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Evaluation of Rocking Mechanism for Embedded Shallow Foundation via Horizontal Slow Cyclic Tests

수평반복하중 실험을 이용한 근입된 얕은 기초의 회전거동 메커니즘 평가

Kil-Wan Ko1
,
Jeong-Gon Ha2
,
Heon-Joon Park3
,
Dong-Soo Kim4*
고 길완1
,
하 정곤2
,
박 헌준3
,
김 동수4*
1Member, Graduate Student, Dept. of Civil & Environmental Engrg., KAIST
2Member, Graduate Student, Dept. of Civil & Environmental Engrg., KAIST
3Member, Research Prof., Dept. of Civil & Environmental Engrg., KAIST
4Member, Prof., Dept. of Civil & Environmental Engrg., KAIST
1정회원, 한국과학기술원 건설 및 환경공학과 석사과정
2정회원, 한국과학기술원 건설 및 환경공학과 박사과정
3정회원, 한국과학기술원 건설 및 환경공학과 연구교수
4정회원, 한국과학기술원 건설 및 환경공학과 교수
*교신저자. *Corresponding Author. 
31 August 2016. pp. 47-59
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Abstract

Rocking behavior of shallow foundation reduces the superstructure load during earthquake. However, because of deficiency of understanding of rocking mechanism and soil permanent deformation, it has not been applied to real construction. In this study, slow cyclic tests were conducted for embedded shallow foundations with various slenderness ratio via centrifuge tests. From the variation of earth pressure ‘soil rounding surface’ phenomenon which makes maximum overturning moment equal to ultimate moment capacity was observed. Rocking and sliding behavior mechanism was evaluated. Also, nonlinear behavior and energy dissipation increase as rotation angle increases. And ultimate moment capacity of embedded foundation is larger than that of surface foundation. Finally, adequate ultimate moment capacity can be suggested for seismic design through this study.

Keywords
Rocking foundation
Slow cyclic test
Shallow foundation
Ultimate moment capacity
Rocking mechanism
Embedded foundation

얕은 기초의 회전거동은 지진 시 상부 구조물의 지진하중을 줄이는 효과적인 방법으로 대두되고 있다. 그러나 회전거동의 메커니즘에 대한 이해부족과 항복거동으로 인한 지반변형 때문에 시공에 적용되지 못하고 있다. 본 연구에서는 원심모형실험을 이용한 수평반복하중 실험을 통해 세장비가 다른 시스템의 근입된 얕은 기초의 회전거동 특성을 평가하였다. 실험결과를 통해 기초의 회전거동으로 인한 하부지반면의 원형현상을 관찰하였으며, 이로 인해 기초의 최대 전도모멘트가 기초의 극한 모멘트 지지력과 같아지는 것을 알 수 있었다. 기초 저면에서 관측된 토압변화를 통해 항복거동으로 인한 수평거동과 회전거동의 연결(coupling)과 분리(decoupling)현상을 볼 수 있었다. 또한 기초의 회전각이 증가할수록 지반의 비선형성과 에너지 감쇠가 커짐을 알 수 있었고, 근입된 기초의 극한 모멘트 지지력이 지표면에 놓인 기초의 극한 모멘트 지지력보다 더 커지는 것을 확인하였다. 본 연구를 통해 기초의 회전거동을 이용한 내진 설계 시 보다 정확하고 적절한 기초의 극한 모멘트 지지력을 제시할 수 있을 것이라 판단된다.

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 32
  • No :8
  • Pages :47-59
  • Received Date : 2016-05-31
  • Revised Date : 2016-08-04
  • Accepted Date : 2016-08-06
  • DOI :https://doi.org/10.7843/kgs.2016.32.8.47
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