• Title, Summary, Keyword: 인발 거동

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Numerical Analysis of Uplift Behavior of Anchor Expanded by Pulse Discharge Technology (펄스 방전에 의해 확공된 앵커의 인발 거동에 대한 수치 해석)

  • Park, Hyun-Ku;Lee, Seung-Rae;Kim, Tae-Hoon
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1095-1102
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    • 2010
  • 본 연구에서는 펄스 방전 기술에 의해 확공된 앵커의 인발 거동에 대한 수치해석을 수행하였다. 펄스 방전 현상을 등가의 폭발 현상으로 모델링하여 점성토와 사질토 지반에 대한 확공해석을 수행하였으며 이를 통해 펄스 방전에 의해 개량된 지반 조건을 구현하였다. 확공된 지반에 대해 설치된 압축형 그라우트 앵커의 인발 거동을 시뮬레이션하여 인발력-인발변위 곡선을 산정하였다. 해석 결과, 점성토의 경우에는 확공 정도가 인발 거동과 밀접한 관련을 갖는 반면, 사질토의 경우에는 확공 정도 이외의 추가적인 증가 요인이 확인되는 것으로 나타났으며 펄스 방전 기술이 사질토 지반의 다짐을 통해 앵커의 인발력을 증가시키는 것으로 판단되었다.

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A Study on the Pullout Behavior of Shear Connectors which Fix the Additional Wall to the PHC-W Piles in the PHC-W Type Permanent Building Retaining Wall (PHC-W 흙막이를 활용한 건축영구벽체에서 PHC-W말뚝과 증설벽체를 합벽시키는 전단연결재의 인발거동에 관한 연구)

  • Jin, Hong-min;Kim, Sung-su;Choi, jeong-pyo;Choi, Yongkyu
    • Journal of the Korean Geotechnical Society
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    • v.33 no.12
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    • pp.107-113
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    • 2017
  • Shear Connector should be used to fix the PHC pile with extension wall in order to utilize PHC-W retaining wall as permanent wall. The pullout behaviours on shear connectors anchored into PHC-W pile were observed as two modes. The first type behaviour showed that after reaching the maximum pullout resistance, the anchorage was broken and shear connector was pulled out abruptly. The second type behaviour showed that even after arriving the maximum pullout resistance, the anchorage was not destroyed and there was a progressive increase in pullout displacement. The maximum pullout resistance of the steel anchor shear connector is larger than that of deformed bar shear connector. The larger the diameter and the longer the embedment length of shear connector, the higher the maximum pullout resistance would be. The pullout displacements corresponding to the maximum pullout resistance of the shear connector showed various ranges regardless of the materials, the diameters and the anchoring lengths. A-D20 shear connectors showed a pull-out displacement of about 8~10 mm. A-D16, D-D19 and D-D16 shear connectors exhibited a pulling displacement of about 14~20 mm, but a pulling displacement of about 6~10 mm when the anchoring lengths were 50 and 80 mm.

Field Pull-out Test and 3-D FEM Analysis for Steel Pipe Nailing Installed Foldable Wedge (접이식 웨지 장착 강관네일의 현장 인발시험 및 3차원 유한요소해석)

  • Kwon, Kyo-Keun;Choi, Bong-Hyuck
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.6C
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    • pp.313-319
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    • 2009
  • In this study, field pull-out test and 3-D FEM analysis have been performed for examining and reflecting the behavior of steel pipe nailing installed foldable wedge. Field pull-out test was performed under various conditions. As a result, the steel pipe nailing installed foldable wedge has an effect of pull-out resistance increased about 30% in comparison with non-wedge type steel pipe nailing. Through back analysis in 3-D FEM for behavior of non-wedge type steel pipe nailing, friction characteristics between nail to soil was analyzed and obtained first consistent with field pull-out behavior. Then, the frictional characteristic was used for analyzing the behavior of the steel pipe nailing installed foldable wedge. The result was compared with the test results. Consequently, friction coefficient (${\mu}$) of about 1.2 between grout to soil leads to good agreement with analysis results and test results. And a limited pull-out resistance, $$T_L{\sim_=}32$$ tonf is similar to field pull-out test result which is improved about 33% in comparison with non-wedge type steel pipe nailing's $$T_L{\sim_=}24$$ tonf.

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Estimation of Pull-out Behavior for Steel Pile Nailing installed Foldable Wedge by Field Measurement (현장계측에 의한 접이식 웨지 장착 강관네일의 인발거동 평가)

  • Kwon, Kyo-Keun;Choi, Bong-Hyuck;Kim, Kyung-Min
    • Journal of the Korean Geosynthetics Society
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    • v.8 no.4
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    • pp.19-25
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    • 2009
  • In this study, field pull-out tests were performed for steel pipe nailing installed foldable wedge and non-wedge type steel pipe nailing under the same test conditions. This is to evaluate pull-out resistance improvement effect of steel pipe nailing installed foldable wedge. Evaluating for field pull-out characteristics of steel pipe nailing installed foldable wedge was performed through analysis of ultimate pull-out resistance ($T_L$), ultimate unit skin friction ($q_s$, $u_{max}$), tensile normal stiffness ($K_{\beta}$), tension of nail. As a result, the steel pipe nailing installed foldable wedge have an effect of pull-out resistance increased about 30% in comparison with non-wedge type steel pipe nailing.

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Study on Pullout Behavior and Determination of Ultimate Uplift Capacity of Pile Driven in Small Pressured Chamber (소형 압력 토조내에 타입된 말뚝의 인발 거동과 극한 인발 지지력 결정에 관한 연구)

  • 최용규
    • Geotechnical Engineering
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    • v.11 no.2
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    • pp.19-28
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    • 1995
  • Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.

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Influence of Number of Twist on Tensile Behavior of High Performance Fiber Reinforced Cementitious Composites with Twisted Steel Fibers (비틀림 강섬유의 비틀림 횟수가 고성능 섬유보강 시멘트 복합재료의 인장거동에 미치는 영향)

  • Kim, Dong-Joo
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.575-583
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    • 2010
  • This research investigated the influence of the number of twist on single fiber pullout behavior of Twisted steel (T-) fiber and tensile behavior of high performance cementitious composites reinforced with the (T-) fibers (HPFRCC). Micromechanical pullout model for T- fibers has been applied to analytically investigate the influence of various fiber parameters including the number of twist on single fiber pullout behavior; and, to optimize the number of twist to generate larger pullout energy during fiber pullout without fiber breakage. In addition, an experimental program including single fiber pullout and tensile tests has been performed to investigate the influence of twist ratio experimentally. Two types of T- fiber with different twisted ratios, T(L)- fiber (6ribs/30 mm) and T(H)- fiber (18ribs/30 mm), were tested. T(L)- fiber produced higher equivalent bond strength (larger pullout energy) although T(H)- fiber produced higher pullout stress during pullout since T(H)- fiber showed fiber breakage during pullout. Tensile test results confirmed that T(L)- fiber in high strength mortar generates better tensile performance of HPFRCC, e.g., load carrying capacity, strain capacity and multiple micro-cracking behavior.

Effect of Polyvinyl Alcohol Fiber Volume Fraction on Pullout Behavior of Structural Synthetic Fiber in Hybrid Fiber Reinforced Cement Composites (하이브리드 섬유 보강 시멘트 복합 재료에서 구조용 합성 섬유의 인발 거동에 미치는 폴리비닐 알코올 섬유 혼입률의 효과)

  • Lee, Jin-Hyung;Park, Chan-Gi
    • Journal of the Korea Concrete Institute
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    • v.23 no.4
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    • pp.461-469
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    • 2011
  • In this study, the effect of polyvinyl alcohol (PVA) fiber volume fraction on the pullout behavior of structural synthetic fiber in hybrid structural synthetic fiber and PVA fiber cement composites are presented. Pullout behavior of the hybrid fiber cement composites and structural synthetic fiber were determined by dog-bone bond tests. Test results found that the addition of PVA fiber can effectively enhance the structural synthetic fiber cement based composites pullout behavior, especially in fiber interface toughness. Pullout test results of the structural synthetic fiber showed the interface toughness between structural synthetic fiber and PVA fiber reinforced cement composites increases with the volume fraction of PVA fiber. The microstructural observation confirms the incorporation of PVA fiber can effectively enhance the interface toughness mechanism of structural synthetic fiber and PVA fiber reinforced cement composites.

Pullout Capacity of Ground Anchors in Weathered Soil (풍화토 지반에 설치된 앵커의 인발 특성)

  • 김낙경
    • Journal of the Korean Geotechnical Society
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    • v.17 no.4
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    • pp.231-239
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    • 2001
  • 건설 현장에서 널리 사용되고 있는 그라운드 앵커의 거동 특성을 연구하기 위하여 계측기를 부착한 일곱 개의 그라운드 앵커를 국내에 널리 분포되어 있는 화강 풍화토 지반인 $\bigcirc$$\bigcirc$$\bigcirc$대학교 지반 시험장에 설치하여 인발 시험을 수행하였다. 저압 그라우트 인장형 앵커 3개와 압축형 앵커 4개를 시험하였고, 시험은 AASHTO 규정에 의거한 인발시험, 크리프시험, 장기거동시험을 수행하였다. 시험 결과로부터 화강 풍화토 지반에 설치된 저압그라우트 직선형 앵커의 지반과의 마찰계수, 크리프 변형율, 하중감소 특성을 평가하였다.

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A study on pull-out behaviours of shotcrete steel fibers according to different shapes (숏크리트 강섬유 형상에 따른 인발 거동에 대한 연구)

  • Kim, Sang-Hwan;Kim, Ji-Tae
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.1
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    • pp.71-82
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    • 2011
  • This paper presents the tensile strength of shotcrete steel fibers depending on the shape of steel fiber. The experimental and numerical analyses are performed in this study. In experimental study, a series of laboratory pullout tests are carried out by changing both the angle and the length of the embedded steel fiber according to the corresponding type of steel fiber in order to derive the optimal type of steel fiber. Results obtained from the experimental work are evaluated and compared with the numerical analysis results. The results clearly show that the pull-out strength of the steel fiber are increased with increasing the hook angle and embedded angle of steel fiber. It is also found that the pull-out strength of the steel fiber is larger in case of the short steel fiber body length.

Evaluation on Applicability of Finite Element Analysis in Model Test of Pile Pullout (말뚝 인발모형실험에 대한 유한요소해석의 적용성 평가)

  • You, Seung-Kyong;Shin, Heesoo;Lee, Kwang-Wu;Park, Jeong-Jun;Choi, Choong-Lak;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.2
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    • pp.11-21
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    • 2019
  • This paper describes the applicability of FEA(Finite Element Analysis) to the simulation of pile pullout behavior under various soil conditions (relative density and fines content), in order to evaluate reasonably the pullout resistance of pile. That is, the results of previous research (You et al., 2018) were analyzed by FEA under the same conditions. The FEA results showed that axisymmetric analysis using virtual ground was able to evaluate the skin friction of the pile. Also, axisymmetric analysis, which can apply the shear resistance characteristics of the pile-soil interface in various soil conditions, could be used as an analytical method that can simulate a reasonable pile pullout behavior. Therefore, the analytical model proposed in this study was able to simulate appropriately the pullout behavior based on the stress-strain relationship of the pile-soil interface.