Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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The Analysis of Skin Friction on Small-scale Prebored and Precast Piles Considering Cement Milk Influence

시멘트풀의 영향을 고려한 축소모형 매입말뚝의 거동분석

  • 박종전 (연세대학교 토목환경공학과) ;
  • 정경자 (한국도로공사 도로교통연구원) ;
  • 정상섬 (연세대학교 토목환경공학과)
  • Received : 2016.09.09
  • Accepted : 2017.01.15
  • Published : 2017.01.31
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Abstract

Skin friction may be one of the most critical factors in designing the prebored and precast pile. Special attention was given to the interface behavior of cement milk-surrounding soil during the installation of prebored and precast pile. Small-scale field model pile test was conducted for the case of single pile. The size and geometry of the small-scale field model piles were designed with pile length 1.3m, boring diameter 0.067 m. Quick maintain-load test was conducted for the cases of boring diameter 150, 125, 90, 86, 74 mm and water-cement ratio 90, 70, 60%. It was shown that the bearing capacity of the pile increased as the cement-water ratio and cement milk thickness increased. Considering the scale effect between the small-scale model test and the actual construction site, it was found that cement milk thickness of 0.1~0.4D (50~200 mm) was reasonable for the stability of the structure. Also, the proper cement paste water / cement ratio was about 70% when considering the results of this study and quality control.

주면마찰력은 매입말뚝에서 가장 큰 영향 요소이다. 특히 시멘트풀과 지반 사이의 인터페이스 거동에 있어 가장 큰 영향을 미친다. 본 연구에서는 시멘트 풀 영향을 고려하여 단독말뚝에 대한 현장축소모형말뚝 재하시험을 수행하였다. 시험말뚝은 상사비를 고려하여 길이 1.3m 지름 0.067m로 선정하였으며, 굴착공경은 150, 125, 90, 86, 74mm, 시멘트풀 물/시멘트비는 90, 70, 60%로 급속재하시험을 수행하였다. 분석 결과 굴착공경이 증가할수록 지지력 증가를 확인하였다. 또한, 물/시멘트비가 부배합일수록 지지력이 증가하는 것을 확인하였다. 상사비를 고려한 축소모형시험결과, 굴착 공경은 말뚝지름(0.508mm 기준)보다 대략 0.1~0.4D(50~200mm) 크게 시공하는 것이 적합하다. 그리고 시멘트풀 물/시멘트비는 본 연구 결과와 품질관리 등을 고려하였을 때, 70% 정도가 적절하다.

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References

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