of the native plants on the downstream slope of the fill dam and evaluate its applicability which to develop a method to search for leaks and saturated zones of the fill dam for status evaluation of precision safety diagnosis. The HIP was weighted average and consisted of 19 ranks. The weighted average was calculated according to the following three procedures: First, the linear assumption was made according to the actual habitat environmental conditions, the second one was weighted to 10% of the optimal habitat condition, and finally the average value of the distribution range values. The Hygrophyte index of vegetation at each plot (HIV) was obtained from the Sinheung reservoir (Yesan-gun, Chungcheongnam-do) using the results of vegetation survey of the Sinheung reservoir with precision safety diagnosis and suggested the use of the hygrophyte index of the cultivated vegetation. The average HIP range of plant species that emerged in 50 survey sites on the downstream slope of the Sinheung reservoir is 2.99 to 3.56. The coefficient of variation showed a large difference depending on the appearance of the leakage indicator plant(LIP) species. The range of HIV is 2.80 to 4.26, the mean value is 3.37, standard deviation is 0.37 and the coefficient of variation is 9.7%. As a result, the value of the coefficient of variation showed a large difference depending on the appearance of the plant species.

• 한국지구물리탐사학회:학술대회논문집
• /
• 1999.08a
• /
• pp.240-257
• /
• 1999

More than 16 percent of the total 18,032 reservoirs over the country were reported to have leakage problems and need to be improved. Recently, a great deal of progress was made in geophysical survey techniques, particularly in electrical resistivity, and the techniques are used for variety of Purposes in groundwater and dam management due to its economical advantages. This document describes the re-evaluation of existing resistivity data including newly surveyed data, mapping of modeled value in 2-D analysis to locate seepage pathways, This contains also discussion results of more than eighteen years of professional experiences in the field of dam efficiency improvement. In comparison of surface resistivity data with several soil analysis data in laboratory, it is evident that the surface resistivity value shows a qualitative proportionality with the sand contents of the filling materials in earth dam. The result from the study also indicates that the SP method in subsurface investigation is effective to detect seepage in earth filled dam as well as piping through rock/earthfill dike.

• Journal of the Korean Geosynthetics Society
• /
• v.8 no.2
• /
• pp.31-39
• /
• 2009

The purpose of present study performed 27 CFRD cases analyses to predict and effectively use post-construction crest settlement, face slab deformation, and leakage as indexes for the maintenance and management of concrete faced rockfill dams(CFRD). The results showed that the range of post-construction crest settlement suggested by Sherard and Cooke (1987), and Clements (1984) had a good agreement in the case analyses using rockfills with very high intact strength, but it had a trend which underestimated crest settlement in the cases using rockfills with medium to high intact strength. The leakage case analyses showed that leakage is mainly caused by face slab deformation due to the water load, the maximum leakage in general was observed during the first reservoir filling, and leakage was rapidly increasing when the dam height exceeds 125m.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2005.05a
• /
• pp.15-20
• /
• 2005

Defects of dam body which can be induced in seepage or leakage procedure can directly affect dam safety. Therefore, a proper inspection method should be carried out in the first place to find out their positions and sizes, After that, some reinforcement works such as grouting and the corresponding assessment could be taken in a proper way. The dam(center core type earth dam) issued in this study has been in need for intensive diagnosis and reinforcement work, because a lot of slumps similar to cracks, seepage and some boggy area have been observed on the downstream slope. High resolution seismic reflection method was performed on the crest profile twice before and after grouting work(Aug. 2001 and Nov. 2004) aimed at the dam inspection and the assessment of grouting efficiency as well. To enhance the data resolution, P-beam energy radiation technique which can reduce the surface waves and hence to reinforce the reflection events was used. Strong reflection events were recognized in the stack section before grouting work, It seems that the events would be caused by e.g. horizontal cracks with a considerable aperture, Meanwhile such strong reflection events were not observed in the section after grouting. That is, the grouting work was dear able to reinforce the defects of dam body. Hence, the section showed an well arranged picture of dam inner structure. In this sense, seismic reflection method will be a desirable technique for dam inspection and for monitoring dam inner structure as well.

• Journal of the Korean Geophysical Society
• /
• v.8 no.1
• /
• pp.1-6
• /
• 2005

Defects of dam body which can be induced in seepage or leakage procedure can directly affect dam safety. Therefore, a proper inspection method should be carried out in the first place to find out their positions and sizes. After that, some reinforcement works such as grouting and the corresponding assessment could be taken in a proper way. The dam(center core type earth dam) issued in this study has been in need for intensive diagnosis and reinforcement work, because a lot of slumps similar to cracks, seepage and some boggy area have been observed on the downstream slope. High resolution seismic reflection method was performed on the crest profile twice before and after grouting work(Aug. 2001 and Nov. 2004) aimed at the dam inspection and the assessment of grouting efficiency as well. To enhance the data resolution, P-beam energy radiation technique which can reduce the surface waves and hence to reinforce the reflection events was used. Strong reflection events were recognized in the stack section before grouting work, It seems that the events would be caused by e.g. horizontal cracks with a considerable aperture. Meanwhile such strong reflection events were not observed in the section after grouting. That is, the grouting work was dear able to reinforce the defects of dam body. Hence, the section showed an well arranged picture of dam inner structure. In this sense, seismic reflection method will be a desirable technique for dam inspection and for monitoring dam inner structure as well.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.449-456
• /
• 2000

Remediation grouting has been widely used for the rehabilitation of various civil works like hydraulic and traffic structures. Recently there were some cases of remediation grouting for repairing old dams in korea. So this study will describe the case of remediation grouting of the concrete dam base located east-northern part of Seoul. We use Lugeon Test and Borehole Image Processing System(BIPS) for estimating the effectiveness of remediation grouting of this project. As the results of this study, we could find the lots of joints between the old concrete body and the weathered rock base. So the about 30% quantity of total cement grouts was injected at the boundary surface between concrete and rock base. And Lugeon Test and BIPS could be compared relatively because BIPS results could be presented quantitatively as well as qualitative analysis. Finally, we could find microfine cement was very effectively injected to the fine fissured concrete body compared with ordinary portland cement, but there was little injectability differences beteween microfine cement and ordinary portland cement at the large cracks or cavities were developed rock base.