Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Effects of Raft Flexibility on the Behavior of Piled Raft Foundations in Sandy Soil

사질토에 근입된 말뚝지지 전면기초의 기초판 연성률에 따른 거동 분석

  • 송수민 (연세대학교 건설환경공학과) ;
  • 신종영 (연세대학교 건설환경공학과) ;
  • 정상섬 (연세대학교 건설환경공학과)
  • Received : 2023.02.02
  • Accepted : 2023.03.03
  • Published : 2023.03.31
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Abstract

The effect of raft flexibility on piled raft foundations in sandy soil was investigated using a numerical analysis and an analytical study. The investigation's emphasis was the load sharing between piles and raft following the raft rigidity (KR), end-bearing conditions. The case of individual piles and subsequently the response of groups of piles was analyzed using a 3D FEM. This study shows that the αpr, load-sharing ratio of piled raft foundations, decreases as the vertical loading increases and as the KR decreases. This tendency is more obvious when using friction piles compared to using end-bearing piles. The effect of raft rigidity is found to be more significant for the axial force distribution - each pile within the foundations has almost similar axial forces of the pile head with a flexible raft; however, each pile has different values with rigid rafts, especially with the end-bearing piles. The axial force of the pile base with floating piles shows similar point-bearing resistance for all the piles; however, it shows different values with end-bearing piles. The differential settlement ratio of rafts showed a larger value with lower KR.

본 연구는 기초판의 연성률이 말뚝지지 전면기초에 미치는 영향을 해석적 연구와 수치해석으로 분석했다. 기초판의 연성률(KR)과 선단지지 조건에 따른 말뚝과 기초판의 하중 분담률을 분석했다. 각각의 말뚝과 전체적인 응답은 3차원 유한 요소 해석법을 사용하여 분석했다. 본 연구에서 수직 하중이 증가하고 기초판의 연성률이 감소함에 따라 말뚝지지 전면기초의 하중분담비(αpr)가 감소하는 것으로 나타났다. 이러한 경향은 선단지지 말뚝을 사용하는 것보다 마찰말뚝을 사용하는 경우에 더 뚜렷하게 나타났다. 또한, 연성 기초판의 경우, 하중조건에 따른 말뚝 위치별 축력 분포경향은 큰 차이를 보이지 않았으나, 강성 기초판의 경우, 하중조건에 따라 외곽에 위치한 말뚝 두부 축력이 증가하는 경향을 보였다. 기초판의 침하는 연성 기초판 조건이 강성 기초판보다 더 크게 나타났으며, 이로 인해 연성 기초판 조건에서 하중분담비가 감소하는 것으로 나타났다.

Keywords

Acknowledgement

본 연구는 정부(교육부)의 재원으로 '한국연구재단의 기초연구사업(2018R1A6A1A08025348)'의 지원을 받아 수행되었으며, 이에 감사드립니다.

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