• 대한토목학회논문집
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• 제31권1C호
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• pp.11-17
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• 2011

본 연구는 백마강 모래의 상대밀도를 25%, 50%, 80%, 100%로 각각 변화시켜 등방압축-팽창시험과 구속압력을 달리한 일련의 배수삼축시험을 하였다. 그리고 이 시험자료를 이용하여 회귀분석을 근거로 상대밀도의 변화에 따른 Lade의 단일항복면 구성모델의 토질매개변수의 변화 특성을 알아보았다. 그 결과 탄성성분을 나타내는 토질매개변수 Kur과 n은 상대밀도의 변화에 따른 영향이 미소하고 파괴규준, 경화함수, 소성포텐셜에 관련된 토질매개변수는 상대밀도의 증가에 따라 선형적인 증 감현상을 보이고 있다. 그리고 항복함수에 관련된 토질매개변수 h와 ${\alpha}$는 상대밀도에 따른 변화가 미세하고 파괴규준에 관련한 토질매개변수와 관련성이 매우 높아 파괴규준, ${\eta}_1$에 관한 식으로 대체할 수 있으며, 이 식을 이용하여 수치해석 한 결과 양호하게 예측하고 있다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.109-116
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• 2002

Since experimental evaluation of underground RC structures considering interaction with surrounding soil medium is quite difficult to be simulated, the evaluation for the underground RC structures using an analytical method can be applied very usefully. For underground structures interacted with surrounding soils, it is important to consider path-dependent RC constitutive model, soil constitutive model, and interface model between structure and soil, simultaneously. In this paper, an elastoplastic interface model which consider thickness of interface is proposed and applied for the analysis considering the interaction. Failure mechanism of underground RC box of two story and two box subway station under seismic action is obtained and the effects of ductility of intermediate column to entire underground RC system are investigated through analysis.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.351-356
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• 1999

An elasto-plastic constitutive model was Proposed, in which the behavior at small-to-large strain level can be modeled. From a mathematical approach it was proved that the model includes the previous successful models. The experimental results of a series of resonant column tests, torsional shear tests and triaxial tests were verified and as a result the proposed model could predict small-to-large strain behavior more consistently and accurately than the hyperbolic model and the Ramberg-Osgood model for a weathered granitic soil.

• Geomechanics and Engineering
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• 제28권1호
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• pp.89-105
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• 2022

The behavior of the soil subgrade is complex and irregular against loads. When modeling, the soil is often replaced by a more straightforward system called a subgrade model. The Winkler method of linear elastic springs is a popular method of soil modeling in which the spring constant shows the modulus of subgrade reaction. In this research, the factors affecting the distribution of the modulus of subgrade reaction of elastoplastic subgrades are examined. For this purpose, critical theories about the modulus of subgrade reaction were examined. A square raft foundation on a sandy soil subgrade with was analyzed at different internal friction angles and Young's modulus values using ABAQUS software. To accurately model the actual soil behavior, the elastic, perfectly plastic constitutive model was applied to investigate a foundation on discrete springs. In order to increase the accuracy of soil modeling, equations have been proposed for the distribution of the subgrade reaction modulus. The constitutive model of the springs is elastic, perfectly plastic. It was observed that the modulus of subgrade reaction under an elastic load decreased when moving from the corner to the center of the foundation. For the ultimate load, the modulus of subgrade reaction increased as it moved from the corner to the center of the foundation.

• 한국농공학회지
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• 제45권2호
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

• Geomechanics and Engineering
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• 제38권2호
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• pp.157-164
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• 2024

This paper describes the general trends of the stress-strain behavior of Korean weathered soil prior to failure and behavior at failure under triaxial loading. The isotropically consolidated samples were tested in a testing device under monotonic undrained loading. Relative density, effective mean pressure and fine content were the factors varied in the experimental investigation. The test results were analyzed and their behaviors were interpreted within the framework of plasticity constitutive model for a weathered Korean silty sand. Possible physical bases for the proposed forms are discussed. Validation of the applied model using the laboratory results is also given.

• 대한토목학회논문집
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• 제13권3호
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• pp.163-172
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• 1993

본 문은 Lade의 Single surface 구성모델의 변형율 예측 능력을 평가하기 위해 백마강모래를 사용, 등방압축시험과 배수삼축시험을 반복 시행하여 모델에 필요한 각 토질매개변수값을 다수 구하여 통계처리 하였다. 그리고 1계근사법을 이용하여 이 구성모델의 변형율 예측능력을 확률론적으로 평가하였다. 그 결과 변동계수와 상관계수를 효과적으로 이용하여 토질매개변수의 수를 줄일 수 있을 것으로 기대되며 변동계수가 0.51 이하로서 이 구성모델의 변형율 예측 능력은 확률론적으로 매우 안정된 구성모델임을 알았다.

• 한국농공학회지
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• 제35권4호
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• pp.106-118
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• 1993

The purpose of this study is to develop a multireservoir water balance model which may be used to evaluate rural water demands such as agricultural water, domestic water, industrial water and livestock water and to determine effective storage of reservoir. The model was verified to compare the observed reservoir release data with the simulated reservoir release data of the existing Munsan and Dongbu reservoirs located in the Gisan rural district for 3 years('87~'89). For model application, the effective storages of existing reservoirs(Munsan & Dongbu) were evaluated for 10-year frequency drought and that of newly planned reservoirs(Kumbok & Kudong) were determined for 10-year frequency drought. In addition, the behavior of effective storages for existing reservoirs were analyzed in the case of introducing new reservoirs in the existing system.

• 한국지반공학회지:지반
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• 제11권3호
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• pp.43-54
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• 1995

실트질 모래를 재료로 삼축압축시험기를 개조하고, 삼축셀에 고압공기투과판을 부착하여 축변환기법에 의해 흡인력과 순평균응력을 조절하면서 등력압축시험과 전단시험을 행하여, 불포화 상태에 따른 토질정수의 변화를 규명하였으며, 함수상태의 변화에 따라 응력, 체적변화 등의 거동특성을 검토하였다. 실험의 결과에서 규명된 불포화토의 특성을 바탕으로, 불포화토의 응력성분을 고려하고, 수정 Cam -Clay 모델을 경계조건으로 하는 불포화토의 거동예측을 위한 구성식을 개발하고, 실트질 모래에 대한 실내실험의 자료로부터 구한 관측치와 예측치를 비교하여 이의 타당성을 검증하였다.

• Geomechanics and Engineering
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• 제16권3호
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• pp.309-320
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• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.