• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.131-142
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• 1999

The objective of this study is to perform finite element analyses using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening constitutive model had been developed in a companion paper, and was then formulated by implicit stress integration and consistent tangent moduli. A nonlinear finite element analysis program was coded including the algorithm, and as a result, the nonlinear solution was accurately calculated and converged to be asymptotically quadratic. In the analysis of a test embankment it was found that the proposed model could predict the displacement of soils more reasonably than the analysis with von Mises type model. In addition the proposed model could predict accurately the actual behavior through the reanalysis of the problem by a reasonable evaluation of the strength parameter.

• Geotechnical Engineering
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• v.10 no.3
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• pp.17-32
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• 1994

To model the anisotropic behavior of soils in the case of reverse loading, an anisotropic hardening description is proposed on the basis of generalized isotropic hardening(GIH) rule. There is a core of the GIH rule in the allowance of the concept that the center of homology of isotropic hardening can be any proper stress states inside a yield surface. The plastic deformations could be represented for the condition of reverse loading, and an explicit constitutive relationship was formulated by utilizing a simple hardening function. The proposed hardening description has been compared with other anisotropic hardening models. For verification three sets of triaxial test results have been predicted for the drained and undrained behavior of overconsolidated clays and Ko consolidated clays.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.121-130
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• 1999

The objective of this study is to perform finite element analyses(FEA) using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening model was then developed to solve the problem and its mathematical formulations and experimental verifications were also described. In a companion paper, the constitutive equation will be formulated for accurate and efficient solutions of FEA, and coded into a nonlinear analysis program, and finally a field problem will be analyzed. The proposed model includes the failure criterion of a von Mises type and the anisotropic hardening rule based on the generalized isotropic hardening description, which can model the nonlinearity and the anisotropy of the stress-strain relationship. As a result this study could verty the experimental results for UU triaxial tests, CU triaxial tests for overconsolidated samples, and anisotropic loading tests with the rotation of principal stress axes for $K_0$consolidated samples.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.207-214
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• 2002

A constitutive model was implemented in ABAQUS code, The constitutive equation can model the behavior for overall range of strain level from small to large deformation, which is based on anisotropic hardening rule and total stress concept. The formulation includes (1) finite strain formulation on the basis of Jaumann rate, (2) implicit stress integration and (3) consistent tangent moduli. Therefore, the mathematical background was established in order that large deformation analysis can be performed accurately and efficiently with the anisotropic constitutive model. Companion paper(Jeon et al., 2002) will contain the large deformation analysis results of examples with the constitutive model using ABAQUS.

• Geotechnical Engineering
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• v.12 no.6
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• pp.87-100
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• 1996

This paper verifies the accuracy and efficiency of the implicit stress integration algorithm for an anisotropic hardening constitutive model developed in a companion paper[Oh & Lee (1996)3. Simulation of undrained triaxial test results shows the accuracy of the method through an error estimation, and analyses of accuracy and convergence were performed for a numerical excavation problem. As a result, the stress was accurately integrated by the algorithm and the nonlinear solution was converged to be asymptotically quadratic. Furthermore nonlinear FE analysis of a real excavation problem was by performed considering the initial soil conditions and the in-situ construction sequences. The displacements of wall induced by excavation were more accurately estimated by the anisotropic hardening model than by the Cam-clay model.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.65-73
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• 2000

An elasto-plastic constitutive model was proposed, in which the behavior at small-to-large strain level can be modeled. The proposed model is based on the anisotropic hardening description with the generalization of isotropic hardening rule and the total stress concept. From a mathematical approach it was proved that the model includes the previous successful models. The model was verified by a series of resonant column tests, torsional shear tests and triaxial tests, and the proposed model predicted small-to-large strain behavior more consistently and accurately than the hyperbolic model and the Ramberg-Osgood model for a weathered granitic soil. In addition, the nonlinearity under small strain condition was predicted appropriately for the torsional shear test results.

• Geotechnical Engineering
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• v.12 no.4
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• pp.145-156
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• 1996

An implicit stress integration algorithm was formulated for implementing an aiusotorpic hardening constitutive model which has been based op the generalized isotropic hardening rule in nonlinear finite element analysis technique. the rate form of stress tensor was implicitly integrated using the generalized trapezoidal rule and the tangent stress-strain modulus was evaluated consistently with the nonlinear solution technique. As a result, it has been found that the nonlinear analysis with the anisotropic hardening constitutive model might be performed accurately and efficiently.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.75-83
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• 2004

This study is focused on the constitutive model in order to represent brittleness and dilatancy of cohesionless soils. The constitutive model was proposed on the basis of an anisotropic hardening rule with generalized isotropic hardening rule. The shape of yield surface is a simple cylinder type in stress space and it makes the model practically useful. Flow rule was approximated by a concrete function on dilatancy. A peak stress ratio was defined to model brittle stress-strain relationships. The proposed model was formulated and implemented to calculate the stress-strain relationship from triaxial tests. In the companion paper the proposed model will be verified by comparison with the triaxial test results.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.55-62
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• 2002

미소변형에서 대변형에 이르는 전체 변형률 영역의 구성모델을 ABAQUS 코드에 구현하였다. 구성모델은 비등방경화규칙에 근거한 전응력 개념의 탄소성 모델로 연약 점토나 풍화토에 적용하는 것이 가능하다. 사용된 정식화 및 알고리즘은 (1) Jaumann 응력속도를 이용한 대변형도 조건 정식화 (2) 내재적인 응력적분 (3) 일관된 접선계수를 포함하고 있다. 이를 통하여 대변형 해석을 정확하고 효율적으로 수행할 수 있었다. 예제를 통하여 새로운 구성모델과 ABAQUS 코드를 이용한 대변형 해석을 수행할 수 있음을 확인하였다. 특히 전체변형률 영역의 거동을 모델하고 범용 해석 프로그램을 이용한 비선형 대변형 해석에 적용하는 것이 가능하였다.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.61-68
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• 2007

The problem on cyclic plate load tests was analyzed by finite element method using an anisotropic hardening constitutive model. The constitutive model was coded to user subroutine in ABAQUS. Using the result of the analysis, Young's moduli corresponding to various strain levels were evaluated by a back calculation method and were very similar to those of input. On the basis of the back calculation method plate loading tests were verified. As a result, deformation moduli could be evaluated practically from cyclic plate load tests with respect site conditions.