• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.83-83
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• 2023

댐의 침투수량은 준공이후 댐 안전성 확보를 나타내는 지표 중의 하나이며, 유지관리를 위해 침투수량 측정을 실시하여 관리를 하고 있다. 댐 타입별로 침투수량에 대한 허용치와 관리기준치는 다르지만, 기본적으로 댐에서 발생되는 침투수량은 측정범위를 넘지 않도록 관리를 하고 있다. 댐의 침투수량 측정은 댐 하류에 누수집수벽을 설치하고 댐에서 발생되는 침투수량을 집수한 후 삼각위어를 통하여 침투수량을 측정하고 있다. 이러한 침투수량 측정은 대부분의 댐에서 실시간으로 자동측정하고 있지만, 경우에 따라 미계측 구간이 발생되어 댐 유지관리 측면에서 미계측에 대한 원인분석이 필요한 실정이다. 일반적으로 침투수량의 미계측 원인은 계측기기, 삼각위어, 누수집수벽, 기초지반 등 다양한 원인이 있지만 명확한 원인을 찾기는 어려움이 많다. 특히, 댐 침투수량의 경우 지하수위, 댐 표면 우수, 침투수가 같이 측정되기 때문에 원인분석을 위해서는 다양한 검토가 필요하다. 본 연구의 표면차수벽형석괴댐은 누수집수벽을 통하여 침투수량을 측정하고 있으나, 일부 구간 미계측 부분이 발생하여 기초지반, 댐체 하류사면, 여수로와 댐체 접합부를 통한 누수를 원인으로 추정하였다. 이를 조사하기 위하여 전기비저항 탐사, 시추조사, 수압시험, 지하수위 측정 결과를 이용하여 누수발생 추정위치를 찾고, 침투수량이 미계측되는 원인을 분석하고자 하였다. 전기비저항 탐사는 여수로 접합부, 누수집수벽 상·하류 구간을 선정하여 측정한 결과 상·하류 저비저항대가 존재하는 구간을 추정할 수 있었다. 수압시험 결과 기초암반은 2.3 ~ 21.3 Lu(3.65×10^-5 ~ 3.65×10^-4 cm/sec)의 범위로 누수 가능성이 있는 높은 투수성을 갖는 부분을 확인할 수 있었다. 전기비저항 탐사, 수압시험, 지하수위 측정을 통해 누수집수벽 기초지반 누수발생 원인분석 결과 누수집수벽 기초암반을 통한 누수로 누수집수벽에 댐체를 통한 침투수량이 저류되지 못하는 현상이 발생하기 때문인 것으로 판단되었다. 침투수량계의 정상화를 위해서는 조사를 통해 확인된 누수집수벽 기초암반 누수구간의 그라우팅 보수보강이 필요함을 확인하였다.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.5-13
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• 2013

The water leakage of reservoir embankment usually occurs around channelling pipes, which gives little influence on the embankment in a normal state. However, the embankment can be destroyed when the water level of reservoir increases with heavy rain and the rainy season in summer. Investigating the water vein and its path is therefore very important from the viewpoint of disaster prevention and embankment maintenance. The water leakage in dams and levees where the channelling pipes are working as weak zone was analyzed by using both numerical simulation and experimental method in this study. To detect the water leakage, an electrical resistivity survey was used and investigated for its' usability. The numerical results show the size and location of weak zone increases the importance of selection of electrode spacing. The leakage experiments of model embankment present the best result is obtained under the conditions of electrode spacing of 0.3m and dipole-dipole array. By studying the water leakage in dams and levees, the electrical resistivity survey is observed it is a very useful method to predict the leakage.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.13-23
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• 2006

The sinkhole and leakage in dam core were detected at one of earth fill dams in Korea. The damage areas in the core of the dam were repaired by compaction grouting method. This study is to evaluate compaction grouting activity by in-situ and laboratory experiments before, during and after the remedial work. The intensive site investigation and geophysical survey were conducted during and after the compaction grouting work. The compaction grouting work was carried out for the damaged dam core between June 16 and August 24, 2000. The leakage reduction generally occurred in the core of the dam after the remedial work. The use of compaction grouting was considered the proper countermeasures for repairing the damaged dam. It shows that the loose or voided zones have been properly filled and the leakage has been reduced by about 96% of that before the treatment of the remedial work performed at dam core by compaction grouting.

• Journal of the Korean Geophysical Society
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• v.6 no.3
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• pp.189-207
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• 2003

The purpose of this paper is to analyze the behavior and to study the safety evaluation of the Unmun Dam located in Cheongdo-Gun of GyeongBuk Province, Korea. For this purpose, soil analyses including boring data, geophysical surveys and monitoring the buried geotechnical gauges, such as pore-pressure gauge, earth-pressure gauge, displacement gauge, multi-layer settlement gauge, leakage flow-meter, were conducted. In addition to these data, numerical analyses of behavior of dam were performed to predict and to compare the data which were obtained from the above methods. Since many defects, such as gravel and weathered rock blocks in the dam core, and lots of amounts of leakage, by boring analyses were found, reinforcement by compaction grouting system (CGS) has been conducted in some range of dam. Some geotechnical gauge data were also used to confirm the effects of reinforcement. Analyses of monitoring the data of geotechnical gauges buried in the dam, such as pore-pressure gauge, earth-pressure gauge, displacement gauge, multi-layer settlement gauge, and leakage flow-meter shows the load transfer of dam and the possibility of hydraulic fracturing. As a conclusion, some problems in the dam found. Especially, the dam near spillway shows the high possibility of leakage. It should be pointed out that only the left side of he dam has not a leakage problem. As a whole, the dam has problems of weakness, because of unsatisfactory construction. It is strongly recommended that highly intensive monitoring is required.

• Water for future
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• v.54 no.4
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• pp.80-86
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• 2021

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1221-1234
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• 2013

The purpose of this study is to suggest the methodology for the computation of uplift pressure and discharge of the seepage flow under gravity dam. A 3-dimensional FDM model is developed for this purpose and this model can simulate the saturated Darcian flow in heterogeneous media. For the verification of the numeric model, test simulation has been executed and the mass balance has been checked. The error does not exceed 3%. Using the developed model, The uplift pressure and seepage flow discharge under gravity dam has been calculated. The uplift pressure shows the similar pattern, comparing with the result of flow-net method. As the length of grout curtain increases, the uplift pressure decreases linearly, but the seepage flow discharge shows the non-linear decreasing pattern. The coefficients of the formulas in the dam-design criteria have been analysed, and ${\alpha}=1/3$ corresponds to the value when the length of curtain grout is 70% of the aquifer height. The uplift pressure near the pressure relief drain has the big curvature vertically and horizontally. The developed model in this study can be used for the evaluation of the effects of seepage flow under gravity dam.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.563-572
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• 2010

Both multi-channel temperature monitoring and geophysical electric survey were performed together for an embankment to assess the leakage zone. Temperature variation according to space and time on the inner parts of engineering constructions (e.g.: dam and slope) can be basic information for diagnosing their safety problem. In general, as constructions become superannuated, structural deformation (e.g.: cracks and defects) could be generated by various factors. Seepage or leakage of water through the cracks or defects in old dams will directly cause temperature anomaly. This study shows that the position of seepage or leakage in dam body can be detected by multi-channel temperature monitoring using thermal line sensor. For that matter, diverse temperature monitoring experiments for a leakage physical model were performed in the laboratory. In field application of an old earth fill dam, temperature variations for water depth and for inner parts of boreholes located at downstream slope were measured. Temperature monitoring results for a long time at the bottom of downstream slope of the dam showed the possibility that temperature monitoring can provide the synthetic information about flowing path and quantity of seepage of leakage in dam body. Geophysical data by electrical method are also added to help interpret data.

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

• Geophysics and Geophysical Exploration
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• v.19 no.4
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• pp.200-211
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• 2016

To support cross potential array and direct potential array, the array for leakage detection of all kinds of water facilities is proposed and it is named as the D-Lux array. The D-Lux array data are arranged to a coloured matrix and it is called the D-Lux view. Low potential difference of anomalous zone shown in D-Lux view implies the indication of leakage zone. Furthermore, for an intuitive interpretation of D-Lux array, equipotential distribution map is made by using D-Lux and direct potential array data. Equipotential distribution map makes us possible to predict import point, export point and the path of water leakage that we could have not anticipated in D-Lux view and the graphs. The water tank experiment and numerical analysis were carried out as preparatory experiment and the field explorations were conducted at a concrete weir and a fill dam. As a result, effective and specific detection of leakage path was possible for the concrete weir and the fill dam.