• Journal of the Korean Geotechnical Society
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• 제22권4호
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• pp.73-83
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• 2006

Seepage analysis through unsaturated zone based on the theory of unsaturated flow is commonly performed to evaluate dam safety. However, the concepts of unsaturated soil behavior have not been transferred into the hands of practicing geotechnical engineers since the problems involving unsaturated soils often have the appearances of being extremely complex. There is variability and uncertainty associated with the unsaturated hydraulic properties that in turn will lead to variability in predicting unsaturated soil behavior such as seepage rate and the pore water pressure distribution. In this paper, measurements of the soil-water characteristic curve and saturated hydraulic conductivity for the core material of dam were conducted. Then, finite element stochastic analysis was used to capture the effect of unsaturated hydraulic properties on the seepage behavior of dam. It is observed that the amount of seepage increases, as the values of unsaturated soil parameters a and n increase. The values of m and p showed opposite trend.

• The Journal of Engineering Geology
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• 제17권1호
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• pp.41-47
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• 2007

Geotechnical Phenomena such as landslide, groundwater recharge and groundwater fluctuation due to rainfall can be explain to use a dielectric response and infiltration variation by the movement of a wetting front in the subsurface. The infiltration of a wetting front is infiltrating to the connected pores which are distributed in unsaturated soil. In this study we carried out to laboratory experiment of a vertical infiltration column test using ethanol mix-ing tracer which has same the specific gravity of water. All physical values are detected to use a variation of dielectric constant and calculated to use a dielectric mixing model and tracer test model. This dielectric method measured by each dielectric constant of geological soil porous materials should be of for the geotechnical information and useful a field monitoring technique for detecting the variations of the volumetric water content and the wetting front, which are insignificant the key parameter to understanding the landslide by rainfall.

• Journal of the Korean Society for Marine Environment & Energy
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• 제6권3호
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• pp.37-44
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• 2003

To know the penetration behavior of spilled oil into sandy beach sediment is very important, because the penetration depth of the stranded oil into the sediments is one of the most significant information to know effect of spilled oil on biological communities and to set up cleaning method. The purpose of this study is to clarify the effects of wave and/or tidal action on penetration of spilled oil into the sediments and to clarify main factor in oil penetration using sandy beach model. Specific conclusions derived from this study are as follows. Spilled fuel oil C penetrated into the sediments only by falling tidal fluctuation and not by wave action on sandy beach environment, and the first tide is most important for the penetration of stranded oil. Over 80% of bulk fraction in penetrated fuel oil C was concentrated to the top 2 cm sediment-layer. Moreover, the penetration of stranded oil into the sandy beach sediments was strongly correlated with the oil viscosity affected by temperature.

• Journal of the Korean Ceramic Society
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• 제37권9호
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• pp.909-914
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• 2000

반응금속 침투법으로 제조한 $Al_2$O$_3$/Al 복합체의 파괴특성과 손상 내구성을 침투방향성에 따라 관찰하였으며, 복합체는 $Al_2$O$_3$단일상보다 향상된 파괴인성과 Al 단일상보다 높은 경도값을 나타내었다. Vickers 압입법을 사용한 복합체의 손상형태에서는 침투방향에 따른 각각의 미세구조에 의해 상이한 특성을 나타내었으며, 헤르찌안 압입법을 사용한 복합체의 손상거동은 $Al_2$O$_3$과 Al의 중간거동을 나타내었다. 헤르찌안 압입 후 강도저하시험으로 복합체가 갖는 우수한 결함저항성을 관찰할 수 있었으며, 높은 헤르찌안 하중에서는 복합체의 강도저하 특성이 복합체의 미세구조에 의존함을 관찰할 수 있었다. 이와 함께 복합체에서의 반응금속 침투방향성, 미세구조 그리고 손상 내구성 사이 상호연관성에 대해 논의하였다.

• Journal of the Korean GEO-environmental Society
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• 제14권12호
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• pp.5-12
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• 2013

In this study, weathered granite model tests were performed to investigate the variation of volumetric water content and matric suction by the adsorption and desorption processes of artificial rainfall. It has been compared with numerical analysis in unsaturated condition. As the results, the behaviors of volumetric water content and matric suction were distinguished by the seepage distance separated into higher, middle and lower area, and the drainage layer located at the bottom of the experimental device. In the adsorption process, the instantaneously large change of matric suction and water content were related to the increase of permeability in soil. However, in the desorption process, the change of matric suction and water content were gradually small because of the decrease of permeability. The volumetric water content and matric suction showed the difference according to the seepage distance, however the typical characteristic curves were made by the adsorption and desorption processes.

• Journal of the Korean GEO-environmental Society
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• 제2권2호
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• pp.51-58
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• 2001

The primary objective of this paper was to study the seepage and the failure behavior of unreinforced and reinforced embankment, respectively. Experimental study was conducted to examine the infiltration characteristics. The embankment infiltration tests were conducted with water level condition(h=15cm, 25cm, 35cm), slope inclination(1:1.5, 1:2.0), and the rising velocity(1.25cm/min, 2.5cm/min), respectively. From the model test results, as the slope inclination is decreased, the rising velocity of seepage line increased with both reinforced and unreinforced embankment. With the unreinforced embankment, the rising velocity of water level was faster and the failure circle is lager than those of reinforced ones. And the reinforced embankment with geotextile was safer against seepage force than that of the unreinforced embankment.

• Geotechnical Engineering
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• 제7권1호
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• pp.53-68
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• 1991

This paper aims at the investigation of various seepage behavior when rainfall infiltarates into unsaturated ground and understanding of the mechanism for slope instability due to rainfall. For this purpose an experimental study is carried out for model slopes using the test equipment which can simulate various rainfall intensity. In addition, a numerical study is performed for the same dimension and boundary condition as the experimental model. From both the experimental test and numerical analysis the progress of wetting front with time, critical amounts of rainfall, and pore-water pressure development with time are know in detail and their effects on slope stability are described.

• Journal of the Korean Geotechnical Society
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• 제21권8호
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• pp.45-53
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• 2005

Shallow slope failures in residual soil during periods of prolonged infiltration are common over the world. Therefore, this study examines an approximate method to estimate the influence of infiltration on surficial stability of slopes by one-dimensional infiltration model. Modified GAML model based on the Green-Ampt model was extended to predict the infiltration behavior of two-layered slope. Then, the model has been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods in two-layered soil profile. The results obtained from the approximate method were compared with those obtained from numerical analyses. According to the results, with the use of properly estimated input parameters, the proposed method was found to give good results that agree reasonably well to those of the more rigorous finite element analyses.

• Journal of the Korean Geotechnical Society
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• 제30권3호
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• pp.17-28
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• 2014

In this study, the seepage behavior has been analyzed, which is the most important in determining the stability of the embankment. Large-scale embankment of weathered granite has been installed and TDR (time domain reflectory) sensors were used to detect the seepage lines. The TDR graphs could be separated into 3 sections, which are initial, unsaturated and saturated zones. TDR sensor can detect seepage line more easily than point sensor without analysis. Comparisons of the results of numerical analyses and the TDR sensors showed differences at water level rising condition, and then Comparisons of the results generally showed good agreement at another condition.

• Journal of the Korean Geotechnical Society
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• 제37권10호
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• pp.41-54
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• 2021

In this study, probabilistic steady seepage behavior of soil foundation beneath water retaining structures according to the location of cutoffs was studied. A Monte Carlo Simulation based on the random finite element method that considers the uncertainty and spatial variability of soil permeability was performed to evaluate the probabilistic seepage behavior. Fragility curves were developed by calculating the failure probability conditional on the occurrence of a given water level from the probability distribution obtained from Monte Carlo simulations. The fragility curve was prepared for the flow quantities such as flow rate through foundation soil, uplift force on the base of structure, and exit gradient in downstream to examine the reliability of the water retaining structure and the foundation soil. From the fragility curves, the effect of the location of cutoff wall on the reliability of water retaining structure and foundation soil according to the rise in water level was studied.