Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Study on the Effectiveness of Preloading Method on Reinforcement of the Pile Foundation by 3D FEM Analysis

3차원 수치해석을 이용한 공동주택 수직증축용 기초 보강 선재하공법 효과 분석

  • Wang, Cheng-Can (Dep. of Geospace & Geotechnical Engrg., Univ. of Science & Technology) ;
  • Han, Jin-Tae (Korea Institute of Civil Engrg. and Building Technology) ;
  • Jang, Young-Eun (Dep. of Geospace & Geotechnical Engrg., Univ. of Science & Technology) ;
  • Ha, Ik-Soo (Dept. of Civil Engrg., Kyungnam Univ.) ;
  • Kim, Seok-Jung (Korea Institute of Civil Engrg. and Building Technology)
  • 왕성찬 (과학기술연합대학원대학교(UST) 지반신공간공학과) ;
  • 한진태 (한국건설기술연구원) ;
  • 장영은 (과학기술연합대학원대학교(UST) 지반신공간공학과) ;
  • 하익수 (경남대학교 토목공학과) ;
  • 김석중 (한국건설기술연구원)
  • Received : 2017.11.23
  • Accepted : 2017.12.11
  • Published : 2018.01.31
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Abstract

In recent years, vertical extension remodeling of apartment building is considered as one of the efficient ways to broaden and enhance the utilization of existing buildings due to the rapid development of population and decrement of land resources. The reinforcement of foundation is of great importance to bearing the additional load caused by the added floors. However, because of the additional load, the carried load by the existing piles would be in excess of its allowable bearing capacity. In this study, a conceptual construction method called preloading method was presented. The preloading method applies force onto the reinforcing pile before vertical extension construction. The purpose of preloading is to transfer partial load applied on the existing piles to reinforcing piles in order to keep each pile not exceeding the allowable capacity and to mobilize resistance of reinforcing pile by developing relative settlement. The feasibility and effect of preloading method was investigated by using finite numerical method. Two simulation models, foundation reinforcement with preloading and without preloading, were developed through PLAXIS 3D program. Numerical results showed that the presented preloading method is capable of sharing partial carried load of existing pile and develops the mobilization of reinforcing pile's frictional resistance.

최근, 수직증축을 통한 공동주택의 리모델링은 제한된 부지 내에서 세대수를 증가시킬 수 있다는 장점으로 인해 그 수요가 증가하고 있다. 수직증축시 기초보강의 가장 큰 목적은 증축되는 층고로 인해 발생하는 추가하중을 지지하는 것이다. 단, 추가된 하중의 일부가 보강말뚝이 아닌 기존말뚝에도 가해지기 때문에, 기존말뚝의 허용지지력을 초과하지 않는 범위 내에서만 증축이 가능하다. 선재하공법은 수직증축 시공 전 단계에서 기존말뚝에 가해지던 하중 중 일부를 보강말뚝에 분담하도록 하여, 증축하중이 추가되어도 기존말뚝의 허용지지력을 초과하지 않도록 하며, 선재하 하중에 의해 보강말뚝의 침하를 미리 발생시켜 증축하중이 가해졌을 때 보강말뚝의 지지력을 빨리 발현시키는 공법이다. 본 연구에서는 3차원 수치해석을 통해 선재하공법의 효과를 분석하였다. 3D FEM 프로그램인 PLAXIS 3D를 활용하여 수직증축 리모델링시 기초보강을 모델링하고 선재하공법의 적용 유무에 따른 효과를 비교 분석하였다. 수치해석 결과 선재하공법을 적용하였을 때 기존말뚝에 가해지던 하중을 보강말뚝에 더욱 효과적으로 분담하였으며, 보강말뚝의 지지력이 조기에 발현하는 데 효과가 있는 것으로 확인하였다.

Keywords

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