Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Analysis of Load Distribution Behavior in Vertical Extension Remodeling from Stiffness of Existing and Reinforcing Pile by Load Test

현장 재하시험을 통한 수직증축시 기존 말뚝과 보강 말뚝의 강성에 따른 하중분담거동 분석

  • Kim, Seok-Jung (Dept. of Infrastructure Safety Research, Korea Inst. of Civil Eng. and Building Tech.) ;
  • Wang, Cheng-Can (Dept. of Civil & Environmental Engrg., Univ. of Science & Technology) ;
  • Han, Jin-Tae (Dept. of Infrastructure Safety Research, Korea Inst. of Civil Eng. and Building Tech.)
  • 김석중 (한국건설기술연구원 인프라안전연구본부) ;
  • 왕성찬 (한국과학기술연합대학원대학교 건설환경공학) ;
  • 한진태 (한국건설기술연구원 인프라안전연구본부)
  • Received : 2020.05.18
  • Accepted : 2020.07.27
  • Published : 2020.08.31
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Abstract

It is generally considered that differences of axial stiffness between exiting pile and reinforcing pile affect the load distribution ratio during vertical extension remodeling. But there are few cases to verify the effect of stiffness by field load test on load distribution ratio in Korea. In this paper, a series of load tests for micropiles were carried out to evaluate the effect of axial stiffness on the load distribution ratio. First, different types of micropiles were constructed so that conventional micropiles simulated existing piles and waveform micropiles simulated reinforcing piles. Secondly, load tests were performed to evaluate the stiffness of each piles. After then, the raft was installed to make a piled raft system and load tests were applied on foundation to verify the effect of axial stiffness on the load distribution ratio. The experimental results show that the stiffness of waveform micropiles were 2.5 times larger than that of conventional micropiles, and the load distribution ratio between existing and reinforcing piles was increased according to axial stiffness of piles.

수직증축 리모델링시 상부 구조물의 구조적 안정성 확보를 위해서는 기초의 안정성이 우선적으로 확보되어야 한다. 수직증축형 리모델링 구조기준 고시(2014)에 따라, 수직증축시 기존 말뚝과 보강 말뚝의 강성에 따라 상부 하중을 분담하여 지지한다. 하지만, 국내에서는 증축시 활용할 수 있는 기초 보강공법 등에 대하여 연구 주제가 집중되어 있으며, 기존 기초와 보강 기초의 강성 차이에 의한 하중 분담율에 대한 연구는 미비하다. 따라서, 본 연구에서는 현장 재하시험을 통해 수직증축 리모델링시 기존 말뚝과 보강 말뚝의 강성에 따른 하중 분담 거동에 대하여 분석을 수행하였다. 서로 강성이 다른 일반 및 파형 마이크로파일을 시공하여 기존 말뚝과 보강 말뚝을 모사하고, 각각의 말뚝에 대한 재하시험을 수행하여 각 말뚝의 강성을 산정하였다. 그 후, 기존 말뚝과 보강 말뚝 두부를 연결하는 기초판을 타설하고 기초판 상부에 하중을 재하함으로써 기존 말뚝 및 보강 말뚝의 강성 차이에 따른 하중 분담 거동을 분석하였다. 그 결과, 파형 마이크로파일의 강성이 일반 마이크로파일에 비해 약 2.5배 크게 산정되었으며, 이에 비례하여 하중을 분담하는 것을 확인하였다.

Keywords

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