Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
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Evaluation on Applicability of Finite Element Analysis in Model Test of Pile Pullout

말뚝 인발모형실험에 대한 유한요소해석의 적용성 평가

  • You, Seung-Kyong (Dept. of Civil Engineering, Myongji College) ;
  • Shin, Heesoo (Institute of Technology Research and Development, UCI Tech co. Ltd.) ;
  • Lee, Kwang-Wu (Infra safety Institute, Korea Institute of Civil engineering and building Technology) ;
  • Park, Jeong-Jun (Incheon Disaster Prevention Research Center, Incheon National University) ;
  • Choi, Choong-Lak (Geotechnical Engineering Depatment, Pyunghwa Engineering Consultants) ;
  • Hong, Gigwon (Institute of Technology Research and Development, Korea Engineering & Construction)
  • Received : 2019.05.21
  • Accepted : 2019.06.17
  • Published : 2019.06.30
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Abstract

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.

본 연구에서는 말뚝의 인발저항에 대한 합리적 평가를 위하여, 다양한 지반 조건(상대밀도, 세립분 함유율)에서 말뚝의 인발거동 모사에 대한 유한요소해석의 적용성을 평가하였다. 즉, 기존의 실내모형실험 결과(You et al., 2018)를 대상으로 동일한 조건에서의 유한요소해석을 실시하였고, 유한요소해석에 이용된 해석모델의 신뢰성을 검증하였다. 또한 수치해석을 활용한 말뚝의 인발거동 모사에 대한 적정성을 평가하였다. 그 결과, 가상지반이 적용된 축대칭 해석을 이용하여 말뚝의 주면마찰력을 평가할 수 있는 것으로 확인되었다. 또한 다양한 지반 조건에 대하여 말뚝-지반 경계면의 전단저항 특성을 반영할 수 있는 축대칭 해석은 말뚝의 합리적인 인발거동 모사가 가능한 해석방법으로 활용이 가능한 것으로 분석되었다. 따라서 본 연구를 통하여 제안된 해석모델은 말뚝의 응력-변형 관계를 통한 인발거동을 적절하게 모사할 수 있는 것으로 판단되었다.

Keywords

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Fig. 1. Pullout test results by fines content and relative density of soil

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Fig. 2. FEA analysis model

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Fig. 3. Verification procedure of FEA analysis model

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Fig. 4. Distribution of plane strain and axisymmetric analysis result (pullout force by load step=33N)

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Fig. 5. Comparison of analysis and measurement at Dr = 40%

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Fig. 6. Comparison of analysis and measurement at Dr = 60%

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Fig. 7. Comparison of analysis and measurement at Dr = 80%

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Fig. 7. Comparison of analysis and measurement at Dr = 80% (Continued)

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Fig. 8. Distribution on axial stress and pullout resistance of pile according to relative density

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Fig. 8. Distribution on axial stress and pullout resistance of pile according to relative density (Continued)

Table 1. Pullout test cases of model pile by fines content and relative density of soil (You et al., 2018)

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Table 2. Parameters in applied FEA

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Table 3. Comparison of plane strain and axisymmetric analysis result

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Table 4. Analysis result by FEA

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