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Research Article

A Fundamental Study on Evaluation of Corrected Compression Index by Plasticity Index in Marine Clayey Soils

해성 점성토의 소성지수에 따른 보정압축지수 평가에 관한 기초연구

Seong-Bak Park1
,
Kang-Il Lee2*
,
Se-Gwan Seo1
박 성백1
,
이 강일2*
,
서 세관1
1Member, Managing Director, N-Genius Co., Ltd., 4-22 Naebang-gil, Bogae-myeon, Anseong-si, Gyeonggi-do 17508, Republic of Korea
2Member, Professor, Dept. of Civil Engineering, Daejin Univ., 11-1 Hoguk-ro, Pocheon-si, Gyeonggi-do 11159, Republic of Korea
Member, Research Director, Zian Company ltd., 8th Woosuk University Headquarters Building, 443 Samrye-Ro, Samrye-Eup, Wanju-Gun, Jeollabuk-Do 55338, Republic of Korea
* Corresponding Author
30 September 2018. pp. 9-18
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Abstract

The soil parameters important for the design of the soft ground are the compression index (Cc), the consolidation settlement and consolidation speed at the field. Compression index is obtained by laboratory consolidation test. In the laboratory consolidation test, sample disturbance always occurs. In order to correct the disturbance phenomena, the method of calculating the compression index proposed by Schmertmann (1955) is generally used. However, recent developments in sampling technology and Korean soil conditions are different from those proposed by Schmertmann. So it needs to be verified. In this study, each consolidation curve’s cross void ratio is evaluated by doing consolidation test varying disturbance on high-plastic clay (CH), low-plastic clay (CL) and low-plastic silt (ML). The test results were 0.521e0 for low-plastic silt, 0.404e0 for low-plastic clay, and 0.458e0 for the high-plastic clay. This results were different from those of Schmertmann’s suggested value of 0.42e0. Therefor we proposed a correction formula using the plastic index according to soil type. However, since the results of this study are limited test results, further studies on various korean soil are needed to suggest the compression index correction method according to the degree of plasticity index of soil.

Keywords
Corrected compression index
Plasticity index
Oedometer test
Disturbed clay
Soil classification

연약지반 설계에 중요한 지반정수는 압축지수(Cc)이며, 현장의 압밀침하량 및 압밀침하속도를 산출하는데 필요하다. 이러한 압축지수 산정은 실내압밀시험을 통해 얻어지는데, 실내압밀시험에서는 반드시 시료교란이 발생하며, 이러한 교란현상을 보정하기 위하여 Schmertmann(1955)이 제시한 보정 압축지수 산정방법이 일반적으로 사용되고 있다. 그러나 최근 시료 샘플링기술의 발전과 국내 지반조건 등이 Schmertmann이 제시한 것과 상이하므로 이에 대한 검증이 필요하다. 이에 본 연구에서는 저소성 실트(ML), 저소성(CL) 및 고소성 점토시료(CH)에 대하여 교란도를 변화시켜 압밀시험을 실시하여 각각의 압밀곡선의 교차 간극비를 평가하였다. 시험결과 저소성 실트(ML)의 경우 0.521e0, 저소성 점토(CL)의 경우 0.404e0, 고소성 점토(CH)의 경우 0.458e0로 산정되어, Schmertmann이 제시한 0.42e0의 보정값과 다른 결과를 확인하였으며, 흙의 종류에 따른 소성지수(PI)를 활용한 보정식을 제안하였다. 그러나 본 연구결과는 한정된 지역에서의 시험결과이므로 흙의 소성도에 따른 압축지수 보정방법을 제시하기 위해서 다양한 국내 점토에 대한 후속연구가 필요할 것으로 판단된다.

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Information
  • Publisher :Korean Geosythetics Society
  • Publisher(Ko) :한국지반신소재학회
  • Journal Title :Journal of the Korean Geosynthetics Society
  • Journal Title(Ko) :한국지반신소재학회 논문집
  • Volume : 17
  • No :3
  • Pages :9-18
  • Received Date : 2018-07-31
  • Revised Date : 2018-09-12
  • Accepted Date : 2018-09-15
  • DOI :https://doi.org/10.12814/jkgss.2018.17.3.009
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