Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Development and Application of Ultra Small Micro-Cone Penetrometer

초소형 마이크로콘 관입시험기의 개발 및 적용

  • Lee, Jong-Sub (Dept. of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Shin, Dong-Hyun (Dept. of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Yoon, Hyung-Koo (Dept. of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Woo-Jin (Dept. of Civil, Environmental and Architectural Engrg., Korea Univ.)
  • 이종섭 (고려대학교 건축.사회환경공학과) ;
  • 신동현 (고려대학교 건축.사회환경공학과) ;
  • 윤형구 (고려대학교 건축.사회환경공학과) ;
  • 이우진 (고려대학교 건축.사회환경공학과)
  • Published : 2008.02.29
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Abstract

The disturbance zone and measured values are affected by the size of the penetrometer. The local value may be measured by the smaller penetrometer. An ultra small Micro-Cone penetrometer (5mm in outer diameter) is designed and manufactured to characterize soil properties with minimum disturbance during penetration tests. The tip resistance is measured by using stain gauges attached near the Micro-Cone. In addition, the friction sleeve is adopted to effectively remove the skin friction from the tip resistance. Design concern includes the installation of stain gauges, circuits, penetration systems, penetration rate, sampling rate, operating temperature, and calibration. Application tests show that the clay interface, and the soil layers consisting of clay and sand are clearly detected by the Micro-Cone. Furthermore, the cone tip resistances measured by the Micro-Cone and the miniature cone (16mm in outer diameter) are similar. Note the resolution is much higher in the Micro-Cone. This study shows that the Micro-Cone may effectively detect the soil interface with high resolution, and with minimum disturbance.

흙의 교란영역과 측정값은 관입시험기의 크기에 영향을 받는다. 관입기의 크기가 작을수록 더 국부적인 값을 얻을 수 있다. 관입시험 시 흙의 교란을 최소화하면서 흙의 특성을 파악하기 위하여 극소형 마이크로콘(외경 5mm)을 설계 및 제작하였다. 선단저항력은 마이크로콘 선단부에 설치된 변형률계를 이용하여 측정하였다. 뿐만 아니라 선단 저항력으로부터 마찰저항력 성분을 효과적으로 제거하기 위하여 이중관 형식의 마찰 슬리브를 채택하였다. 설계 시 변형률계의 설치, 회로구성, 관입시스템, 관입속도, 측정률, 작동 온도, 그리고 calibration 과정이 고려되었다. 점토의 경계면, 점토-모래지반의 경계면을 마이크로콘을 적용함으로써 효과적으로 찾아 낼 수 있었다. 뿐만 아니라, 마이크로 콘과 직경 16mm의 미니어처 콘을 이용하여 측정한 선단저항력이 매우 유사하지만, 마이크로 콘의 해상도가 매우 높은 것으로 나타났다. 본 논문은 마이크로 콘이 매우 높은 해상도 그리고 주변지반의 변형을 최소화하면서 흙의 경계면을 효과적으로 감지할 수 있음을 보여준다.

Keywords

References

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