• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.5-18
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• 2005

In this study, the influence of progressive consolidation from the drainage boundary on the subsequent process of consolidation was investigated. Analytical theory and numerical program f3r consolidation of clayey soil were developed based on finite difference method, in which spatial variation of permeability and volume compressibility were implemented. And model ground with normally consolidated clayey soils and a vertical drain at its center were simulated. Various types of soils with different relations between coefficient of volume compressibility and permeability and void ratio were applied. Also numerical simulations based on the properties of the normally consolidated clay at Nakdong River basin and reconstituted kaolinite soil were performed to recognize its practical impact. Consequently, it is found out that retardation of consolidation induced by progressive consolidation is very important to understand consolidation behavior on field conditions and its effect is remarkable at the initial state of consolidation, and increases with plasticity index and applied load.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.43-51
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• 2011

Pile-supported embankment is one of the reinforcing methods to minimize damage due to the severe subsidence and lateral flow when soft clay ground is supported with embankment. pile-supported embankment mainly penetrates soft ground into the bearing stratum in order to support surcharge load which minimizes the subsidence and lateral flow due to the surcharge load. The aim of this research is to review quantitatively reinforcing effect of pile-supported embankment which is installed in soft clay ground. From the model test, it reproduced the ground movement with regard to the non-reinforced and reinforcing embankment-pile and also analyzed stabilizing effects of lateral flow due to the pile-supported embankment. With regard to the case of installing pile-supported embankment, its were analyzed stabilizing effects of lateral flow in cases of quick-load and slow-load to make different surcharge load.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.295-307
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• 2002

In the Nakdong River plain a very thick clayey soils are covered widely. Since the early 1990's, some huge reclamation projects have been performed for the development of industrial and residential complexes and so on. Despite a large number of soil investigations have been carried out for the projects, the geotechnical properties have never been elucidated well, so that the settlements of the ground due to the mischaracterized properties were greatly underestimated. Therefore, it has been needed to evaluate definitely the characteristics of the clayey soils, particularly for the compressibility characteristics to help understand the settlement behavior. For the compressibility characteristics of the Pusan clays, physical index and consolidation tests were conducted on the reconstituted and undisturbed samples. Using the result of physical index, the Pusan clays could be divided into two different units, which have different depositional environments. According to the concepts of Burland (1990) and Nagaraj et. al. (1990), the intrinsic state line and field compression curve of the Pusan clays could be established. It could be found from their concepts that the Pusan clays are under the cemented and young normally consolidated state and largely consisted of two units. The cementation of the clays was as well identified by compression index ratio (Tsuchida et. al.,1991) and sensitivity (Leroueil et. al.,1983).

• Journal of the Korean Geotechnical Society
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• v.17 no.3
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• pp.5-13
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• 2001

세립토에서의 세굴깊이의 발달은 일반적으로 조립토에서보다는 아주 천천히 진행된다. 조립토를 위해 개발된 방법을 시간효과와 무관하게 세립토에 적용한다면 세굴깊이가 과대하게 평가된다. SRICOS 방법은 점성토 또는 연암에 설치된 교각의 국부세굴깊이의 변화를 예측하기 위해 개발되었으며, 교량현장에서 채취한 흙에 대한 실험과 SRICOS 프로그램의 수행을 병행함으로써 적용된다. 본 논문에서는 SRICOS 방법을 간단히 설명한 후 프로그램의 세부적인 내용을 기술한다. 또한 이 프로그램을 이용하여 세굴에 미치는 각 매개변수의 영향을 평가하기 위해 실시한 매개변수 해석의 결과가 포함된다.

• Geotechnical Engineering
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• v.11 no.1
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• pp.41-50
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• 1995

In situ clay soils with Ko condition have anisotropic characteristics, varying the response according to the principal stress direction upon loading. But because of their practicality and simplicity, consolidated isotropic undrained compression tests are commonly used in practice to determine the behavior of cohesive soils. In this study to investigate the anisotropic characteristics and the effects of consolidation stress states on the response of normally consolidated clay soils during shearing, triaxial compression and extension tests after consolidating the undisturbed clay soil samples, which are obtained as a block sample to normalized consolidation states under isotropic or Ko state, were carried out. As a result of tests, the anisotropy of the undrained strength was confirmed. Comparing the soil responses between isotropic and Ko consolidation, the undrained strength by isotropic consolidation is overestimated because of its higher mean consolidation pressure. And isotropic consolidation reduces the anisotropy of soil response and influences on the stress-strain behavior and pore pressure response because the animotropic soil structure is partially collapsed during isotropic consolidation process. Also, OCR in overconsolidated soils is decreased by isotropic consolidatiorL Friction angle in eztension is higher than that in compression, but regression analysis shows that friction angle with cohesion in extension is almost the same as that without cohesion in compresslon.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.243-251
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• 2005

In the seismic design the pile foundation system of the buildings generally have been modeled to have a fixed end for its convenience and conservativeness. But it is necessary to consider the soil-structure interaction for more reliable design. In this study, the framed tube building and brace tube building with pile foundation system under earthquake were analyzed considering soil-structural interaction by 3 pile foundation modeling methods; fixed-end model, 6 springs model and p-y springs model. And 2 soil conditions were used in analysis. For each cases, displacements, drifts, maximum stress, periods and 1st mode mass participation ratios were compared.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.191-201
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• 2000

In this study, the earth retaining structure using a row of piles considering plastic flow of the ground is suggested for shallow excavation works instead of conventional anchored sheet-pile wall method in the marine clays with high groundwater level. The behavior of the earth retaining structure using a row of piles is precisely observed during excavation by inclinometer and piezometer installed in opposite to the excavation side. As a result of field measurement, it was found that the behaviors of the piles and the soil were influenced mainly by slope of excavation face, interval ratio of piles, fixity condition of pile head, and stability number, etc. The earth retaining structure using a row of piles is ascertained for workability, stability, and economical construction on the soft ground having no adjacent structures.

• Geotechnical Engineering
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• v.14 no.4
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• pp.61-76
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• 1998

Various kinds of reinforced soil methods have been developed by many researchers or companies for their economic merits mainly. These methods have generally used sandy soils which have high permeability as embanking or backfill material. That is because, if poor embanking materials, especially like a clayey soil which has very low permeability, are used in a reinforced soil embanking, and if excessive pore water pressure is produced by external factors, the friction resistance between reinforcing members and Boils decrease, as a result possible damage or collapse of the body of a reinforced embankment. In fact, clayey Boils can also be used as a embanking materials with reinforcement which has high permeable capacity, and are expected to be able to dissipate the excess pore water pressure effectively. In this study reinforcing effects have been examined through a serries of direct shear tests in which clayey soils are reinforced with nonwoven geotextiles of which permeability is very high and tensile strength is relatively weaker than geogrids which are usually used in reinforced soil wall. Even though such nonwoven geotextile are used as reinforcement of high saturated clayey soils. the test results show the possibility that nonwoven geoteztiles could be used as a reinforcement for reinforced soil walls effectively.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.23-33
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• 2000

인천국제 공항에 분포하는 해성세립토 지반에서 일련의 CPTU와 DMT를 실시하고 그결과로부터 구한 비배수전단강도($s_{u}$ ), 과입밀도(OCR), 압밀계수($c_{h}$) 등과 같은 지반 정수와 기존의 시험자료 등을 분석하여 두 시험 결과를 비교하였다. 이 분석에의하면, CPTU와 DMT 두시험은 모두 피에조콘 정수, $B_{q}$ )로 분류하여 점성토인 지반에서 보다 신뢰성이 높은결과를 주었으며, 또한 해석방법에 따라 지반정수 산정결과에 큰 편차를 보여, 적절한 해석방법의 선택이 신뢰성있는 지반정수의 산정을 위한 주요한 인자임을 알았다. 그리고, 소성적 성질이 낮은 세립토 지반에서의 CPTU와 DMT를 이용한 비배수전단 강도 또한 과압밀비의 산정은 상당한 오차를 유발할 수 있다고 판단되었다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.27-33
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• 2011

In general, the shear strength of a clay specimen under the direct shear test and the triaxial compression test increases with an increase in the shear rate. This study investigates the effects of shear rate and silt content on the stress-strain behavior of remolded Gwangyang clay, by changing the shear rate and the silt content. Based on the results of the triaxial compression tests, the equi-strain line of remolded Gwangyang clay shows initially positive slope and then becomes flat at certain strain level. As the strain level where the equistrain becomes flat is different depending on the soil with different silt contents, this can be considered as the inherent property of soil.