• 제목/요약/키워드: stress-path

검색결과 612건 처리시간 0.02초

과압밀점토의 응력이력 의존성에 관한 연구 (The Effects of Stress History on the Behaviour of Overconsolidated Clay)

  • 김병일;신현영;김용수;김수삼
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2001년도 봄 학술발표회 논문집
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    • pp.161-166
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    • 2001
  • Overconsolidated clays have a different stress history according to the deposit environment. The stress history is classified into (i) rotation angle of stress path, (ii) overconsolidation ratio, and (iii) magnitude of length of recent stress path. Stress-strain behaviour of overconsolidated clays strongly depends on these stress history. In this study a series of drained stress path tests were carried out. Test results indicated that stress-strain behaviour of overconsolidated clay(focused on strain rate) depends on OCR and length of recent stress path, especially rotation angle.

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입상토의 응력경로 의존거동 (Stress-Path Dependent Behavior of Granular Soil)

  • 정진섭;권원식
    • 한국농공학회지
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    • 제40권1호
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    • pp.106-117
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    • 1998
  • The nature of stress-path dependency, the principle that governs deformations in granular soil, and the use of Lade's double work-hardening model for predicting soil response for a variety of stress-paths have been investigated, and are examined The test results and the analyses presented show that under some conditions granular soils exhibit stress-path dependent behavior. For stress-paths involving unloading or reloading, the stress-path with the higher average stress level produces the larger strains, whereas all stress-paths having the same intial states of stress, and involving only primary loading conditions, produce strains of similar magnitudes. Experimental evidence indicates that the stress- path dependent response obtained from the double work-hardening model is also observed for real soils. It is concluded that the influence of stress history on the friction angle is negligible and the strains increment direction is uniquely determined from the state of stress but is not perpendicular to the yield surface. The strains calculated from Lade's double work-hardening model are in reasonable agreement with those measured.

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응력이력과 시간이력에 따른 과압밀점토의 응력-변형-변형률 속도 (Stress-Strain-Strain Rate of Overconsolidated Clay Dependent on Stress and Time History)

  • 한상재;김수삼;김병일
    • 한국지반공학회논문집
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    • 제19권1호
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    • pp.143-150
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    • 2003
  • 과압밀점토의 응력-변형 거동에 중요한 영향을 미치는 변형률 속도에 관하여 다루었다. 본 연구에서는 응력경로 회전각, 과압밀비 그리고 접근길이를 포함한 응력이력과 재하속도 이력 및 재하속도를 포함한 시간이력을 변화시켜 압밀-배수 응력경로 삼축 실험을 수행하였다. 실험 결과 모든 영향인자에 대하여 시간이 증가할수록 변형률 속도 역시 증가하였다. 또한, 회전각의 정의에 따라 상이한 변형률 속도의 값을 보였고, 과압밀비와 재하속도가 증가할수록 변형률 속도 역시 증가하였다. 응력이력에서는 응력-변형 거동과 변형률 속도간의 상관성이 존재하였지만 시간이력에서는 응력-변형-변형률 속도의 상관성을 보이지 않았다.

하중재하속도에 따른 과압밀점토의 응력-변형 거동 (Stress-Strain Behaviour of Overconsolidated Clay with Loading Rate)

  • 김병일;신현영;이승원;김수삼
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2001년도 봄 학술발표회 논문집
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    • pp.239-244
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    • 2001
  • Natural clayey soils or improved grounds are in a overconsolidated conditions due to changes in vertical stress and pore pressures, desiccation, ageing and so on. These grounds show inelastic stress-strain behaviour characteristics within all range of strain except very small strain (${\gamma}$$\_$s/$\leq$10 ̄$^3$∼10 ̄$^4$%) when construction, such as excavations and retaining walls, is performed. Also it strongly depends on loading rate of current stress path and recent stress path. This study carried out drained stress path tests by varying loading rate of current and recent stress path. Test results indicated that stress-strain behaviour of overconsolidated clay depends on loading rate, especially loading rate of current stress path.

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응력경로에 따른 단일항복면구성모델의 토질매개변수 특성 (Parameters Characteristics of Single Work Hardening Model Dependent on the Stress Path)

  • 김찬기
    • 한국농공학회지
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    • 제38권2호
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    • pp.133-144
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    • 1996
  • To get accurate results, the realistic stress-strain relationships of soils are dependent on a number of factors such as soil types, density, stress levels and stress path. Such attempts are continuously being made by the developement of analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate parameters characteristics of Lade's single work hardening model dependant on the stress path. Using the computer program based on the regression analysis, the values of parameters for the model were determined. In conclusion, the parameters of Lade's model are little influenced by the stress paths. Though yield criterion parameters ( h, ${\alpha}$a) are much influenced by stress level and stress path, the parameters don't have influence on stress-strain behavior.

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점진적 최적화 기법에서 불규칙 삼각망을 이용한 평면구조의 응력경로 탐색모델의 개발 (Development of a Stress Path Search Model of Evolutionary Structural Optimization Using TIN)

  • 김남수;이정재;윤성수;김윤순
    • 한국농공학회논문집
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    • 제46권4호
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    • pp.65-71
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    • 2004
  • Stress Path Search Model of Evolutionary Structural Successive Optimization (SPSMESO) using Triangular Irregular Network(TIN) was developed for improving over burden at initial design of ESO and strict stress direction of strut-and-tie model and truss model. TIN was applied for discretizing structures in flexible stress path and segments of TIN was analyzed as one-dimensional line element for calculating stress. Finally, stress path was searched using ESO algorithm. SPSMESO was efficient to express the direction of stress for 2D structure and time saving.

응력경도에 따른 단일항복면구성모델의 응력-변형률 거동 특성 (Stress- Strain Behavior Characteristics of Single Work Hardening Model Dependant on the Stress Path)

  • 정진섭;김찬기;박을축
    • 한국농공학회지
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    • 제38권3호
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    • pp.70-81
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    • 1996
  • Solutions of geotechnical engineering problems require predictions of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such predictions even for complicated problems. To get accurate results, realistic stress-strain relationships of soils are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate stress-strain and volume change characteristics of Lade's single work hardening model dependant on the stress path. In order to predicted of stress-strain and volumetric strain behavior were determined the values of parameters for the mode by the computer program based on the regression analysis. Predicted stress-strain behavior of triaxial compression tests and optional stress path tests for increasing confining pressure with parameters obtained conventional triaxial compression tests agreed with several test results but the prediction results for decreasing confining pressure reduced triaxial compression tests make a little difference with test results.

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점성토지반의 침하거동 평가를 위한 새로운 응력경로시험기법 (A New Stress Path Test Method for Evaluating Settlement Behaviors of Clay Deposits)

  • 정충기;최영태;김창엽;이원택
    • 한국지반공학회논문집
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    • 제19권1호
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    • pp.111-120
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    • 2003
  • 본 연구에서는 점성토지반의 침하량 평가에 보다 적합한 새로운 응력경로시험을 소개하였다. 새로운 시험기법에서는 배압평형과정을 채택함으로써 특정 응력경로상의 모든 점에 대응하는 변형특성을 하나의 시험을 통해 파악할 수 있다. 따라서, 제안된 시험기법을 적용하는 경우, 응력경로법의 실용적인 적용을 위해 필요한 지반의 전반적인 변형거동을 몇 개의 시험만으로 예측할 수 있으며 나아가 기존의 시험기법으로는 수행이 불가능했던 이방적 압밀응력 경로에 대한 변형거동의 평가 역시 실험적으로 가능해진다. 이와 함께 본 연구에서는 성형 카올리나이트 시료에 대해 다양한 응력경로시험을 수행하여 제안된 시험기법의 실험적 적용성을 확인하였으며, 그 결과를 활용하여 전반적인 변형거동과 침하량을 평가하는 실제 과정을 제시하였다.

불규칙 삼각망과 수정된 진화론적 구조 최적화 기법을 이용한 평면구조의 응력 경로 탐색 모델의 개발 (Development of the Stress Path Search Model using Triangulated Irregular Network and Refined Evolutionary Structural Optimization)

  • 이형진;최원;이정재
    • 한국농공학회논문집
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    • 제49권6호
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    • pp.37-46
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    • 2007
  • In designing the structure, the stress path is the basic data. But the stress path is not standardized to analysis the structure. So the one-dimensional frame element structure model with the triangle irregular network is used to solve the problem. And the refined evolutionary structural optimization(RESO) used in structural topology optimization is applied to this study. Through this process, the search method of the stress path is advanced and the burden of the calculation. is reduced.

과압밀점토의 간극수압계수에 응력이력과 시간이력이 미치는 영향 (The Effects of Stress and Time History on Pore Pressure Parameter of Overconsoldated clay)

  • 김수삼;김병일;한상재;신현영
    • 한국해안해양공학회지
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    • 제14권4호
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    • pp.286-294
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    • 2002
  • 본 연구에서는 응력이력과 시간이력이 과압밀 상태에서의 간극수압계수, A(Skempton, 1954)에 미치는 영향에 관하여 실험적으로 규명하였다. 응력경로 회전각, 과압밀비 및 접근길이로 정의되는 응력이력과 재하속도 이력 그리고 정지기간으로 정의되는 시간이력에 따른 간극수압계수(A)의 값과 변화 양상을 보았다. 응력경로 회전각에 따른 간극수압계수(A)는 그 값과 변화 경향에서 상이하게 나타났고, A의 값에 있어서는 과압밀비 의존성을 보였지만, 변화 양상에서는 의존성을 찾아 볼 수 없었다. 접근길이에 따른 간극수압계수(A)는 초기 미소 변형률 구간을 제외하고는 큰 영향을 받지 않았다. 또한, A의 값은 재하속도 이력에 영향을 받았지만, 변화 경향은 모두 동일하게 나타났다. 마지막으로 정지기간에 따른 과압밀점토의 간극수압계수, A는 정지기간의 유무에 따라 변화 경향과 값이 큰 차이를 보이다가 일정 축차응력 또는 변형률을 넘어서면 거의 유사한 값을 나타내었다.