• Title/Summary/Keyword: Pile deformation

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Numerical Study of Heat Transfer Efficiency, Performace and Mechanical Behavior induced by Thermal Stress of Energy Pile (에너지 파일의 열교환 효율 및 성능, 열응력에 의한 역학적 거동 평가)

  • Min, Sun-Hong;Lee, Chul-Ho;Park, Moon-Seo;Koh, Hyung-Seon;Choi, Hang-Seok
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.6 no.2
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    • pp.9-14
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    • 2010
  • The ground source heat pump system is increasingly being considered as an alternative to traditional heating and cooling systems to reduce the emission of ground house gases. In this paper, A series of numerical analysis for energy piles has been performed focusing on heat transfer efficiency, performance and thermal stress. Results of numerical analyses for the W-shape type shows more efficient heat exchange transfer than the coil type. From results of the thermo-mechanical analysis, it is shown that the concentration of thermal stress occurs around the circulating pipe and the interfaces between different materials. The largest deformation caused by thermal stress is observed in the energy pile.

A Study on Consolidation Characteristics by Considering the Initial Radial Compression at Sand Pile Adjacent Ground (샌드파일 주변지반에서 초기 방사방향 압축에 의한 압밀특성 연구)

  • 천병식;여유현
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.649-656
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    • 2000
  • Consolidation of the ground surrounding the sand piles is delayed by well resistance and smear effect. This study is executed to understand the factors that affect the characteristics of consolidation. This was accomplished by utilizing the estimated and measured values of the soil properties through the monitoring of the ground surrounding the sand piles. When it is assumed that the horizontal coefficient is equal to the vertical coefficient of consolidation, the estimated values is exceedingly similar to the measured values. The properties of the initially disturbed soil by the sand pile installation seemed to improve through the process of consolidation with the passage of time. From the results of the analysis of the settlement measurement, the measured values occurred about 60~90% of the predicted values. Considering the initial radical compression deformation, according to the theory of cavity expansion, the difference between the two appears to be in good agreement. In this study, to understand the behavioral characteristics of the ground surrounding the sand piles requires estimation through considering the initial radial compression as well as smear effect of the soil disturbance and well resistance.

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Derivation of work-hardening exponent using continuous indentation technique (연속압입시험법을 이용한 가공경화지수의 유도)

  • Jeon, Eun-Chae;Ahn, Jeong-Hoon;Kwon, Dong-Il
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.256-261
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    • 2000
  • In this study, we derived work-hardening exponent using continuous indentation test technique. Continuous indentation test technique is a powerful method to evaluate mechanical properties, such as hardness, modulus, ${\sigma}-{\varepsilon}$ curves and etc. It has many merits conventional indentation test has. The relationship between true stress and mean contact pressure and between strain and indentation depth were derived. While the indenter pushes the materials, the region around the indenter is deflected elastically. It is called elastic deflection. And pile-up phenomenon related to plastic deformation around the indenter increased the contact depth, and sink-in phenomenon decreases. So we calibrated contact depth change by considering elastic deflection and pile-up/sink-in. Using calibrated contact depth we redefined the relationship between true stress and mean contact pressure and between strain and contact depth. Through these relationship we could derive work-hardening exponent by analyzing load-depth curves. And it showed good agreement with tensile test results.

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Behavior of Soft Ground Improved by CSCP and SCP Using Centrifuge Modeling (원심모델링을 이용한 CSCP 및 SCP로 개량된 연약지반의 거동)

  • Ahn Kwang-Kuk
    • Journal of the Korean Geotechnical Society
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    • v.22 no.4
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    • pp.21-30
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    • 2006
  • In this study, centrifuge model tests were performed to investigate the stress concentration ratio, bearing capacity and deformation modes of piles in clay ground improved by granular piles with two types of pile (CSCP, SCP) and various replacement ratios (0, 20, 40, 60%). According to the results of tests, the load ratio of ground improved by SCP and CSCP proportionally increased as replacement ratio increased. It shows that average normalized load of ground improved by CSCP is higher by about $8{\sim}21%$ than by SCP. As a result of rigid loading tests, it was evaluated that average stress concentration ratio of CSCP is higher than that of SCP. Only expansion failure occurred in CSCP, whereas SCP showed the expansion and shear failure simultaneously.

Finite Element Anlaysis of Nanoindentation Process and its Experimental Verification (나노 인덴테이션 공정의 유한요소해석 및 실험적 검증)

  • 이정우;윤성원;강충길
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.116-119
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    • 2003
  • In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation was studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass) were used as specimens, and forming conditions to reduce the elastic restoration and pile-up was proposed. The indenter was modeled a rigid surface. Minimum mesh sizes of specimens are 1-10nm Comparison between the experimental data and numerical result demonstrated that the finite element approach is capable of reproducing the loading-unloading behavior of a nanoindentation test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.

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The Measurement Method of Lateral Displacement in Bridge Abutment. (교량구조물의 측방이동 측정방법에 관한 연구)

  • 장용채
    • Journal of Korean Port Research
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    • v.14 no.1
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    • pp.115-124
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    • 2000
  • This study is a suggest a measurement method of lateral displacement, which can be used to judge the stability of bridge abutment on soil undergoing lateral movement. The abutment of bridge on soft foundation makes lateral movement due to the settlement of back fill and lateral flow. To measure the displacement of such a abutment, there are a lot of indirect method for measurement such as survey of leveling or inclinometer gauge around the abutment. But all of them are not sufficient to confirm the ground behavior and measure the exact lateral behavior of structure. As making the structure and pile cooperatively by measuring the movement of lateral displacement, for measuring the abutment displacement precisely by using the inclinometer. In this work, we try to suggest efficient measuring method of abutment displacement and its application.

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Behavior and Lateral Force of H-piles under lateral Soil Movement in Sand (측방변형을 일으키는 모래지반속의 H형 말뚝에 작용하는 수평력)

  • 김영인
    • Journal of Ocean Engineering and Technology
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    • v.16 no.6
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    • pp.44-48
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    • 2002
  • In lateral ground flow, slope stability, and land slide problems, H-piles have often been used, on a horizontally deforming ground, to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, theoretical equations are derived to estimate the lateral force, assuming that the Mohr-Coulomb's plastic states occur in the ground, just around H-piles. In this study, some model experiments were performed to check the lateral forces determined from theoretical equations, using several pile widths, heights and various interval ratios between H-piles for sand specimens. The solution of the theoretical equation, derived from previous studies, showed reasonable characteristics for constants of soil, as well as for the interval, widths, and heights of H-Pile.

A Study on Elastic-Plastic Deformation and 3-D FEA for the Berkovich Nano-Indentation (베르코비치 나노인덴테이션에 대한 3차원 유한요소해석과 탄소성 변형에 관한 연구)

  • Yang Hyeon-Yun;Kim Ji-Soo;Yun Jon-Do;Cho Sang-Bong
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.10 s.175
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    • pp.167-173
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    • 2005
  • The Berkovich nano-indentation is an indentation test method analyzing mechanical properties of materials such as hardness and elastic modulus. The length scale of the penetration is measured in nanometers. Therefore, this method becomes widely useful for analyzing the mechanical property of thin film which can not be measured before. In this paper, comparing two results of the load-displacement curve obtained by the Berkovich nano-indentation and the 3-D finite element analysis, it was confirmed that the 3-D finite element analysis is useful. The phenomenon of pile-up and sink-in due to material properties was discussed by the finite element analysis.

Finite Element Analysis of Nanoindentation Process and its Experimental Verification (나노 인덴테이션 공정의 유한요소해석 및 실험적 검증)

  • 이정우;윤성원;강충길
    • Transactions of Materials Processing
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    • v.12 no.4
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    • pp.382-387
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    • 2003
  • In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behaviors of the materials during indentation were studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled a rigid surface. Minimum mesh sizes of specimens are 1-10nm. Comparisons between the experimental data and numerical result demonstrated that the finite element approach is capable of reproducing the loading-unloading behavior of a nanoindentation test.

Design and analysis of offshore wind structure

  • Young-Suk You;Min-Young Sun;Young-Ho Lee
    • Advances in Computational Design
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    • v.8 no.3
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    • pp.191-217
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    • 2023
  • The objective of this study was to evaluate the foundation structure of a 3.6-MW wind turbine generator (WTG) installed offshore in Western Korea. The ultimate limit state (ULS) and fatigue limit state (FLS) of the multi-pile steel foundation (MSF) installed at the Saemangeum offshore wind farm were structurally investigated using the finite element (FE) software, ANSYS Workbench 19.0. According to the ULS analysis, no plastic deformation was found in any of the components constituting the substructure. At the same time, the maximal stress value reached the calculation limit of 335 MPa. According to the FLS results, the stress concentration factor (SCF) ranged from 1.00 to 1.88 in all components. The results of this study can be applied to determine the optimal design for MSFs.