Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Cone Resistivity Penetrometer for Detecting Thin-Layered Soils

협재층 탐지를 위한 선단비저항 콘

  • Yoon, Hyung-Koo (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Jung, Soon-Hyuck (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Kim, Rae-Hyun (Civil Engrg. Group, POSCO Engrg. & Construction Co., Ltd.) ;
  • Lee, Jong-Sub (School of Civil, Environmental, and Architectural Engrg., Korea Univ.)
  • 윤형구 (고려대학교 건축.사회환경공학부) ;
  • 정순혁 (고려대학교 건축.사회환경공학부) ;
  • 김래현 (포스코건설 토목기술그룹) ;
  • 이종섭 (고려대학교 건축.사회환경공학부)
  • Received : 2010.02.11
  • Accepted : 2010.08.16
  • Published : 2010.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

The thin-layered sand seam in clay affects the soil behavior. Although the standard cone penetrometer (A: $10cm^2$) have been used to evaluate the thin-layered soil, the smaller diameter cone penetrometer have been commonly recommended because of the high resolution. The purpose of this study is the development and application of the Cone Resistivity Penetrometer (CRP), which detects qc, fs, and electrical resistivity at cone tip for the evaluation of thin layered soils. Two sizes of the CRP are developed for the laboratory and field test. The projected areas of CRP for the laboratory and field tests are $0.78cm^2$ (d: 1.0 cm) and $1.76cm^2$ (d: 1.5 cm), repectively. The length of friction sleeve is designed in consideration of ratio of the projected area to the friction sleeve area. The application tests are carried out by using the artificially prepared thin-layered soils in the laboratory. In addition, the field tests are conducted at the depth of 6 to 15 m in Kwangyang. In the laboratory test, the measured electrical resistivity and cone tip resistance detect the soil layers. Moreover, in the field test the CRP investigates the three thin-layered soils. This study suggests that the CRP may be a useful tool for detecting thin-layered in soft soils.

점토층 사이에 존재하는 모래 협재층은 연약지반 거동에 중요한 영향을 미친다. 협재층은 주로 표준 콘(단면적: $10cm^2$)에서 측정된 지반의 저항력과 간극수압 값을 이용하여 평가하고 있지만, 높은 해상도를 위하여 소형 콘이 널리 활용되고 있다. 본 논문의 목적은 연약지반에 얇게 분포된 협재층을 선단저항력, 주면마찰력 그리고 전기비저항을 이용하여 평가할 수 있는 전기비저항 콘(Cone Resistivity Penetrometer, CRP)을 개발하고 적용하는 것이다. CRP는 각각 실내실험(단면적: $0.78cm^2$, 직경: 1.0cm)과 현장실험(단면적: $1.76cm^2$, 직경: 1.5cm)에 활용되도록 제작하였으며, 길이는 표준 콘(단면적: $10cm^2$, 직경: 3.57cm)의 단면적과 마찰부의 면적비를 고려하여 제작하였다. 실내실험은 모래와 점토가 반복적으로 조성된 다층의 층상탐지 셀을 사용하여 각 지층의 경계면을 탐사하였으며, 현장실험은 광양지역에서 심도 6m부터 15m까지 관입실험을 수행하였다. CRP는 실내실험에서 측정된 선단저항력과 전기비저항으로 조성된 시료의 각 지층 경계면을 뚜렷하게 평가하였으며, 현장실험에서는 3개의 협재층을 탐지하였다. 본 연구에서 개발된 CRP는 실내 및 현장결과 적용성이 뛰어나 추후 유용하게 사용될 것으로 판단된다.

Keywords

References

  1. 김래현, 윤형구, 이우진, 이종섭 (2008), "광섬유를 이용한 온도 보상형 마이크로콘의 개발", 대한토목학회 논문집 29(4C), pp. 163-174.
  2. 김준한, 윤형구, 최용규, 이종섭 (2009), "전기비저항 콘 프로브를 이용한 해안 연약 지반의 간극률 산정", 한국지반공학회 논문집, 25(2), pp.45-54.
  3. 이종섭, 신동현, 윤형구, 이우진 (2008), "초소형 마이크로콘 관입 시험기의 개발 및 적용", 한국지반공학회 논문집, 24(2), pp.77-86.
  4. 윤형구, 김준한, 김래현, 최용규, 이종섭 (2008), "CRPT를 이용한 연약지반 협재층 탐지", 2008 지반공학회 가을 학술 발표회, pp.117-125.
  5. 한국지반공학회 (2005), "연약지반", 지반공학 시리즈, 구미서관.
  6. Ahmadi, M. M. and Robertson, P. K. (2005), "Thin-layer Effects on the CPT qc Measurement", Canadian Geotechnical Journal, 42(5), pp.1302-1317. https://doi.org/10.1139/t05-036
  7. Campanella, R. G. and Kokan, M. J. (1993), "A new approach to measuring dilatancy in saturated sands", Geotechnical Tesing Journal, ASTM, 16(6), pp.485-495. https://doi.org/10.1520/GTJ10288J
  8. Campanella, R. G. and Weemees, I. (1990), "Development and use of an electrical resistivity cone for groundwater contamination studies", Canadian Geotechnical Journal, 27, pp.557-567. https://doi.org/10.1139/t90-071
  9. Cho, G. C., Lee, J. S. and Santamarina, J. C. (2004), "Spatial variability in soils: high resolution assessment with electrical needle probe", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 130(8), pp.843-850. https://doi.org/10.1061/(ASCE)1090-0241(2004)130:8(843)
  10. De Lima, D. and Tumay, M. T. (1991), "Scale Effects in Cone Penetration Tests", Proceedings, Geotechnical Engineering Congress 1991, ASCE, Boulder, 1, pp.38-51.
  11. Hird, C. C., Johnson, P. and Sills, G. C. (2003), "Performance of Miniature Piezocones in Thinly Layered Soils", Geotechnique, 53(10), pp.885-900. https://doi.org/10.1680/geot.2003.53.10.885
  12. Hird, C. C. and Springman, S. M. (2006), "Comparative performance of $5cm^2$ and $10cm^2$ piezocones in a lacustrine clay", Geotechnique, 56(6), pp.427-438. https://doi.org/10.1680/geot.2006.56.6.427
  13. Horsnell, M. R. (1988), "The use of cone penetration testing to obtain environmental data", In penetration testing in the U.K. Institution of Civil Engineers, Thomas Telford, London, U. K., pp. 289-295.
  14. Lambe, T. W. and Whitman, R. V. (1979), "Soil Mechanics", John Wiley & Sons.
  15. Lunne, T., Robertson, P. K. and Powell, J. J. M. (1997), "Cone Penetration Testing in Geotechnical Practice", Blakie Academic, Great Britain, London.
  16. Roy, M., Tremblay, M., Tavenas, F. and La Rochelle, P. (1982), "Development of Pore Pressures in Quasi-Static Penetration Tests in Sensitive Clay", Canadian Geotechnical Journal, 19(2), pp. 124-138. https://doi.org/10.1139/t82-015
  17. Threadwell, D. D. (1976), "The influence of gravity, prestress, compressibility, and layering on soil resistance to static penetration", Ph.D. thesis, University of California at Berkeley, Berkeley, Calif.
  18. Titi, H. H., Mohammad, L. N. and Tumay, M. T. (2000), "Miniature cone penetration tests in soft and stiff clays", Geotechnical Tesing Journal, ASTM, 23(4), pp.432-443. https://doi.org/10.1520/GTJ11064J
  19. Yoon, H. K., Kim, J. H., Kim, R. and Lee, J. S. (2009), "Electrical Resistivity and Cone Tip Resistance Monitoring by Using Cone Resistivity Penetrometer", Proceedings of the Nineteenth International Offshore and Polar Engineering Conference, Osaka, Japan, pp.168-171.
  20. Zuidberg, H. M., Hoope, J. ten and Geise, J. M. (1988), "Advances in in-situ measurements", 2nd International Symposium on Field Measurements in Geomechanics, Sakurai, pp.279-291.