Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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A Study on the Bearing Capacitiy behavior of Large-diameter Drilled Shafts According to Various Ground Conditions under Pile Tip through Numerical Analysis Results

수치해석 결과 분석을 통한 다양한 말뚝 선단하부의 지반조건에 따른 대구경현장타설말뚝의 지지력 거동에 관한 연구

  • Kim, Chae Min (Dept. of Civil Engrg., Kyungsung Univ.) ;
  • Yun, Do Kyun (Dept. of Civil Environmental & Urban Engineering, Graduate School, Kyungsung Univ.) ;
  • Choi, Yongkyu (Dept. of Civil Engrg., Kyungsung Univ)
  • 김채민 (경성대학교 토목공학과) ;
  • 윤도균 (경성대학교 대학원 건설환경도시공학과) ;
  • 최용규 (경성대학교 공과대학 토목공학과)
  • Received : 2020.12.28
  • Accepted : 2021.11.04
  • Published : 2021.11.30
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Abstract

In this study, inverse analysis was performed on the bi-directional axial compressive load test conducted on drilled shafts. And the bearing capacities were analyzed by numerical analysis of various pile tip ground conditions of silt clay, silt sand, sand silt, sand gravel, weathered rock, and soft rock. The bearing capacities were analyzed using the P-S method, the Davisson method, and the allowable sttlement of 25.4 mm. The minimum allowable bearing capacities analyzed by three methods were found to be 19.64 MN ~ 24.96 MN. At this time, the base resistances were sharing a 2% ~ 12% of a head load, shaft resistance were shared 88% ~ 98% of the head load. The greater the strength of pile tip was found to increase the allowable bearing capacity. However, the difference between the maximum allowable bearing capacity and the minimum allowable bearing capacity was 5.32 MN, and the increase in the allowable bearing capacity was only 27% depending on the pile tip.

본 연구에서는 현장타설말뚝에서 실시된 양방향말뚝재하시험 자료에 대하여 역해석을 실시하였다. 그리고 실트질 점토, 실트질 모래, 모래질 실트, 모래질 자갈, 풍화암, 연암의 다양한 선단지반에 지지된 대구경 현장타설 말뚝에 대하여 수치해석을 실시하여 지지력을 분석하였다. 지지력 분석은 P-S 방법, Davisson 방법, 25.4mm 허용침하량을 이용하여 산정하였다. 3가지 방법으로 분석한 최소 허용지지력은 19.64MN ~ 24.96MN으로 나타났다. 이때, 선단지지력은 두부재하하중의 2% ~ 12%를 분담하였으며, 주면마찰력은 두부재하하중의 88% ~ 98%를 분담하였다. 선단 지반의 강도가 클수록 허용지지력이 증가하는 것으로 나타났다. 그러나 최대 허용지지력과 최소 허용지지력의 차이는 5.32MN로 선단 지반종류에 따른 허용지지력의 증가는 27%에 불과하였다.

Keywords

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