• Title/Summary/Keyword: geotechnical behavior

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Characteristics of Deformation and Shear Strength of Parallel Grading Coarse-grained Materials Using Large Triaxial Test Equipment (대형삼축시험에 의한 상사입도 조립재료의 변형 및 전단강도 특성)

  • Jin, Guang-Ri;Snin, Dong-Hoon;Im, Eun-Sang;Kim, Ki-Young
    • Journal of the Korean Geotechnical Society
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    • v.25 no.12
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    • pp.57-67
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    • 2009
  • Along with the advanced construction technologies, the maximum size of coarse aggregate used for dam construction ranges from several cm to 1m. Testing the original gradation samples is not only expensive but also causes many technical difficulties. Generally, indoor tests are performed on the samples with the parallel grading method after which the results are applied to the design and interpretation of the actual geotechnical structure. In order to anticipate the exact behavior characteristics for the geotechnical structure, it is necessary to understand the changes in the shear behavior. In this study, the Large Triaxial Test was performed on the parallel grading method samples that were restructured with river bed sand-gravel, with a different maximum size, which is the material that was used to construct Dam B in Korea. And the Stress - Strain characteristics of the parallel grading method samples and the characteristics of the shear strength were compared and analyzed. In the test results, the coarse-grained showed strain softening and expansion behavior of the volume, which became more obvious as the maximum size increased. The internal angle of friction and the shear strength appeared to increase as the maximum size of the parallel grading method sample increased.

Numerical Investigation on Combined Load Carrying Capacity and Consolidation Behavior of Suction Piles (석션파일의 조합하중 지지력 및 압밀거동에 관한 수치해석 연구)

  • Yoo, Chung-Sik;Hong, Seung-Rok
    • Journal of the Korean Geotechnical Society
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    • v.30 no.1
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    • pp.103-116
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    • 2014
  • This paper presents the results of a numerical investigation on the load carrying capacity and consolidation behavior of suction piles. Three dimensional numerical models which reflect realistic ground conditions and installation procedures including the ground-suction pile interface were adopted to conduct a parametric study on variables such as the length-diameter ratio and the loading configurations, i.e, vertical, horizontal, and combined loads. The results indicated that the load carrying capacity of a suction pile can only be realistically obtained when the interface behavior between the suction pile and the ground is correctly modeled. Also carried out was the stress-pore pressure coupled analysis to investigate the consolidation behavior of the suction pile after the application of a vertical loading. Based on the results, failure envelops and associated equations were developed, which can be used to estimate load carrying capacity of suction piles installed in similar conditions considered in this study. The results of consolidation analysis based on the stress-pore pressure coupled analysis indicate that no significant excess pore pressure and associated consolidation settlement occur for the loading configuration considered in part due to the load transfer mechanism of the suction pile.

A Constitutive Model on the Behavior Under $K_0$ Condition for Cohesionless Soils and Optimization Method of Parameter Evaluation Based on Genetic Algorithm (사질토의 $K_0$ 조건하 거동에 대한 구성모델 및 유전자 알고리즘을 적용한 계수의 최적화 산정기법)

  • 오세붕;박현일
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.37-48
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    • 2004
  • This study is focused on the constitutive model in order to represent brittleness and dilatancy for cohesionless soils. The constitutive model was based on an anisotropic hardening rule derived from generalized isotropic hardening nile, which includes an appropriate hardening equation for the overall strain behavior at small to large strains. The yield surface is a simple cylinder type in stress space and it makes the model practically useful. Hence dilatancy behavior in cohesionless soils could be modeled reasonably. A peak stress ratio was defined in order to model brittle stress-strain relationships. An optimized design methodology was proposed on the basis of real-coded genetic algorithm in order to determine parameters for the proposed model systematically. The material parameters were then determined by that algorithm. In order to verify the proposed model, triaxial tests were performed under $K_0$ conditions far weathered soils. In comparison with the triaxial test results under $K_0$ conditions, the proposed model could calculate appropriately the actual effective stress behavior on brittle stress-strain relationships and dilatancy.

A Numerical Analysis of Load Transfer Behavior of Axially Loaded Piles (축하중 재하말뚝의 하중전이 거동에 대한 수치해석)

  • 오세붕;최용규
    • Geotechnical Engineering
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    • v.14 no.2
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    • pp.93-106
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    • 1998
  • The behavior of axially loaded pile was analyzed by two methodologies: one is the finite difference method using load transfer curves recommended by API(1993) , and the other is the numerical analysis using the FLAC program. From both analyses, load-displacement curves and load distributions along the depth were evaluated appropriately for the measured. The analysis using the FLAC could capture the nonlinearity of load-displacement curve even for unloading and reloading cases, since the unloaded stress paths of fill layer elements occurred on the failure envelop. Futhermore, the measured load transfer curves were compared with the API recommendations and with the calculations obtained front the results of the FLAC analysis for the interpretation of the transfer behavior between the soil and the pile under axial loadings. It was concluded that the atrial behavior of open ended piles at Pusan could be evaluated by both the finite difference analysis using API load transfer curves and the numerical analysis using FLAC.

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