Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Analysis of Piled Raft Bearing Capacity Increase with Centrifuge Test

원심모형시험을 통한 Piled Raft 기초의 지지력증가 특성 분석

  • Park, Dong-Gyu (School of Civil and Environmental Eng, Yonsei Univ.) ;
  • Choi, Kyu-Jin (School of Civil and Environmental Eng, Yonsei Univ.) ;
  • Kim, Dong-Wook (Geotechnical Engineering Research Division, Korea institute of construction technology) ;
  • Chung, Moon-Kyung (Geotechnical Engineering Research Division, Korea institute of construction technology) ;
  • Lee, Jun-Hwan (School of Civil and Environmental Eng, Yonsei Univ.)
  • Received : 2012.03.14
  • Accepted : 2012.07.16
  • Published : 2012.08.31
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Abstract

In the conventional design of a piled raft, the axial resistance offered by the raft itself is typically neglected and only that of the group pile is accounted in estimating the total axial resistance of the piled raft. As a consequence, piled rafts are usually designed conservatively by neglecting the raft resistance. In this study, a series of centrifuge model tests have been performed to compare the axial behavior of a group pile with that of a piled raft (both having 16 component piles with an array of $4{\times}4$) in sands with different relative densities and in clays with different preconsolidated pressures. The test results revealed that, with respect to the allowable settlement of 25 millimeters for bridge foundations, the piled raft resistances were greater than those of the group pile by 13% for dense sand, by 22% for loose sand, by 30% for stiff clay, and by 22% for soft clay. Furthermore, the ratio of piled raft resistance to group pile resistance increased as the settlement increased.

말뚝지지 전면기초는 무리말뚝 기초뿐만 아니라 전면기초까지도 연직력에 대하여 효과적으로 저항하기 때문에 지지력의 증가, 부등침하의 감소, 전체 침하량 억제 등의 장점이 있어 경제적인 기초형식으로 간주될 수 있다. 그러나 실제 말뚝지지 전면기초의 설계 및 설계 기준에 있어 전면기초의 지지력을 고려하고 있지 않기 때문에 전면 기초에 의한 지지력 증가 및 침하량 억제 효과는 고려되지 못하는 실정이다. 본 연구에서는 말뚝지지 전면기초의 거동특성을 분석하고 전면기초에 의한 지지력 증대효과를 정량화하기 위하여 원심모형시험을 수행하였다. 이를 위해 말뚝지지 전면기초, 무리말뚝기초, 전면기초, 단독 말뚝기초 등 각 기초형식에 대해 별도의 실험을 수행하였으며, 말뚝지지 전면기초의 지지력 특성 변화를 분석하고 다른 기초형식의 지지력 특성변화 분석 결과와 비교하였다.

Keywords

References

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