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Research Article

Analysis of Bearing Capacity of Rock Socketed Pre-Bored Super Strength Piles Based on Dynamic Load Test Results

동재하시험을 통한 선단이 암반에 근입된 초고강도 매입 PHC 말뚝의 지지력 특성 분석

Rakhyun Kim1
,
Dongwook Kim2*
김 락현1
,
김 동욱2*
1Nonmember, Manager, Material&Structure Research Group, R&D Center, POSCO E&C tower, 241 Incheon tower-daero, Yeonsu-gu, Incheon 22009, Republic of Korea; formarlly, Graduate Student, Department of Civil and Environmental Engineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
2Member, Associate professor, Department of Civil and Environmental Engineering, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
* Corresponding Author
30 September 2019. pp. 89-100
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Abstract

본 연구에서는 동재하시험을 통해 매입공법으로 선단이 암반에 근입된 초고강도 PHC 말뚝의 지지력 특성을 분석하였다. 초고강도 PHC 말뚝은 일반 고강도 PHC 말뚝에 비해 콘크리트의 강도가 높아 허용구조내력을 향상시킬 수 있었다. 초고강도 PHC 말뚝의 최적 설계를 위해서는 지반지지력도 증가된 구조내력과 균형을 맞출 수 있도록 증가되어야 할 것이다. 오늘날, 지반지지력 검증을 위한 동재하시험 시 경험적으로 고강도 PHC 말뚝과 유사한 항타에너지를 초고강도 PHC 말뚝에 적용하고 있는 실정이다. 동재하시험 결과를 기반으로 초고강도 PHC 말뚝의 지지력에 영향을 미치는 요소들을 분석한 결과, 선단지지력에 대해 선단 주변지반의 표준관입시험 N값의 영향은 미미하였으며, 항타에너지가 증가할수록 선단지지력이 증가하는 경향을 보였다. 그러나 주면마찰력의 경우, 항타에너지의 증가에 따른 변화가 나타나지 않았다. 또한, 허용지지력을 판단하는 Restrike 시험시 선단지지력의 영향은 극히 작아 허용지지력 판단시 합리적인 방안이 필요하다.

The purpose of this study is to analyze the characteristics of bearing capacity of pre-bored super strength PHC (SSPHC) piles socketed in rocks based on dynamic load test results. Because the SSPHC piles have high compressive concrete strengths compared with those of regular high strength PHC piles, the allowable structural strengths of the SSPHC piles were increased. For optimal design of the super strength PHC piles, the geotechnical bearing capacity of the SSPHC piles should also increased to balance the increased allowable structural strength of the SSPHC piles. Current practices of pile installation apply the same amount of driving energy on both SSPHC and high strength PHC piles. As results of analyzing factors that influence bearing strength of SSPHC piles using dynamic load test, there was no relationship between SPT-N value at pile toe and end bearing capacity. But driving energy effects on end bearing capacity. In case of skin friction, driving energy had no effects. And reasonable method verifying design bearing strength is necessary because end bearing capacity is not considered sufficiently in restrike test results.

Keywords
Super strength PHC pile
Pre-bored pile, Bearing capacity
Dynamic load test
Driving energy

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Information
  • Publisher :Korean Geosythetics Society
  • Publisher(Ko) :한국지반신소재학회
  • Journal Title :Journal of the Korean Geosynthetics Society
  • Journal Title(Ko) :한국지반신소재학회 논문집
  • Volume : 18
  • No :3
  • Pages :89-100
  • Received Date : 2019-08-13
  • Revised Date : 2019-09-25
  • Accepted Date : 2019-09-25
  • DOI :https://doi.org/10.12814/jkgss.2019.18.3.089
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