• Journal of the Korean Geotechnical Society
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• v.23 no.1
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• pp.39-49
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• 2007

In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest settlement of CFRD (Concrete-Faced Rockfill Dam) subjected to earthquake loading was carried out. The purpose of this study is to indicate the most important input parameter from the results of sensitivity analysis, to show the quantitative variation of settlement at the crest of CFR type dam during earthquake with this input parameter, and to recommend the approximate estimation method of the settlement on the crest of CFRD subjected to earthquake loading. The statistic characteristics of rockfill parameters which were obtained from large triaxial tests were evaluated. The total 108 dynamic numerical analyses (2 input earthquake, 2 magnitudes for each earthquake, 27 rockfill material property combinations) on CFRD were conducted. The global sensitivity analysis was carried out using the results of numerical analysis. From the sensitivity analysis, It was found that the crest settlement of the CFRD subjected to earthquake was absolutely affected by the shear modulus of rockfill material irrespective of the input earthquakes and the magnitude of input acceleration. On the contrary, it was found that the effect of cohesion and friction angle of rockfill was negligible. From the results of sensitivity analysis and numerical analysis, the approximate estimation method of the settlement on the crest of CFRD subjected to earthquake loading was recommended on condition that the rockfill shear modulus and simple dam information was known.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.103-116
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• 2018

The purposes of this research are as follows: First, to reconstruct the optimal locational environment of the Bronze Age settlement in Cheonan Baekseok-dong (hereinafter referred to as the study settlement). Second, to identify the priority ranking of the topographical factors that influenced the Bronze Age people when selecting their the settlement location. For these reasons, the topographical factors of the 200 Bronze Age dwellings (hereinafter referred to as dwellings) confirmed in the survey area were analyzed through the ridge's environmental perspective. The results are asfollows: First, the optimal ridge environment of the Bronze Age settlement is largely a sub-ridge in N-S direction (for example, NNW-SSE, N-S, NNESSW), especially at the top (Crest slope, Crest flat) of the south-facing aspect of the ridge. Second, when the Bronze Age dwellers selected a residential location, they carefully considered topographical factors in the following order: (1) the slope direction of the ridge surface, (2) the micro-landform of the ridge, (3) the ridge scale, (4) the ridge direction, and (5) the surface relief. The results of this study could be used as basic data in related fields such as archaeology, quaternary research, and traditional architecture and so on.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.351-357
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• 2006

In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) subjected to earthquake loading was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam during earthquake loading with this input parameter. From the sensitivity analysis, it was found that the crest displacement of CFR type dam subjected to dynamic loading was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the extent of effect of shear modulus on the displacement at the crest of CFRD due to dynamic loading decreased as maximum amplitude of input acceleration increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.5
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• pp.509-520
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• 2020

Currently, the criteria for input motions used in dam seismic design are clearly presented in general provisions of seismic design (KDS 17 10 00), and seismic ground motion records should be matched to the standard design response spectrum. However, the effect on the results is not assessed according to the selection of the seismic ground motion records, making it difficult to select seismic input motions. Therefore, in this study, the change in the amount of crest settlement of an embankment dam was assessed through numerical analysis after matching the seismic ground motion records of domestic and overseas earthquakes in accordance with the standard design response spectrum provided in the seismic design code (KDS 17 10 00). The results showed that the behavior of the upper part of the embankment, such as maximum acceleration at the crest and amplification through the dam, rather than the effect of free-field acceleration, had a greater effect on the amount of crest settlement. Moreover, it was confirmed that even an input seismic motion matched to the standard design response spectrum can make a difference in settlement depending on the characteristics of amplification through a dam body.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.315-328
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• 2019

This paper presents an investigation on bearing capacity, load-settlement behavior and safety factor of rock-soil slopes reinforced using geogrid-box method (GBM). To this end, small-scale laboratory studies were carried out to study the load-settlement response of a circular footing resting on unreinforced and reinforced rock-soil slopes. Several parameters including unit weight of rock-soil materials (loose- and dense-packing modes), slope height, location of footing relative to the slope crest, and geogrid tensile strength were studied. A series of finite element analysis were conducted using ABAQUS software to predict the bearing capacity behavior of slopes. Limit equilibrium and finite element analysis were also performed using commercially available software SLIDE and ABAQUS, respectively to calculate the safety factor. It was found that stabilization of rock-soil slopes using GBM significantly improves the bearing capacity and settlement behavior of slopes. It was established that, the displacement contours in the dense-packing mode distribute in a broader and deeper area as compared with the loose-packing mode, which results in higher ultimate bearing load. Moreover, it was found that in the loose-packing mode an increase in the vertical pressure load is accompanied with an increase in the soil settlement, while in the dense-packing mode the load-settlement curves show a pronounced peak. Comparison of bearing capacity ratios for the dense- and loose-packing modes demonstrated that the maximum benefit of GBM is achieved for rock-soil slopes in loose-packing mode. It was also found that by increasing the slope height, both the initial stiffness and the bearing load decreases. The results indicated a significant increase in the ultimate bearing load as the distance of the footing to the slope crest increases. For all the cases, a good agreement between the laboratory and numerical results was observed.

• Journal of The Geomorphological Association of Korea
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• v.27 no.4
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• pp.89-112
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• 2020

The purpose of this study is as follows: First, we restore the optimal topographical environment of the Bronze Age settlements in the Yongdu Stream and its surrounding area in Asan City. Second, we reveal the relative importance of the topographical factors that the Bronze Age people considered when selecting their dwelling locations. We compared and analyzed topographical factors (ridge scale, ridge direction, slope direction of the ridge, micro-landform of the ridge, position of the ridge) from the ridge's environmental perspective of 123 Bronze Age dwellings (hereinafter referred to as dwellings) found in the survey area for that purpose. The results are as follows: First, from a macro perspective, the optimal topographical environment for the location of the Bronze Age settlement is the second ridge that have the E-W direction. And from a micro perspective, it is the southeast direction slope of the Crest slope at the summit. Second, it appears that the Bronze Age people have taken important consideration in determining the location of their dwelling in the following order: ① position (eg. summit), ② micro-landform (eg. Crest slope, Upper slope), ③ slope direction (eg. southward, South, Southeast), ④ scale (eg. sub-ridge, secondary, tertiary), ⑤ direction (eg. E-W, NNE-SSE).

• Journal of the Korean GEO-environmental Society
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• v.14 no.11
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• pp.33-46
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• 2013

Recently, the projects which are to increase the capacity of the flood control are being actively performed because of the abnormal climate changes throughout the country. In this study, the regression analysis was performed using both Kelvin model and the real settlement measured at the crest of the existing concrete face rockfill dam(CFRD) to estimate the long-term deformation behavior characteristics such as creep which occurs without additional load. In addition, the effects on changes in physical properties (E, G, K) of the dam construction materials by deformation characteristics of the dam were evaluated, and the reasonable stability analysis method of the dam was proposed to obtain the long-term stability considering the changes in physical properties induced by the long-term deformation behavior in case of heightening the existing dams.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.63-73
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• 2014

In this study, the large scale test was performed to investigate the behavior of failure on the embankment and spillway transitional zone by overtopping. The pore water pressure, earth pressure, settlement and failure behaviors according to several reinforcing method were compared and analyzed. The pore water pressure showed a small change in the spillway transition zone and core, indicating that the riprap and geotextile efficiently reinforced the embankment, but non-reinforcement showed a largely change in pore water pressure. The earth pressure by riprap and geotextile at upstream slope and bottom core increased rapidly with the infiltration of the pore water by overtopping. And the earth pressure at crest showed a smally change due to effect of the inclined core. A settlement by riprap showed a small change and the geotextile decreased a rapidly due to failure of crest. The width of failure by riprap at intermediate stage (50 min) showed a largely due to sliding of crest. But, the width and depth of the seepage erosion after the intermediate overtopping period (100 min) were very small due to the effect of riprap than geotextile and non-reinforcement which delayed failure. It has the effect that protect reservoir embankment from erosion in the central part. The pore water pressure at the spillway transition zone due to overtopping increased a rapidly in the case of non-reinforcement, but the reinforced methods by geotextile and riprap showed a smally change. Therefore, the reinforced method by riprap and geotextile was a very effective method to protect permanently and the emergency an embankment due to overtopping, respectively.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.282-291
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• 1985

In order to investigate the settlement characteristics of fill dam with decomposed granite is used as a embankment material instead of conventional clay collected behavoir of Andong dam and analyzed. Andong dam is the use of decomposed granite in the embankment material, and various type of gauges were installed in dam to measure a pore pressure, interval vertical settlement, dam crest settlement, relative settlement, surface settlement and internal horizontal movement. The results were summerized as follows; 1. With the increase of embankment loading, the settlement of core zone during construction increased with linear and under the effective stress $7kg/cm^2$ vertical settlement ratio ranged between 0.1 and 0.8% approximately and showed smaller value than that of fill dam with clay were used as a embankment material. 2. Though embankment loading was increased with about over central part of embankment height, the settlement of core zone in the lower part of the embankment was influenced slightly. 3. Pore pressure responsed sensitively with the increase of coefficient of permeability in core zone and settlement increased with pore pressure were dispersed. 4. During construction relative settlement in the lower part of the embankment has the largest influence on magnitude of the relative density and after construction settlement showed larger value in the core zone which has the largest compression height. 5. Settlement distribution of dam crest showed larger value in the central part, maximum section of dam, but smaller value in near the abutment.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1155-1166
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• 2021

In this study, statistical analysis was performed to suggest the optimal analysis techniques for the main measuring instruments of the fill dam, such as seepage, crest settlement, and porewater pressure gauge. In addition, correlation analysis with water level and rainfall data was performed. Based on the results of descriptive statistical analysis for each instrument, porewater pressure gauges could be classified into 3 groups or 2 groups through principal component analysis, In the case of the group having a high correlation with the water level instrument, the correlation between the gauges was also large. In the case of seepage instrument, the distribution showed an extremely asymmetric distribution, so for quantitative analysis, the average seepage during non-precipitation and precipitation could be estimated through decision tree analysis. In the case of the crest settlement instrument, the correlation analysis showed that the correlation between the gauges was large, but the relationship with the water level instrument did not show a significant linear relationship, so EMD analysis was performed to analyze it in more detail. It is judged that principal component analysis, decision tree analysis, and data filtering method can be applied to analyze the behavior of pore water pressure meters, seepage, and crest settlement instrument as major measurement items of fill dam.