• Journal of the Korean Geotechnical Society
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• v.28 no.12
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• pp.65-76
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• 2012

In this study, probabilistic analysis of seepage through a two-layered soil foundation was performed. The hydraulic conductivity of soil shows significant spatial variations in different layers because of stratification; further, it varies on a smaller scale within each individual layer. Therefore, the deterministic seepage analysis method was extended to develop a probabilistic approach that accounts for the uncertainties and spatial variation of the hydraulic conductivity in a layered soil profile. Two-dimensional random fields were generated on the basis of the Karhunen-Lo$\grave{e}$ve expansion in a manner consistent with a specified marginal distribution function and an autocorrelation function for each layer. A Monte Carlo simulation was then used to determine the statistical response based on the random fields. A series of analyses were performed to verify the application potential of the proposed method and to study the effects of uncertainty due to the spatial heterogeneity on the seepage behavior of two-layered soil foundation beneath water retaining structure. The results showed that the probabilistic framework can be used to efficiently consider the various flow patterns caused by the spatial variability of the hydraulic conductivity in seepage assessment for a layered soil foundation.

• Journal of the Korean GEO-environmental Society
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• v.16 no.8
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• pp.45-49
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• 2015

Using 2D numerical analysis that covers the largest section of the dam body, a process is generally performed when evaluating its stability against seepage. The quantity of seepage is first obtained by assuming that its bottom topography is in the simple form of a rectangle, it is then calculated by reflecting its sectional shape during this process of analyzing the seepage quantity. Considering that various forms of dams are being constructed on various types of ground, thanks to more recent technological advances, it is judged more appropriate to draw a conclusion by means of the results on reflecting the realistic shape and topographical conditions of the dam body through 3D numerical analysis. Therefore, this study intends to present a method designed to carry out safety management by evaluating the correct quantity of water leakage that passes only through the dam body, having excluded other factors that include the amount of rainfall through the 3D FEM analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1507-1512
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• 2007

우리나라에서 발생하는 사면재해는 7월${\sim}$9월, 즉 태풍 및 집중호우가 발생하는 시기에 대부분 나타나며 이를 통해 강우는 사면재해를 유발시키는 가장 중요한 요인임을 알 수 있다. 사면재해는 매우 짧은 시간에 일어나며, 큰 피해를 발생시키는 특징을 가지고 있다. 따라서 강우 발생시 사면의 안정성을 검토하는 경우에 보다 합리적으로 강우의 특성을 적용할 수 있다면 강우로 인해 발생될 수 있는 사면재해를 미리 예측하고 이에 대비할 수 있을 것이라 판단된다. 사면 해석시 강우에 대한 인자는 강우강도를 적용하며, 이는 사면에 거의 모든 강우가 침투된다고 가정하여 지하수위를 산정하지만, 이는 유출을 고려하지 않은 결과이다. 본 논문에서는 지하수위 예측 프로그램인 SEEP/W 프로그램을 이용하여 침투량에 따른 사면의 지하수위 변화를 예측해 보았다. 이를 위해 기상청 산하 서울 지점의 1961년부터 2005년까지의 시간 강우량 자료를 이용하여 확률강우량을 산정하였고, 산정된 값을 해석적 침투모형에 의하여 침투량을 계산하여 합리적으로 침투량을 해석단면에 적용하여 지하수위가 시간에 따라 어떻게 변화하는 지를 연구하였다.

• Journal of the Korean Geotechnical Society
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• v.39 no.10
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• pp.19-26
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• 2023

This research aimed to predict the seepage rate in the base rocks of a concrete face rockfill dam (CFRD) by conducting numerical analysis under various conditions. We examined the relationship between basic grouting and seepage, emphasizing the significance of the permeability coefficient of the grouting material and the rock. Moreover, we observed a decrease in seepage with an increase in the cross-sectional area of the dam. The results of this study provide essential input factors and outcomes of numerical analysis, incorporating various parameters, to inform the design phase. Additionally, our findings offer a dependable approach for calculating a reasonable seepage rate during both operational and maintenance phases.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.301-310
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• 1999

In this paper a numerical model and two analytical models in the hydraulically connected stream-aquifer system were analyzed to compare the induced infiltration rate curves derived from each model. And we also examined the effects of anisotropy of hydraulic conductivity and the direction of the ambient ground water flow on the quantification of the induced infiltration rate. The induced infiltration rate curve determined by models is very simple and useful for estimating the induced infiltration rate since it contains only four physical variables such as the induced infiltration rate, the pumping rate, the distance between the pumping well and the stream, and the ambient ground water flow rate. Under the conditions tested in this paper the induced infiltration rate curves resulted from the Wilson's analytical model and FEWA numerical model were in good agreement, and the anisotropic ratio of hydraulic conductivity was evaluated as a physical factor which influences the behaviour of the induced infiltration rate curve. The methods and results of the paper might Icad to improve the understanding of the induced infiltration phenomenon and can be applied to the planning and disign of pumping well and the optimal determination of the induced infiltration rate and pumping rate for water quality management of the water supply wells.

• Computational Structural Engineering
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• v.11 no.4
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• pp.147-154
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• 1998

강체 충격자가 납 표적에 33m/s ∼ 141m/s의 속도로 충돌할 때의 침투특성을 연구하기 위하여 Jognson 이론식을 이용한 이론해석과 AUTODYN 코드를 이용한 수치해석 및 실험장치를 이용한 실험측정을 실시하고 그 결과들을 비교 분석하였다. 실험장치로는 가스압력식 발사장치를 설계 제작하였으며, 실험용 충격자로는 충돌부위 형상이 반구형인 반구형 충격자와 원추형인 원추형 충격자 2종류를 사용하였다. 또한, 납재료에 대한 동적 유동응력을 얻기 위하여 홉킨스 압력봉실험을 수행하였다. 침투특성에 관한 연구결과, 이론적 해석결과는 저속 충돌범위(반구형 충격자 : 53m/s, 원추형 충격자 ; 73m/s)에서 실험결과치와 93%이상 잘 일치하였으며, 수치해석결과는 전체적인 충돌속도 범위에서 반구형 충격자인 경우 73%이상, 원추형 충격자인 경우 86%이상 일치하였다.

• Geotechnical Engineering
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• v.35 no.1
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• pp.14-22
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• 2019

• Journal of the Korean Geotechnical Society
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• v.34 no.10
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• pp.51-60
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• 2018

Recently, a cylindrical cut-off wall was proposed as a new technology for temporary offshore works. The cut-off wall has a cylindrical shape, so seepage analyses are necessary to analyze the effect of wall shape. In this study, a numerical analysis was performed to investigate the seepage discharge inside cut-off walls. The numerical modeling was verified by comparing with the theoretical solution for the cofferdam with double sheet piles. Two different flow conditions were compared between 2-dimensional flow and axisymmetric flow. The results showed that the discharge of the axisymmetric flow was about 1.55 times larger than that of 2-dimensional plain flow. A parametric study was carried out by varying wall radius, penetration depth of the wall, and total head difference between in and outside of the wall. The discharge decreased with the increase of the penetration depth and the wall radius. Finally, the design equations were suggested to determine the discharge for the preliminary design of the cylindrical cut-off wall.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.247-256
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• 2012

The purpose of this study is to decide the permeability and the rate of flow in a way of both site investigation and backward analysis and the most reasonable numerical analysis by performing a seepage model test for measuring the deformation swept volume of the embankment body in order to review a stability of the sea dyke being composed of multi-layers depending on variation of infiltration. As a result of the review, it could be forecasted that sweeping loss would be taken place at the boundary between bed protection works and embankment materials of the sea dyke due to a permeability difference of the multi-layered bed foundation structures and the sea dyke deformation would be occurred as a result thereby. As result of a numerical analysis for the seepage model test, it could be observed that critical velocity method was found to be smaller than the numerical analysis value but its tendency was similar and therefore it was judged that this method could be applied for the actual cross section.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.13-27
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• 2018

To study how stable the rubble mound breakwaters are, one can look to the research of wave induced seepage flow through the pores of the rubble mound. Seepage flow is generally generated by the difference between the water level around the breakwater during a typhoon. The existing stability analysis method of the rubble mound is the static analysis which simply considers the force equilibrium taking into account the horizontal force acting on the concrete block induced by a wave (calculated by Goda equation) and the vertical force induced by the weight inclusive of the concrete block, quarry run, filter, and armor layer above the slipping plane. However, this static method does not consider the wave-induced seepage flow in the rubble mound. Such seepage may decrease the stability of the rubble mound. The stability of a rubble mound breakwater under the action of seepage was studied based on the results of CFD software (OpenFOAM) and Limit Equilibrium Method (GeoStudio). The numerical analysis result showed that the seepage flow decreased the stability of the rubble mound breakwaters. The results of the numerical analyses also revealed the stability of the rubble mound was varied with time. Especially, the most critical state happened at the condition of overtopping the concrete block, acting strong uplift pressure raising along side and underneath the concrete block, and generating high pore pressure inside rubble mound due to seepage flow. Therefore, it may be necessary to conduct a dynamic analysis considering the effect of wave-induce seepage flow together with the static analysis.