Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
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Evaluation of Mechanical Characteristics and Applicability of Clayey Sand by Fines Content

세립분 함유율에 따른 점토질 모래의 역학적 특성 및 적용성 평가

  • Jung-Meyon Kim (Department of Regional Infrastructure Engineering, Kangwon National Univ.) ;
  • Jun-Young Ahn (Department of Regional Infrastructure Engineering, Kangwon National Univ.) ;
  • Jae-young Heo (Department of Regional Infrastructure Engineering, Kangwon National Univ.) ;
  • Seung-Joo Lee (Korean Peninsula Infrastructure Special Committee, Korea Institute of Civil Engineering and Building Technology) ;
  • Young-Seok Kim (Northern Infrastructure Specialized Team, Korea Institute of Civil Engineering and Building Technology) ;
  • Beom-Soo Moon (Department of Regional Infrastructure Engineering, Kangwon National Univ.) ;
  • Yong-Seong Kim (Department of Regional Infrastructure Engineering, Kangwon National Univ.)
  • Received : 2023.05.30
  • Accepted : 2023.08.07
  • Published : 2023.09.30
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Abstract

In this research, laboratory tests were conducted on clayey sand (SC) to analyze its physical properties, compaction/permeability characteristics, and stress-strain behavior. The main objective was to determine the transitional fines content at which the mechanical properties of sand transition to those of clay, resulting in a change in the geotechnical behavior of the material. Additionally, to assess the practical applicability of SC soil, field data from a soft ground improvement site with significant settlement issues were collected. The settlement characteristics derived from laboratory tests and numerical simulations were then compared and analyzed in relation to the actual settlement data obtained from the field, aiming to evaluate the suitability of the SC soil as a compaction target layer. The laboratory tests and compaction analysis showed that the SC soil exhibited a distinct change in mechanical properties, shifting from sandy behavior to clayey behavior when the fines content exceeded 25%. This transition in mechanical behavior was found to be closely correlated with the content of clay particles within the material. Through numerical simulations of the soft ground site, it was verified that the use of clayey sand with a fines content exceeding the transitional level as a compaction target layer resulted in settlements that closely aligned with the measured settlements, with an average agreement of 91.2%. Based on these findings, it is deemed advisable to incorporate clayey sand with a fines content exceeding the transitional level as part of the compaction target layer in the design of soft ground improvements.

본 연구에서는 점토질 모래(SC)를 대상으로 실내시험을 수행하여 물리적 특성, 압밀/투수 특성, 응력-변형 특성을 분석하고, 세립분 함유량에 따라 모래에서 점토로 흙의 역학적 성질이 변화되는 전환 세립분 함유율을 도출하였다. 또한 현장 적용성 평가를 위해 실제 과다침하로 인하여 문제가 발생된 연약지반 개량 현장의 계측자료를 수집하여 실내시험 및 수치해석 결과를 바탕으로 도출된 침하특성과 현장에서 계측된 실제 침하특성을 비교·분석하여 SC의 압밀 대상층 적용성 평가를 수행하였다. 실내시험 및 압밀해석 결과 SC는 세립분 함유율 25%이상에서 사질토에서 점성토로의 역학적 특성 변화가 나타났으며, 점성 토로의 역학적 특성 전환은 점토입자의 함유율과 매우 밀접한 관계가 있는 것으로 나타났다. 연약지반 현장의 수치해석을 통해 전환 세립분 함유율 이상의 점토질 모래를 압밀 대상층으로 적용한 경우, 침하량이 계측침하량 대비 평균 91.2%로 거의 일치하는 결과를 확인하였다. 따라서 연약지반 설계에서 압밀대상층 범위 선정 시 전환 세립분 함유율 이상의 점토질 모래는 연약지반에 포함하여 적용하는 것이 바람직할 것으로 판단된다.

Keywords

Acknowledgement

This work was supported by National Research Foundation of Korea Grand Funded by the Korean Government(C1016725002).

References

  1. Dafalla, M. A. (2013), "Effect of clay and moisture content on direct shear tests for clay-sand mixtures", Journal of Advances in Materials Science and Engineering, Vol.2013, pp.1-8.
  2. Kenny, T. C. (1977), "Residual strengths of mineral mixture", Proc. of the 9th International Conference Soil Mechanics, Tokyo, pp.155-160.
  3. Kim, B. J., Kim, J. H., Jung, J. Y., Kwon, J. K. and Kim, T. H. (2016), "Characteristics of Sedimented Sandy in Nack-dong River Delta", Journal of the Korean Geotechnical Society, Vol.15, No.2, pp.25-33. https://doi.org/10.7843/kgs.2016.32.7.25
  4. Kim, J. M. (2018), Evaluation of Mechanical Characteristics and Applicability of Silty Sand and Clayey Sand by Fines Content, Ph.D Thesis, University of Kangwon, pp.3-11.
  5. Kim, U. G., Kim, D. W., Lee, J. Y. and Kim, J. H. (2012), "Evaluation of Cyclic Shear Strength Characteristics of Sands Containing Fines", Journal of the Korean Geotechnical Society, Vol.28, No.7, pp.1-40.
  6. Mitchell, J. K. (1977), Fundamentals of soil behaviour, 2nd Edition, John Wiley Interscience, New York, pp.172-189.
  7. Park, S. S. and Nong, S. S. (2014), "Effect of Sand Contents on Plastic and Liquid Limits and Shear Strength of Clays", Journal of the Korean Geotechnical Society, Vol.30, No.2, pp.65-76.