• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.709-718
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• 2008

Developed is a chloride penetration analysis program in which changes of environmental conditions such as temperature, humidity and external chloride concentration, and the diffusion, convection and binding of chlorides are considered. In order to consider the changes of environmental conditions, analyses for temperature and moisture distribution are implemented simultaneously, and variation of diffusion coefficients due to temperature, humidity and age is also considered. By comparing the calculated total chloride contents with some experimental data, it has been confirmed that the proposed analysis program can trace measured chloride distribution well. Also, through some example analyses, the mechanism of accumulation of chlorides at near surface and acceleration of corrosion of steel reinforcement in case that the moisture distribution changes according to repeated drying and wetting cycles have been verified.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.119-131
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• 2005

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. The behavior of dam such as seepage rate and the pore water pressure distribution is different according to the unsaturated hydraulic properties, but nevertheless simply assumed properties have been used due to insufficient data from domestic soils. In this paper, the effect of unsaturated hydraulic properties on the behavior of dam was studied through a series of numerical analyses, and then the results were discussed. It is observed that water table moves at a (aster rate, as the values of unsaturated soil parameter a and n increase. The value of m showed opposite trend. The sensitivity calculated using the approximation form showed maximum values near the water table. And the value of n that is related to the slope of soil water characteristic curve gives greatest influence on the change of sensitivity with time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.515-524
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• 2015

The number of occurrence of differential settlement and track irregularity at track transition zone recently comes to increase, which leads to frequent maintenance activities that have an impact on train operation. Such track transition zone damages are attributed to the change of mechanical properties of fill materials due to environmental factors such as rainfall and freeze, and thaw. Consequently, this study attempts to establish the soil water characteristic curve (SWCC) of fill materials, and conduct seepage analysis to assess the distribution of degree of saturation (DOS) for track transition zone in case of rainfall. The SWCC of fill materials was successfully obtained using filter paper test method. The results of seepage analysis revealed that rainfall intensity, the slope of backfill, backfill condition (fill or cut), and SWCC are significantly influential in controlling the distribution of DOS.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.29-38
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• 2011

The unsaturated layers by rainfall infiltration are not properly reflected in construction codes to do slope design. The objective of this paper is to analyze the slope behavior according to the saturation layer increase resulted from the rainfall infiltration, to do that the laboratory slope model apparatus was adopted. From the model apparatus, the variation of water content and strength parameters of the model slope were analyzed. The safety factors of model slope was decreased, if saturation layer was increased from 3.0m to 4.5m, which means ground water level 3m selected from construction codes makes higher safety level. Also, if the ground water level is located in soil surface, the lower safety level will show up. Therefore, to make the proper slope design, the experiments and analysis of variation of saturation layer is needed.

• Journal of the Korea Institute of Building Construction
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• v.22 no.1
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• pp.1-10
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• 2022

Recently, due to the frequent occurrence of localized torrential rains and heat waves caused by abnormal climates. For this reason, it is necessary to develop an economical and eco-friendly rainwater detention facility that can secure the groundwater level through rainwater detention as well as flood prevention against concentrated rainfall by simultaneously implementing rainwater permeation and storage. In this study, the structural safety of an eco-friendly rainwater infiltration type detention facility made using eco-friendly inorganic binders including red clay was examined. Static analysis considering the constant load and additional vertical load and dynamic analysis considering the seismic spectrum were performed. As a result, it was found that the eco-friendly prefabricated rainwater infiltration type detention facility developed in this study has a maximum stress of about 68.1% to 75.4% and a maximum displacement of about 0.9% to 9.6% under the same load and seismic conditions compared to the existing PE block rainwater detention facility. It was confirmed that the eco-friendly prefabricated rainwater infiltration type detention facility secured excellent structural stability.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.5-15
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• 2013

In this paper, the unsaturated slope stability analysis considering suction stress (Lu and Godt, 2008) was introduced and the results applied for a certain sand slope were analyzed. The unsaturated slope stability analysis considering suction stress can analyze both conditions of steady infiltration and no infiltration, and it can estimate the safety factor of slope as a function of soil depth. Also, the influence of weathering phenomenon at a certain depth from the ground surface can be considered. The stability analysis considering suction stress was applied to the unsaturated infinite slope composed of sand with the relative density of 60%. The suction stress under no infiltration condition was affected by ground water table until a certain influencing depth. However, the suction stress under steady infiltration condition was affected by seepage throughout the soils. Especially, the maximum suction stress was displayed around ground surface. The factor of safety in the infinite slope under no infiltration condition rapidly increased and decreased within the influence zone of ground water table. As a result of slope stability analysis, the factor of safety is less than 1 at the depth of 2.4 m below the ground surface. It means that the probability of slope failure is too high within the range of depths. The factor of safety under steady infiltration condition is greater than that under no infiltration condition due to the change of suction stress induced by seepage. As the steady infiltration rate of precipitation was getting closer to the saturated hydraulic conductivity, the factor of safety decreased. In case of the steady infiltration rate of precipitation with $-1.8{\times}10^{-3}cm/s$, the factor of safety is less than 1 at the depths between 0.2 m and 3 m below the ground surface. It means that the probability of slope failure is too high within the range of depths, and type of slope failure is likely to be shallow landslides.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.11-22
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• 2014

In this study, numerical analyses and model tests were conducted to figure out the behavior of a slope reinforced by upward drainable soil nails during rainfall. The model tests were carried out on both reinforced and unreinforced slopes. To verify the results of the tests, seepage analyses were performed and compared with the test results using a commercial program, SEEP/W. The results showed that the numerical analyses have in overall a good agreement with the experiments in the variations of ground water level and pore water pressure even though there is some time delay for the experiment before the changes in the ground water level and pore water pressure after rainfall are observed, while the numerical analyses not.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.51-64
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• 2000

This paper presents a procedure of calculating a safety factor of the unsaturated slope suffering from the rainfall infiltration. The process of infiltration into a slope due to rainfall and its effect on the behavior of the soil slope are examined by using a two dimensional finite element flow-deformation coupled analysis. A factor of safety is calculated at various elapsed times after the commencement of rainfall as in the following procedure. First, stresses are estimated at each Gaussian point from the coupled finite element analysis. Then, the global stress smoothing method is applied to get a continuous stress field. Based on this stress field, a factor of safety is calculated for a specified slip surface by a stress integration scheme. Then, a search strategy is used to find out a critical slip surface which is associated with the minimum factor of safety. Some numerical examples are analyzed in order to study the effect of hydraulic conductivity on the slope stability during rain-induced infiltration. According to the results, local failure zone can be formed near the slope surface due to inhomogeneous distribution of hydraulic conductivity If the failure zone is once formed, then the region extends until a large amount of slide activates. Therefore the local failure can be neglected no longer in the stability analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.264-264
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• 2021

해수면 상승 및 인간의 활동으로 인한 해수 침투 영향 반경의 예측 및 모의에 대한 연구는 활발히 진행되고 있으며, 해수 침투 피해를 완화하기 위한 다양한 대응 방안이 시도되고 있다. 하지만 해수 침투 피해 대응 방안 등을 효율적으로 사용하기 위해서는 해수 침투 피해가 가장 활발히 일어나는 지역을 선정하고, 지역 특성에 맞는 대응 방안을 선정하는 과정이 필요하다. 기존의 해수침투 취약성 평가의 방법은 대수층 매개변수의 불확실성, 자료의 결측이 빈번하게 발생하고 있다. 또한, 평가 인자에 대한 자료 수집이 어렵고, 대수층에 대한 매개변수의 불확실성으로 직관적인 평가가 어렵다. 본 연구에서는 서해안의 도서지역을 제외한 연안지역을 대상으로 해수침투 취약성 평가 기법을 개발하였다. 해수침투에 대한 직관적인 해석을 위해 직접적인 영향을 미치는 수문 성분 중 해수면, 지하수위, 함양량, 지하수 이용량을 지표로 선정하고, 행정구역 단위로 자료를 수집하였다. 각각의 자료에 대한 평균, 기울기를 이용하였다. 각각의 인자에 대해서 객관적 가중치 산정 방법인 엔트로피 방법을 이용하여 가중치를 결정하였다. Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)를 이용하여 가장 취약한 지역을 선정하였다. 객관적 가중치 산정 방법을 이용하여 자료를 통해 직접적인 평가 가능하며, 추세 분석을 통해 앞으로의 해수침투 취약성에 대한 전망도 가능하다. 평가 결과를 이용하여 해안의 지하수자원의 지속가능한 운영 관리를 위한 자료로 활용할 수 있을 것이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1201-1211
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• 2014

The purpose of this paper is to present the aperture cut-off filter for reduction of electromagnetic field penetration through a slot in conducting screen. The reduction characteristics of electric field penetration by the aperture cut-off filter are considered. In order to establish the concept of the aperture cut-off filter, the integral equation on the slot aperture field distribution is derived and solved by method of moments, and the reduction characteristics of penetration electric fields for the incident plane wave are calculated. The numerical results showed that the aperture cut-off filter for reduction of electric field penetration through the slot can be realized. To check the validity of the concept of an aperture cut-off filter and the theoretical analysis, the calculated electric field penetration of the metallic wall with narrow slot were compared with the experimental results.