• Title/Summary/Keyword: 압입시험

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Bearing Behavior Characteristics of Pressure Penetrating Steel Pipe Pile Under Compression Load (압축하중을 받는 압입강관말뚝의 지지거동 특성)

  • Kwon, Ohkyun
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.7
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    • pp.5-13
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    • 2015
  • The pressure penetrating steel pipe pile method which can be constructed in a narrow space using the hydraulic jack is used on the foundation reinforcement, extension of the structure and basement, restoration of the differential settlement etc.. This method is possible to construct in narrow areas and low story height, the non-noise and non-vibration works, and it is possible for the construction site to be clean without slime. And it is possible to confirm the bearing capacity of pile due to penetrating the pile with the compression load of hydraulic jack. In this study, the static load test with the load-transfer test was carried out to investigate the bearing behavior characteristics of the pressure penetrating steel pipe pile. Four series of static load test were executed to investigate the variation of bearing behavior of the pressure penetrating steel pipe pile. As a result of these tests, the allowable load of the pressure penetrating steel pipe was evaluated more than 637 kN, and the shaft resistance corresponding to 81~86% of each applied load was mobilized with only a small portion of the base resistance acting. And it was also evaluated that the unit skin friction was mobilized to maximum value after two months.

A Study on Utilizing Instrumented Indentation Technique for Evaluating In-field Integrity of Nuclear Structures (원전 구조물의 가동 중 건전성 평가를 위한 연속압입시험법의 활용에 관한 연구)

  • Song, Won-Seok;Kim, Seung-Gyu;Ahn, Hee-Jun;Kim, Kwang-Ho;Kwon, Dongil
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.2
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    • pp.165-172
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    • 2013
  • Power generating unit structures are designed and built to meet standard to secure its safety for expected life time. As the structures have been exposed to combined environment, degradation of structure material is accelerated and it can cause unexpected damage; evaluating precise mechanical properties of weak site like welded area is an essential research area as it is directly connected to safety issues. Existing measuring technique like tensile test requires specific size in testing specimen yet it is destructive method which is hard to apply on running structures. To overcome above mentioned limitation, IIT is getting limelight as it is non-destructive and simple method. In this study, latest technique is introduced to evaluate tensile property and residual stress by analyzing stress field occurs under the indenter while IIT is performed. Test on welded area, the weak site of nuclear structures have been practiced and confirmed that IIT can be usefully applied to evaluate integrity in industry.

A Conical Indentation Technique Based on FEA Solutions for Property Evaluation (유한요소해에 기초한 원뿔형 압입 물성평가법)

  • Hyun, Hong-Chul;Kim, Min-Soo;Lee, Jin-Haeng;Lee, Hyung-Yil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.9
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    • pp.859-869
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    • 2009
  • The sharp indenters such as Berkovich and conical indenters have a geometrical self-similarity in theory, but different materials have the same load-depth curve in case of single indentation. In this study, we analyze the load-depth curves of conical indenter with angles of indenter via finite element method. From FE analyses of dual-conical indentation test, we investigate the relationships between indentation parameters and load-deflection curves. With numerical regressions of obtained data, we finally propose indentation formulae for material properties evaluation. The proposed approach provides stress-strain curve and the values of elastic modulus, yield strength and strain-hardening exponent with an average error of less than 2%. It is also discussed that the method is valid for any elastically deforming indenters made of tungsten carbide and diamond for instance. The proposed indentation approach provides a substantial enhancement in accuracy compared with the prior methods.

Microstructure and annealing effect on fracture behavior in the dental glass-infiltrated alumina (치아용 유리침윤 알루미나에서 파괴거동에 미치는 미세구조 및 어닐링 효과)

  • 정종원;최성철
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.4
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    • pp.330-336
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    • 2000
  • Effects of microstructure and indentation stress on fracture behavior of glass-infiltrated alumina composite for dental restorative application were investigated by the Hertzian and Vickers indentation method. Indentation stress-strain curve of glass-infiltrated alumina has showed the quasi-plastic behavior - deviation from linearity at high stress and the classical Hertzian cone crack, which could be confirmed the subsurface damage micrographs using bonded-interface specimen technique. The indentation stress-strain curves for the starting preforms are strongly dependent on porosity and microstructure of the preforms. On the other hand, the curves for the infiltrated composites are relatively insensitive to these factors. The failure of composite is originated at quasi-plastic deformation region. Damage and fracture behavior due to Hertzian stress field is theoretically examined, so that the indentation stress field plays a great role in material degradation. After Hertzian indentation annealing processing changes fracture behavior of alumina composite, so that stress field in material is healed through annealing.

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A Dual Triangular Pyramidal Indentation Technique Based on FEA Solutions for Material Property Evaluation (유한요소해에 기초한 이중 삼각뿔 압입 물성평가법)

  • Kim, Min-Soo;Hyun, Hong-Chul;Lee, Jin-Haeng;Lee, Hyung-Yil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.1
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    • pp.17-28
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    • 2012
  • In this study, we suggest a method for material property evaluation by dual-triangular pyramidal indenters using the reverse analysis. First, we demonstrated that load-displacement curves of conical and triangular pyramidal indenters are different for the same material. For this reason, an independent research on the triangular pyramidal indenter is needed. From FE indentation analyses on various materials, we then investigated the relationships among material properties, indentation parameters and load-displacement curves. From this, we established property evaluation formula using dual-triangular pyramidal indenters having two different half-included-angles. The approach provides the values of elastic modulus, yield strength and strain-hardening exponent within an average error of 3% for various materials.

Application of Rotary Cutting Test for Performance Assessment of Tunnel Boring Extender (TBE의 굴착성능 평가를 위한 회전식 절삭시험의 적용)

  • Jeong, Hoyoung;Jeon, Seokwon;Cho, Jung-Woo
    • Tunnel and Underground Space
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    • v.32 no.4
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    • pp.243-253
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    • 2022
  • In this study, the cutting efficiency of TBE (Tunnel Boring Extender) was evaluated by using rotary cutting tester. In the rotary cutting test, a specimen which has a drilled hollow hole at the center was made of rock-like material. The specimen was cut by UDC (undercutting disc cutter) with spiral cutting path to simulate the cutting process of TBE. The cutting forces and specific energy were evaluated under different cutting conditions. The results indicated that the cutter forces of UDC linearly increased with the vertical and radial penetration depths. Among the three directional cutter forces, the normal force is larger than other force components. While the specific energy decreased with the two penetration depths, in particular, it was presumed that the specific energy was minimized at a certain value of the ratio of radial to vertical penetration depth.

Investigation of Axially Loaded Jacked Pile Behavior by Pile Load Test (말뚝재하시험을 통한 압입강관말뚝의 연직지지거동 분석)

  • Baek, Sung-Ha;Do, Eun-Su;Kim, Seok-Jung
    • Journal of the Korean Geotechnical Society
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    • v.34 no.7
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    • pp.39-49
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    • 2018
  • Jacked pile that involves the use of hydraulic jacks to press the piles into the ground is free from noise and vibration, and is possibly installed within a limited construction area. Thus, as an alternative to conventional pile driving methods, pile jacking could become widely accepted for the construction projects in urban area (e.g., reconstruction or remodeling construction projects). Great concern has arisen over the prediction of axially loaded jacked pile behavior. Against this background, a series of pile load tests were hence conducted on a jacked steel pipe pile installed in weathered zone (i.e., weathered soil and weathered rock). From the test results, base resistance and shaft resistance for each test condition were evaluated and compared with the values predicted by the previous driven pile resistance assessment method. Test results showed that the previous driven pile resistance assessment method highly underestimated both the base and shaft resistances of a jacked pile; differences were more obviously observed with the shaft resistance. The reason for this discrepancy is that a driven pile normally experiences a larger number of loading/unloading cycles during installation, and therefore shows significantly degraded stiffness of surrounding soil. Based on the results of the pile load tests, particular attention was given to the modification of the previous driven pile resistance assessment method for investigating the axially loaded jacked pile behavior.