Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Axial Bearing Characteristics of Tip-transformed PHC Piles through Field Tests

현장검증시험에 의한 선단변형 PHC말뚝들의 연직하중 지지특성에 관한 연구

  • Choi, Yongkyu (Dept. of Civil, Environmental and Urban Engrg., Kyungsung Univ.) ;
  • Kim, Myunghak (Dept. of Civil & Urban Engrg., Inje Univ.)
  • 최용규 (경성대학교 공과대학 건설환경도시공학부) ;
  • 김명학 (인제대학교 토목도시공학부)
  • Received : 2018.11.22
  • Accepted : 2018.11.28
  • Published : 2018.11.30
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Abstract

PHC piles, extension-plate attached PHC piles, and steel pipe attached PHC piles were installed in field test site. Axial compressive static load tests including load distribution test and Pile Driving Analyzer (after driving) were done on the tip-transformed PHC piles and the grouted tip-transformed PHC piles. Load-displacement curves of three different type of PHC piles, which are PHC pile (TP-1), extension plate attached PHC pile (TP-2) and steel pipe attached PHC pile (TP-3), showed almost the same behavior. Thus bearing capacity increase effect of the tip-transformed PHC piles was negligible. Share ratio of side resistance and end bearing resistance for PHC pile, extension plate attached PHC pile, and steel pipe attached PHC pile were 95.8% vs. 4.2%, 95.6% vs. 4.4%, and 97.8% vs. 2.2% respectively.

PHC말뚝, 확장판 선단부착 PHC말뚝, 강관 선단부착 PHC말뚝을 현장 시험 부지에서 시험시공하였다. 이들 선단변형 PHC말뚝들에 대하여 하중전이측정이 수반된 연직압축정재하시험을 실시하였으며 시공직후 항타후 동재하시험을 수행하였다. 또한 선단부만 그라우팅한 선단변형PHC말뚝에 대한 연직압축정재하시험도 실시하였다. 3가지 다양한 선단말뚝들 즉, PHC말뚝, 확장판 선단부착 PHC말뚝, 강관 선단부착 PHC말뚝의 하중-침하량 거동은 거의 동일한 양상을 나타내었다. 따라서 말뚝이 선단지지층에 근입된 길이가 동일하고 말뚝 본체의 직경이 동일할 경우 확장판 선단부착 PHC말뚝 및 강관 선단부착 PHC말뚝의 지지력 증대 효과는 거의 없는 것으로 나타났다. 최종재하하중단계에서 PHC말뚝, 확장판 선단부착 PHC말뚝, 강관 선단부착 PHC말뚝의 주면마찰력은 각각 전체 재하하중의 95.8%, 95.6%, 97.8%를 분담하였으며, 선단지지력은 전체 재하하중의 4.2%, 4.4%, 2.2%를 분담하였다.

Keywords

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Fig. 1. Plan of test piles and boreholes

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Fig. 2. Soil profiles

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Fig. 3. N value profile

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Fig. 4. Plan of test and reaction piles

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Fig. 5. Dimensions of test piles

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Fig. 6. Contruction procedure of SDA method (Jo, 2006)

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Fig. 7. Splice of reaction pile and tension steel

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Fig. 8. Load vs. displacement curves of static load test

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Fig. 9. Load vs. displacement curves of tip-transformed PHC piles

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Fig. 10. Axial load distribution of tip-transformed PHC piles

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Fig. 11. Comparision of end bearing resistance

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Fig. 12. Load vs. displacement curves of the grouted end piles

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Fig. 13. Estimation of end bearing resistance using PDA(EOID)

Table 1. Geotechnical profile of the test site

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Table 2. Field test results

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Table 3. Plan of field test for tip-transformed PHC piles

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Table 5. Estimations of ultimate bearing capacity for the tip-transformed PHC piles

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Table 4. Estimation of ultimate bearing capacities by numerical analysis

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