Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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A Comparison Study between Top-down Load Test and Bi-directional Load Test Analysis Method in Rock-socketed Small Size Drilled Shaft

암반소켓된 소구경 현장타설말뚝의 정재하시험과 양방향재하시험 분석법 비교연구

  • Song, Myungjun (Hyundai Engineering & Construction Co., Ltd. R&D division) ;
  • Song, Younghun (Hyundai Engineering & Construction Co., Ltd. R&D division) ;
  • Jung, Minhyung (Hyundai Engineering & Construction Co., Ltd. R&D division) ;
  • Park, Youngho (Hyundai Engineering & Construction Co., Ltd. R&D division) ;
  • Park, Jaehyun (Korea Institute of Construction Technology Geotechnical Engineering Research Division) ;
  • Lee, Juhyung (Korea Institute of Construction Technology Geotechnical Engineering Research Division) ;
  • Chung, Moonkyung (Korea Institute of Construction Technology Geotechnical Engineering Research Division)
  • Published : 2013.09.01
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Abstract

In this study, each top-down load test and bi-directional load test has been performed on the 480mm diameter of two rock socketed drilled shafts, which are located next to each other, and the results have been compared. The result shows that the settlement from the equivalent load-settlement curve of bi-directional load test is smaller than one from top-down load test, because elastic is not considered in equivalent load-settlement curve of bi-directional load test. Therefore elastic shortening should be considered to obtain appropriate equivalent load-settlement curve. Three existing methods used to obtain equivalent load-settlement curve with consideration of elastic shortening has been compared with the result of top-down load test. The result shows that those existing methods are sufficiently applicable to the design. In addition, result of comparison between top-down load test and bi-directional load test shows that bi-directional load test was found to overestimate bearing capacity because it does not consider pile body failure.

이 논문에서는 정재하시험과 양방향재하시험의 하중-침하거동을 비교하기 위하여 인접한 위치에서 직경 480mm인 암반에 소켓된 현장타설말뚝을 시공하고 각각 정재하시험과 양방향재하시험을 실시하였다. 양방향재하시험 해석법 중 기존의 탄성압축량을 고려하지 않은 등가하중곡선법은 정재하시험 결과와 비교할 경우 침하량을 과소평가하는 것으로 나타났기 때문에, 정확한 하중-침하 곡선 산정을 위해서는 반드시 탄성압축량을 고려해야 한다. 또한 기 제안된 여러 탄성압축량을 고려한 등가하중곡선법들을 정재하시험 결과와 비교검토한 결과, 충분한 적용성을 가지는 것으로 판단되었다. 또한 정재하시험과 양방향재하시험의 지지력을 비교한 결과, 양방향재하시험은 말뚝재료의 극한강도를 반영하지 못하고 지반의 극한지지력만을 평가하므로 반드시 재료강도에 대한 검토를 실시하여야 한다.

Keywords

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