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2016 Vol.32, Issue 12 Preview Page
Unfrozen Water Content and Unconfined Compressive Strength of Frozen Soils according to Degree of Saturations and Silt Fractions

포화도와 실트 함량에 따른 동결토의 부동 수분량 및 일축압축강도 특성

Sang Yeob Kim1
,
Won-Taek Hong1
,
Seung Seo Hong2
,
Yong Baek3
,
Jong-Sub Lee4*
김 상엽1
,
홍 원택1
,
홍 승서2
,
백 용3
,
이 종섭4*
1Member, Ph.D. Candidate, School of Civil, Environmental, and Architectural Engrg., Korea Univ.
2Senior Researcher, Korea Institute of Civil Engrg. and Building Technology
3Member, Research Fellow, Korea Institute of Civil Engrg. and Building Technology
4Member, Prof., School of Civil, Environmental, and Architectural Engrg., Korea Univ.
1고려대학교 건축사회환경공학과 박사수료
2한국건설기술연구원 수석연구원
3한국건설기술연구원 연구위원
4고려대학교 건축사회환경공학과 교수
*교신저자. *Corresponding Author. 
31 December 2016. pp. 59-67
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Abstract

The strength of frozen soils is affected by size and shape of particles, and the amount of ice and unfrozen water. The objective of this study is to characterize the unfrozen water content and the unconfined compressive strength of the frozen soils according to the degree of saturations and silt fractions. The specimens are mixtures of sand, silt, and water. The silt fractions (SF), which are the ratio of the silt weight (Wsilt) to the sand weight (Wsand), are 10% and 30%. In addition, the degrees of the saturation are 5%, 10%, 15%, and 20%. The specimens are frozen under the temperature of -10°C conditions. The uniaxial compression tests are conducted for 24 hours, 48 hours, and 72 hours after freezing to determine proper freezing time. The freezing time of 24 hours is chosen because the unconfined compressive strengths of specimens after 24 hours freezing times are similar to each other. Furthermore, the unfrozen water content is monitored during freezing using the TDR system. The unfrozen water content increases with the increase of the silt fraction and degree of saturation. The unconfined compressive strength of the frozen soils exponentially increases with increasing the degree of saturation. This study shows that the amount of ice has more influence on the strength of the frozen soils than the amount of unfrozen water.

Keywords
Degree of saturation
Frozen soils
Ice
Silt fraction
TDR
Unfrozen water
Unconfined compressive strength

동결토의 강도는 흙 입자의 크기와 모양, 그리고 얼음과 부동 수분의 양과 같은 요인에 영향을 받는다. 본 연구에서는 동결토의 포화도와 실트 함량에 따라 변화하는 부동 수분의 양과 강도를 평가하고자 하였다. 시료는 주문진사, 실트, 그리고 증류수를 혼합하여 사용하였다. 실트의 함량비(SF)는 주문진사의 중량(Wsand)에 대한 실트 중량(Wsilt)의 비율이 10%와 30%가 되도록 혼합하고, 포화도는 5%, 10%, 15%, 그리고 20%가 되도록 조성하였다. 시료는 -10°C의 챔버 내에서 동결하였고, 동결 시간을 선정하기 위하여 24 시간, 48 시간, 그리고 72 시간동안 동결한 시료에 대하여 일축압축실험을 수행하였다. 일축압축강도가 동결 시간 24 시간 이후에 유사하여 동결 시간은 24 시간으로 선정하였다. 또한, 동결 과정 중 부동 수분의 양을 파악하기 위해 TDR 시스템을 이용하여 시료의 함수비를 모니터링 하였으며, 실트의 함량과 포화도가 증가함에 따라 부동 수분의 양이 증가하였다. 동결이 완료된 시료에 대하여 일축압축실험을 수행하였고, 포화도의 증가에 따라 일축압축강도가 지수함수적으로 증가하는 것으로 나타났다. 포화도가 증가함에 따라 부동 수분의 양이 증가하였으나, 동결에 사용된 물 즉, 얼음이 강도 발현에 보다 큰 영향을 미친 것으로 판단된다.

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 32
  • No :12
  • Pages :59-67
  • Received Date : 2016-09-01
  • Revised Date : 2016-10-12
  • Accepted Date : 2016-11-07
  • DOI :https://doi.org/10.7843/kgs.2016.32.12.45
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