• Title, Summary, Keyword: Stress path

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

  • 정진섭;권원식
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.40 no.1
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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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Stress-Strain-Strain Rate of Overconsolidated Clay Dependent on Stress and Time History (응력이력과 시간이력에 따른 과압밀점토의 응력-변형-변형률 속도)

  • 한상재;김수삼;김병일
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.143-150
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    • 2003
  • This study deals with the stress-strain-strain rate behaviour of overconsolidated clay. Consolidated-drained stress path tests were performed on the stress-time dependent condition. Stress history consists of rotation angle of stress path, overconsolidation ratio, and magnitude of length of recent stress path. Time history includes loading rate of recent and current stress path. Test results show that all influence factors have an increasing strain rate with time, and the strain rate varies with the change of the rotation angle of stress path. With the increase of overconsolidation ratio and loading rate of current stress path, the strain rate also increases. For the stress history, correlation between stress-strain and strain rate is indicated but the time history is not.

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

  • 김병일;신현영;이승원;김수삼
    • Proceedings of the Korean Geotechical Society Conference
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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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The Effects of Stress History on the Behaviour of Overconsolidated Clay (과압밀점토의 응력이력 의존성에 관한 연구)

  • 김병일;신현영;김용수;김수삼
    • Proceedings of the Korean Geotechical Society Conference
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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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Parameters Characteristics of Single Work Hardening Model Dependent on the Stress Path (응력경로에 따른 단일항복면구성모델의 토질매개변수 특성)

  • 김찬기
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.38 no.2
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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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Development of a Stress Path Search Model of Evolutionary Structural Optimization Using TIN (점진적 최적화 기법에서 불규칙 삼각망을 이용한 평면구조의 응력경로 탐색모델의 개발)

  • Kim, Nam-Su;Lee, Jeong-Jae;Yoon, Seong-Soo;Kim, Yoon-Soon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.4
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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.

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

  • 정진섭;김찬기;박을축
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.38 no.3
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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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The Effects of Stress and Time History on Pore Pressure Parameter of Overconsoldated clay (과압밀점토의 간극수압계수에 응력이력과 시간이력이 미치는 영향)

  • 김수삼;김병일;한상재;신현영
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.4
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    • pp.286-294
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    • 2002
  • This study investigated the effects of stress and time history of overconsolidated clayey soils on pore pressure parameter, A. Laboratory tests were carried out under the conditions of both varying stress and time history. The stress history is classified into (i) rotation angle of stress path, (ii) overconsolidation ratio, and (iii) magnitude of length of recent stress path. The time history is divided into (i) loading rate of recent stress path and (ii) rest time. Pore pressure parameters are different both in the magnitude and trend with the rotation angle, depending on the magnitude of overconsolidation ratio but not in a trend. In addition, the pore pressure parameters have no effects on the magnitude of length of recent stress path except the level of initially small strain, while loading rates of recent stress path have effects on it. Finally, the pore pressure parameters of overconsolidated clays increase with the existence of the rest time, until either the deviator stress exceeds 70 kPa or the strain up to 0.1%.

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

  • Lee, Hyung-Jin;Choi, Won;Lee, Jeong-Jae
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.6
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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.

Evaluation of Single Hardening Constitutive Model for Sand (모래에 대한 단일항복면 구성모델의 평가)

  • Jeong, Jin-Seob;Park Moung-Bae
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.40 no.6
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    • pp.95-103
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    • 1998
  • Solutions of geotechnical engineering problems require calculation of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such calculation even for complicated problems. To get accurate results, realistic stress-strain relationships of soil 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. The nature of stress-path dependency, the principle that governs deformations in sand, and the use of Lade's single work-hardening model for predicting sand 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 sand exhibits stress-path dependent behavior. The strains calculated from Lade's single work-hardening model are in reasonable agreement with those measured, but some discrepancies occur. The largest difference between measured and calculated strains occurs for proportional loading with increasing stresses and for stress-path directions.

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