Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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3-D Numerical Analysis for the Verification of Bearing Mechanism and Bearing Capacity Enhancement Effect on the Base Expansion Micropile

선단 확장형 마이크로파일의 3차원 수치해석을 통한 지지 메커니즘 및 지지력 증대효과 검증

  • Lee, Seokhyung (Dept. of Infrastructure Safety Research, Korea Inst. of Civil Eng. and Building Tech.) ;
  • Han, Jin-Tae (Dept. of Infrastructure Safety Research, Korea Inst. of Civil Eng. and Building Tech.) ;
  • Jin, Hyun-Sik (Hydraulic and Geotechnical Consultants) ;
  • Kim, Seok-Jung (Dept. of Infrastructure Safety Research, Korea Inst. of Civil Eng. and Building Tech.)
  • 이석형 (한국건설기술연구원 인프라안전연구본부) ;
  • 한진태 (한국건설기술연구원 인프라안전연구본부) ;
  • 진현식 ((주)에이치앤지컨설턴트) ;
  • 김석중 (한국건설기술연구원 인프라안전연구본부)
  • Received : 2021.02.09
  • Accepted : 2021.02.20
  • Published : 2021.02.28
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Abstract

Micropiles are cast-in-place piles with small diameters. The advantage of micropile is low construction expense and simple procedures, so it is widely applied to existing buildings and structures for the reinforcement of foundation and seismic performances. The base expansion structure has been developed following the original mechanism of horizontal expansion steps under compressive loading. This kind of structure can be installed at the pile end to improve the bearing capacity by tip area enlargement and horizontal force increment to the pile surface area. However, 'Micropile with base expansion structure' cannot be put into practical use, because detailed verification for the developed technique has not been conducted so far. In this research, 3-D numerical analysis was conducted to figure out the bearing mechanism of base expansion micropile and to verify the bearing capacity improvement compared to the general micropiles. 3-D modelling of micropile with base expansion structure was carried out and input parameter was determined. Bearing mechanism induced by base expansion structure was analyzed by lab-scale modelling, and bearing capacity improvement was verified by field-scale analysis.

마이크로파일은 소구경 현장타설말뚝으로 간단한 시공법과 비교적 저렴한 공사비용으로 각종 건축물 및 구조물 기초보강 및 내진보강 등에 활용되고 있다. 말뚝 선단에 단순한 메커니즘의 고정 지압 구조체를 장착하여, 상부하중 작용 시 지압구가 압축·팽창하면서 선단 면적의 확대와 주면으로의 쐐기수평력을 발휘하여 지지력을 증대시키는 "선단 확장형 마이크로파일"이 개발되었으나, 개발된 공법에 대한 정확한 검증이 부족하여 실제 현장에서 활용되지 못하고 있는 실정이다. 이에 본 연구에서는, 선단 확장형 마이크로파일의 지지 메커니즘과 일반 마이크로파일 대비 지지력 증대효과를 검증하고자 3차원 수치해석을 수행하였다. 선단 확장형 마이크로파일을 모델링하고 수치해석을 위한 입력 물성치를 산정하였으며, Lab-scale 수치해석을 통하여 고정 지압 구조체가 압축·팽창되면서 발현되는 수평력에 의한 지지 메커니즘을 확인하였다. 이와 더불어 Field-scale 수치해석을 통해 일반 마이크로파일과의 지지력을 비교·검증한 결과, 압축 및 인발지지력이 각각 20.0%와 38.9% 증대되는 것을 확인하였다.

Keywords

Acknowledgement

본 연구는 한국건설기술연구원의 '건축물 내진성능 향상을 위한 선단 확장형 마이크로파일 개발' 과제의 지원으로 수행되었으며, 이에 감사드립니다.

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