• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.33-39
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• 2018

In this study, important characteristics were identified for the Geosynthetic-soil interface using overburden pressure and saltwater and fresh water to evaluate silt shear behavior of the Geosynthetic-soil interface. In addition, waste landfill can secure spaces for waste disposal in the sea and this spaces can be used for additional facilities which will be necessary in the future. Analysis of behavior characteristics on interface of Geosynthetic-soil shows that, if analyzed using standard consolidometers, the consolidation stress of fresh water increased significantly more than saltwater. When analyzed using cyclic shear apparatus, saltwater and freshwater in both conditions, the displacement value increases as the wire gauges become closer to the lower module, and the shear fracture tends to occur radically under saltwater conditions than fresh water. Therefore, seawater, fresh water that act on the interface of geosynthetic-soil, and installation of facility using geosynthetic should be considered as important parameters that are essential for the dynamic design factor of the water controlling facility.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.79-89
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• 2008

In this study, a series of undrained cyclic triaxial tests were performed with three different consolidation stress ratios ($K_c$=1.0, 1.5, 2.0) to investigate the undrained shear strength characteristics of sands with respect to the amount of contained silt located around the basin of Nak-dong River. The test results show that the more the sand has silt, the lower is cyclic shear stress ratio (CSR) in all $K_c$ and that the higher $K_c$ goes, the larger CSR decreases due to the increase of contained silt. The excessive pore pressure caused during shearing has an influence on the decrease of CSR by the high initial pore pressure in proportion to the amount of contained silt regardless of the $K_c$ value. After consolidation, the analysis of the skeleton void ratio of the sample reveals that the main cause of the decrease of CSR as well as the increase of the initial excessive pore pressure is the increase of the skeleton void ratio in proportion to the amount of contained silt.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.181-190
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• 1995

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.42-58
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• 2000

본 연구의 목적은 연약지반의 압밀계수 측정에 있어 Piezocone 관입시험을 이용할 때 관입시험자체의 정확성과 시험결과들에 미치는 여러 가지 지반공학적 영향요소들을 고려하려는데 있다. 본 연구의 연구실험방법으로는, Piezocone 관입을 위한 연약모형지반 조성을 위하여 초대형 Slurry Consolidometer에 Free Stress 상태의 Slurry를 45일간 압밀시킨 후 Automatic Computer Control Calibration Chamber (LSU/CALCHAS; Louisiana State University Calibration Chamber System)에 옮긴후 다시한번 압밀시키는 Two-Stage Consolidation Method를 사용하였다 동시에 연약모형지반내에 8개의 Piezometer를 설치하여 Piezocone 관입시 유발되는 지반 내에서의 과잉간극수압의 변환을 측정하였다. 총 25개의 Piezocone 시험중 4개는 Standard 10$\textrm{cm}^2$ Piezocone이고, 나머지 21개는 Miniature Piezocone이 사용되었다. 모형지반은 여러 가지 Boundary Condition들과 Stress Condition 그리고 Stress History등을 고려하여 조성되었다. 또한 Dissipation Test직후의 압밀특성을 확인하기 위하여 0.01초당 한 개이상의 실측점을 측정할 수 있는 Digital-Oscilloscope를 이용하였다. 특히 Dissipation Test, 즉시 Piezocone의 Filter Element에 잡히지 않는 과잉간극수압의 Initial Drop 존재에 관한 기존의 추측을 실제 실험치로 확인할 수 있었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.211-216
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• 2003

굴폐각은 굴양식 후 남는 것으로 남해안에서 주로 집중적으로 발생하는데 연간 28만톤의 발생량 중 상당양은 폐기물로 계속 누적되고 혹은 불법매립되어 환경오염 문제까지 발생시키고 있다. 본 연구에서는 산업폐기물로 분류되는 굴패각을 지반공학 분야에서 활용하기 위한 대안으로 해성점토와 혼합하여 매립재료로써의 적용성을 평가하기 위하여 대형 압밀기를 이용하여 실험을 실시하고 이를 토대로 기초자료를 획득하고자 하였다. 원형의 굴패각을 파쇄하여 입도별로 분류하고 이중 사질토 입경 크기의 재료에 대한 기본 물성치를 평가하고 지반 재료로써의 적용성를 분석하였다. 해성점토 내의 굴패각입자의 혼합비를 변화시켜 만들어진 혼합토에 대한 압밀 실험 결과 굴패각의 혼합율이 증가할수록 체적변화율이 작게 되고, 침하 속도는 빠르게 증가함을 알 수 있었다. 이는 압밀응력의 일부를 굴패각 입자의 골격구조가 부담함으로써 실제 점토부분에 작용하는 압밀응력은 굴패각 혼합율이 증가할수록 작아지는 것으로 판단된다.

• Structural Engineering and Mechanics
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• v.11 no.5
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• pp.547-564
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• 2001

The numerical formulation of a two-phase interface element appropriate for porous lining system is presented. The formulation is isoparametric and can be applied both for 2-D and 3-D analysis. Biot's theory is utilized as the basis for the development of the element constitutive theory. In order to be capable of simulating the reinforcing characteristics of some geotextiles utilized as lining system, a reinforcement component has also been implemented into the formulation. By employing this specially developed interface finite element, the influence of soil consolidation on the stress distribution along the lining system of a reservoir and a landfill has been investigated.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.231-238
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• 2000

Sand piling method is one of the most widely used methods to improve soft soils. There are several methods to install sand piles, but driven pile method is considered as one of the easiest method. This method simply pushes down the sand piles into soft soils, so that the excess pore pressure would be generated if the soil is saturated. This pore pressure acts as consolidation load. If the amount of sand pile induced pore pressure can be predicted in reasonable ways, the effects of sand piling to improve soft soils would be predicted, and the height of preload can be reduced. In this article, sand pile induced excess pressure was predicted by cavity expansion theory, and the predicted values were compared with the field measured values. The results showed fair agreements between the measured and the predicted excess pore pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.960-963
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• 2010

In recent days, the development project for industry or housing complex at west coast of Korea is on an increasing trend. the design of soft ground is necessarily required. So, the evaluation of consolidation characteristics for soft ground is very important in design and construction. Especially, the correct evaluation of preconsolidation pressure or OCR for given soft ground is essential at the west coast that has a large tidal range, since it affects the settlement of soft ground. In this study, various methods determining preconsolidation pressure were carried out to investigate the application of each method. The preconsolidation pressure that evaluated from the results of conventional consolidation tests on the songsan clay were compared.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.123-129
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• 1998

Compressibility and permeability properties are the most important input parameters necessary to assess the suitability of core materials in seepage control system construction. To achieve this objective, an experimental investigation was conducted in the laboratory. For the bentonite-soil/sand mixes, consolidation and permeability tests were carried out in the conventional consolidation cell, 6Omm in diameter and 2Omm in height, was modified to perform a falling head type permeability test. From the results, the normalized relationship with respect to void ratio at liquid-limit state $(e_L)$, and the changes of compressibility and permeability for various bentonite-soil/sand mixes were presented. This approach will be helpful in proportioning mixes and predicting corresponding changes in engineering behavior. And it is possible to proportion a mix to arrive at the required compressibility without affecting the permeability.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.111-114
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• 2003

Due to the increasing interest in preserving environment, many environmentally friendly canal consolidation methods has been developed. Those methods, however, tend to focus more on the scenery than on the control of water. Thus, the safety of such methods are need to be studied more profoundly. In this study, the hydraulic examination of applied environmentally friendly methods using HEC-RAS model considering roughness coefficient and shear force in a canal is done to present the hydraulic safety of each methods. Further more, vegetations distribution characteristics and maintenance methods of channel are investigated.