Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Analysis of the Shaft Resistance of a Pile Embedded in Sand Responding to Ground Deformation by Model Tests of Simulated Ground Heaving

실내모형실험을 통한 지반 융기시 사질토 지반에 매설된 지반 변형 대응형 말뚝의 주면 마찰 저항 분석

  • Shin, Sehee (Dept. of Civil and Environmental Eng., Incheon National Univ.) ;
  • Lee, Kicheol (Corporate Affiliated Research Institute, UCI Tech Co., Ltd.)
  • 신세희 (인천대학교 건설환경공학과) ;
  • 이기철 (유씨아이테크(주) 기술연구소)
  • Received : 2022.09.29
  • Accepted : 2023.01.30
  • Published : 2023.01.31
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Abstract

The pile driving process may lead to ground heaving, causing additional positive skin friction to act on the piles, compromising their stability. This study proposes a new pile foundation type that can reduce positive skin friction. This was investigated by designing and constructing a pile with a hydraulic cylinder which actively responds to ground deformation. The newly proposed pile design was compared against traditional piles in multiple model tests where ground heaving was simulated. In the tests, base load and total shaft resistance were measured during ground heaving and with expansion of the hydraulic cylinder. As a result of the tests, a very small amount of expansion of the hydraulic cylinder member completely reduced the positive skin friction and increased the base load. Excessive expansion of the hydraulic cylinder, however, generates negative skin friction beyond the zero skin friction state. Therefore, it is necessary to estimate the appropriate level of hydraulic cylinder expansion, taking into account the amount of ground heaving and the allowable displacement of the pile.

말뚝이 근입된 지반의 융기는 말뚝에 추가적인 상향 주면 마찰력을 발생시켜 말뚝의 안정성을 저해할 수 있다. 본 연구에서는 말뚝의 일부에 지반 변형에 능동적으로 대응 가능한 부재가 삽입되어 말뚝에 작용하는 상향 주면 마찰력을 감소시킬 수 있는 새로운 말뚝 기초 양식을 제안하였다. 제안된 말뚝의 실효성을 검증하기 위하여 지반 변형 대응 부재로서 유압 실린더가 적용된 말뚝을 설계 및 제작하였다. 일반 말뚝과 제안된 말뚝을 대상으로 지반 융기 모사 실험을 수행하여 선단 하중, 주면 마찰력과 지반 변형 대응 부재의 팽창량에 따른 선단 하중의 변화를 분석하였다. 실험 결과, 매우 적은 양의 실린더 부재의 팽창에도 말뚝에 작용하는 인발 마찰력이 완전히 상쇄되며 이에 따라 선단 하중이 증가하였다. 그러나 실린더 부재의 과도한 팽창은 상향 마찰력의 감소를 넘어 부주면 마찰력을 발생시키므로 지반 팽창량 및 말뚝의 허용 변위를 고려한 적절한 지반 변형 대응 부재의 팽챵량 산정이 필요하다.

Keywords

Acknowledgement

본 연구는 국토교통과학기술진흥원의 지원으로 수행되었으며(21CTAP-C157021-02), 이에 깊은 감사를 드립니다.

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