• 한국농공학회논문집
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• 제55권2호
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• pp.87-95
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• 2013

The aim of this study is to examine the behavior of reservoir fill dam with the water level raising by use of the centrifugal model test and the numerical simulation. In this study, LIQCA2D-SF based on the cyclic elasto-plastic constitutive model proposed by Oka et al. (1999) is applied for numerical simulation. In order to investigate the displacements and the pore water pressures in the fill dam due to the water level raising velocity, three model tests in centrifugal field of 50g for fill dams were conducted. A comparison between the test result and the simulation result has provided the influence on the displacement and the pore water pressure of the fill dam with increasing up of the water level.

• 한국지반공학회논문집
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• 제20권6호
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• pp.5-10
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• 2004

일반적으로 일차원 압밀상태에 있는 정지토압계수 $K_0$값은 삼축시험에서 구해지지만, 압밀중의 간극수의 흐름이 방사류이고, 공시체의 변형이 3차원적이므로, 얻어진 값의 신뢰성에는 의문이 있다. 여기서는, 일차원 압밀시험기를 개량하여, 압밀링 중앙높이에 배치한 압밀링 요소를 토압감지부로 하며, 감지부 중앙에서는 간극수압을 측정하였다. 내경 6cm의 압밀링은 부동(浮動)링 형식으로 높이 4cm의 공시체 중앙높이가 항상 같은 위치를 유지하는 구조이다. 직경 6cm의 공시체와 샘플링후 시료변형을 고려한 압밀링 내경보다 직경이 약간 작은 공시체에서 얻은 압밀종료시의 $K_0$값은 공시체직경과 압밀압력에 상관없이 거의 0.5를 나타내었다.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.24-35
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• 2017

본 논문은 하천 제방의 침투방지공법으로 일본 미쓰야마 하천 국도 사무소에서 제시한 월륜 공법에 대한 효용성을 연구한 것으로, Hydraulic well의 현장 적용성과 시공성 개선, 침투압 분포 특성을 파악하기 위하여 대형 제방실험과 침투 해석을 수행하였다. 대형제방실험의 방법은 제외지 수위를 재현하여 제방을 포화시킨 후 제방의 간극수압계 변화를 감지, hydraulic well의 내부 수위를 0.1 m ~ 0.7m로 변화하고 이때 간극수압계를 통해 측정된 간극수압을 비교하여 침투압의 변화를 확인하였다. 대형 제방실험은 hydraulic well의 설치 지점에 따라 두 가지 방법으로 수행하였다. 대형 제방실험결과, hydraulic well의 내부 수위 변화에 따라 최대 37%의 침투압 저감 현상이 발생하는 것으로 평가되었다. 대형 제방실험과 침투 해석의 간극수압을 비교한 결과 거의 유사한 경향이 나타났다. hydraulic well의 내부 수위 변화와 산정된 간극수압의 변화도 비슷한 양상을 보였으나, 심도가 깊어짐에 따라 대형 제방실험결과보다 침투 해석의 간극수압이 더 크게 산정되었다.

• 한국농공학회지
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• 제38권1호
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• pp.79-89
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• 1996

It is expected that the soil hehaviours in the seahed subjected to cyclic wave loads are much different from that on the ground Cyclic shear stresses developed below the ocean bed as a result of a passing wave train may progressively build up pore pressure in certain soils. Such build-up pore pressure may be developed dynamic behaviour such as liquefaction and significant deformation of the seabed. Currently available analytical and testing methods for the seabed subjected to cyclic wave loads are not general. The purpose of the study are to provide a test method in laboratory and to analyse the mechanism of wave-induced stresses and liquefactions potentials of the unsaturated silty marine sand. It is showed that the test set-up made especially for this study delivers exactly oscillatory wave pressures of the form of sine function. Laboratory test results defining the cyclic shear strength of the unsaturated porous medium that is homogenously sedimented. It is understood that the pore water pressure due to induced-waves is not accumulated as the wave number increases but reveals periodical change on the still water surface. The magnitude of the pore water pressure tends to be attenuated radically with a certain time lag under the action of both high and low waves as depth increases.

• 한국농공학회지
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• 제45권4호
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• pp.126-136
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• 2003

The B value on the saturated soil is commonly known as the amount of 1. Usually this concept is consistent with the condition that effective stress is equal to zero, but it was reported in some literatures that the B value was less than 1 in spite of saturated condition in the test of very stiff material such as rock and quasi-stiff material on which the stiffness can be mobilized because of effective stress not equal to zero. In this study the B value was measured on various effective stress conditions on normally consolidated clay. The test results in the B value less than 1 in spite of perfect saturation. The measured excessive pore water pressure was not only smaller than the change of the total stress, but also the function of time on clay.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.38-44
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• 2010

Shaking table tests were performed to reproduce the dynamic behavior of estuary barrage and its subbase soil which can be potentially damaged during earthquake loading. For understanding the vibration effect to the ground during earthquake, the model was formulated with 1/300 scale of prototype estuary barrage and subbase soil. Scott and Iai(1989) proposed the law of the similarity for similar experimental conditions. The laboratory model shaking table test was conducted under the vibration condition of simulated earthquake of 0.154g. The horizontal displacement on the structure was measured during the shaking table test. The pore water pressure was also monitored for the underground layers of soil. The field horizontal displacement and the pore water pressure can be predicted by using the results of the laboratory shaking table test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1204-1211
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• 2008

Compression index is one of the important characteristic numbers in soft soil engineering. Since 1940's, many researchers have suggested various practical solutions to define the compression index of clay using other soil properties. But, these results are only can give us an outline of soft soil behavior. In this study, the relationships between pore water pressure dissipation test results and compression index were suggested using comparison results of both tests. This relationships are based on basic concept of consolidation phenomena, essential difference between pore water pressure dissipation test and consolidation test, and disagreements between theoretical time factor and real time factor. To identify proportional factor of proposed equation, Geotechnical investigation results of Kwang-Yang(KY) site and Busan New Port(BN) site were used. The proportional factor was 0.0031 from 20 to 50% of consolidation rate where correlation parameter($R^2$) is 0.9051.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.140-147
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• 2003

There are many problems in the prediction of soil dynamic behaviors because undrained excess pore water pressure builds up and then the strain softening behavior is occurred simultaneously. A few analytical methods based on the dynamic constitutive model have been proposed but the model hardly predict the excess pore water pressure directly. In this study, the verification on the disturbed state concept (DSC) model, proposed by Dr, Desai was performed. Some laboratory tests such as conventional triaxial tests and cyclic triaxial tests were carried out to determine DSC Parameters and then disturbance values are determined by the proposed equation. Through this verification, it is proved that the disturbed state concept can express reliably the soil dynamic characteristics such as excess pore water pressure and strain softening behavior. It is also found that the critical disturbance which is determined at the minimum curvature of disturbance function can be a the specific index.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.107-114
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• 2003

There are many problems in the prediction of dynamic behaviors of saturated soils because undrained excess pore water pressure builds up and then the strain softening behavior is occurred simultaneously. A few analytical constitutive models based on the effective stress concept have been proposed but most models hardly predict the excess pore water pressure and strain softening behaviors correctly In this study, the disturbed state concept (DSC) model proposed by Dr, Desai was modified to predict the saturated soil behaviors under the dynamic loads. Also, back-prediction program was developed for verification of modified DSC model. Cyclic triaxial tests were carried out to determine DSC parameters and test result was compared with the result of back-prediction. Through this research, it is proved that the proposed model based on the modified disturbed state concept can predict the realistic soil dynamic characteristics such as stress degradation and strain softening behavior according to dynamic process of excess pore water pressure.

• Geomechanics and Engineering
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• 제1권1호
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• pp.35-52
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• 2009

A significantly thick zone of steep slopes is commonly encountered above groundwater table and the soils within this zone are unsaturated with negative pore-water pressures (i.e., matric suction). Matric suction contributes significantly to the shear strength of soil and to the factor of safety of unsaturated slopes. However, infiltration during rainfall increases the pore-water pressure in soil resulting in a decrease in the matric suction and the shear strength of the soil. As a result, rainfall infiltration may eventually trigger a slope failure. Therefore, understanding of shear strength characteristics of saturated and unsaturated soils under shearing-infiltration (SI) conditions have direct implications in assessment of slope stability under rainfall conditions. This paper presents results from a series of consolidated drained (CD) and shearing-infiltration (SI) tests. Results show that the failure envelope obtained from the shearing-infiltration tests is independent of the infiltration rate. Failure envelopes obtained from CD and SI tests appear to be similar. For practical purposes the shear strength parameters from the CD tests can be used in stability analyses of slopes under rainfall conditions. The SI tests might be performed to obtain more conservative shear strength parameters and to study the pore-water pressure changes during infiltration.