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2025 Vol.41, Issue 6 Preview Page
Analysis of Pile Foundation Behavior under Different Superstructure Load Conditions in Vertical Extension Remodeling

수직증축 리모델링 시 상부하중 형태에 따른 말뚝기초 거동 분석

Yu-Jin Noh1
,
Se-Na Eom2
,
Jong-Jeon Park3
,
Jung-Hwan Kim4
,
Jae-Hwan Lee5
,
Jun-Young Ko6*
노 유진1
,
엄 세나2
,
박 종전3
,
김 정환4
,
이 재환5
,
고 준영6*
1Integrated M.S./Ph.D. Program, Dept. of Civil Engineering, Chungnam National Univ.
2Integrated B.S./M.S. Program, Dept. of Civil Engineering, Chungnam National Univ.
3Member, Head of Seoul Branch, Ilshin Geological Engineering
4Member, Research Fellow, Dept. of Infrastructure and Technology Research, The Seoul Institute
5Member, Research Fellow, Dept. of Infrastructure and Technology Research, The Seoul Institute
6Member, Associate Prof., Dept. of Civil Engineering, Chungnam National Univ.
1비회원, 충남대학교 토목공학과 석·박사통합과정
2비회원, 충남대학교 토목공학과 학·석사연계과정
3정회원, 일신지질 서울지사 지사장
4정회원, 서울연구원 인프라기술연구실 연구위원
5정회원, 서울연구원 인프라기술연구실 연구위원
6정회원, 충남대학교 토목공학과 부교수
*Corresponding Author
31 December 2025. pp. 213-221
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Abstract

This study investigates the influence of superstructure load modeling and raft stiffness (rigid and flexible) on the behavior of piled raft foundations during vertical extension remodeling using three-dimensional finite element analysis with PLAXIS 3D. The ground profile consisted of weathered soil and weathered rock layers. The foundation system included a square raft measuring 18 m × 18 m × 1 m, 81 existing piles (PC piles), and 64 reinforcing piles (micropiles). Superstructure loads were modeled as Full Distributed Load (FDL), Column Load, Wall Load, and Partial Distributed Load (PDL; C100/C70/C50). Numerical analyses were performed according to the construction stages of vertical extension. The results indicate that, for a rigid raft, settlement was relatively uniform regardless of the load modeling method, and differences in pile axial forces compared with the FDL case were within 2% for existing piles and 18% for reinforcing piles. In contrast, a flexible raft exhibited pronounced differential settlement and increased axial forces in central piles under PDL conditions due to load concentration in the core area. These findings suggest that both superstructure load modeling and raft stiffness should be carefully considered when designing foundation reinforcement for vertical extension remodeling.

Keywords
Finite element method
Foundation reinforcement
Raft flexibility
Superstructure load condition
Vertical extension remodeling

본 연구에서는 수직증축 리모델링 시 상부하중 모델링 형태와 기초판의 강성 및 연성이 말뚝지지 전면기초 거동에 미치는 영향을 분석하고자 PLAXIS 3D를 이용한 유한요소해석을 수행하였다. 지반은 풍화토과 풍화암으로 구성하였고, 기초는 18m × 18m × 1m 기초판과 기존말뚝(PC 말뚝) 81본, 보강말뚝 64본(마이크로파일)로 구성하였다. 상부하중은 전체 등분포하중(FDL), 기둥하중(CL), 벽체하중(WL), 부분 등분포하중(PDL;C100/C70/C50)으로 고려하고, 수직증축 시공단계에 따라 해석을 수행하였다. 해석 결과, 강성 기초판에서는 하중 모델링 방식에 관계없이 침하량은 균등하고, 축력의 경우 전체 등분포 하중 대비 기존말뚝 2%, 보강말뚝은 18% 이내로 축력 차이가 발생하였다. 연성 기초판에서는 부분 등분포하중 조건에서 코어부 집중하중의 영향으로 부등침하 및 중앙부 말뚝의 축력이 크게 나타났다. 따라서, 수직증축 리모델링을 위한 보강 기초 설계 시 상부하중 모델링 형태와 기초판 특성을 함께 고려해야할 것으로 사료된다.

References
1

Ahmed, M., Mohamed, M.H., Mallick, J., and Hasan, M.A. (2014), “3D Analysis of Soil–foundation–structure Interaction in Layered Soil”, Open Journal of Civil Engineering, Vol.4, No.4, pp.305-318, https://doi.org/10.4236/ojce.2014.44032.

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2

Brinkgreve, R.B.J., Engin, E., and Swolfs, W.M. (2025), PLAXIS 3D User’s Manual, Bentley Systems, Delft, The Netherlands.

3

Hartman, I. (2023), Soil–structure Interaction Modelling of High-rise Building Settlements due to Compressible Soil Layers Below Foundation Level, Master’s Thesis, Delft University of Technology (TU Delft), Delft, The Netherlands.

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Kim, S.J., Wang, C.C., and Han, J.T. (2020), “Analysis of Load Distribution behavior in Vertical Extension Remodeling from Stiffness of Existing and Reinforcing Pile by Load Test”, Journal of the Korean Geotechnical Society, Vol.36, No.8, pp.61-72, https://doi.org/10.7843/kgs.2020.36.8.61.

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6

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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 : 41
  • No :6
  • Pages :213-221
  • Received Date : 2025-11-19
  • Revised Date : 2025-11-19
  • Accepted Date : 2025-11-19
  • DOI :https://doi.org/10.7843/kgs.2025.41.6.213
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