한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

  • 제34권3호
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  • Pages.57-65
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  • 2018
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  • 1229-2427(pISSN)
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  • 2288-646X(eISSN)
한국지반공학회 (Korean Geotechnical Society)
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X-ray CT를 통한 사질토와 점성토의 간극수 동결 패턴 분석

Evaluation of Freezing Patterns for Sand and Clay by Using X-ray CT

  • 송준영 (연세대학교 건설환경공학과) ;
  • 이장근 (한국건설기술연구원) ;
  • 이성원 (한국건설기술연구원) ;
  • 이준환 (연세대학교 건설환경공학과) ;
  • 윤태섭 (연세대학교 건설환경공학과)
  • Song, Jun Young (Dept. of Civil and Environmental Engrg., Yonsei Univ.) ;
  • Lee, Jangguen (Korea Institute of Civil Engrg. and Building Technology) ;
  • Lee, Seong-Won (Korea Institute of Civil Engrg. and Building Technology) ;
  • Lee, Junhwan (Dept. of Civil and Environmental Engrg., Yonsei Univ.) ;
  • Yun, Tae Sup (Dept. of Civil and Environmental Engrg., Yonsei Univ.)
  • 투고 : 2018.02.02
  • 심사 : 2018.03.20
  • 발행 : 2018.03.31
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초록

본 연구에서는 사질토와 점성토 시료에 대하여 동결 시 내부 구조 변화를 고해상도 3차원 X-ray CT 이미징을 통해 정량적으로 평가하였으며, 동결 과정 중 온도 변화에 따른 탄성파 속도 측정을 통해 재료의 강성도 변화를 관찰하였다. 사질토의 경우 간극수 동결에 따른 내부 구조 변화는 관찰되지 않았으나, 점성토의 경우 시료의 동결 방향과 관계없이, 냉각원으로부터의 거리에 따라 두꺼운 얼음이 형성되는 것을 확인하였다. Two-point correlation 방법을 통해 시료의 동결 패턴을 정량적으로 분석한 결과, 냉각원으로부터의 거리에 따른 사질토의 대표단위길이(Lr)은 일정한 값을 가졌다. 반면 점성토의 경우 그 값이 선형으로 증가하는 경향을 보였으며, 시료 양 끝단의 대표단위길이는 약 2.5배의 차이를 보였다. 또한 동결 과정 중 사질토 시료 내 국부적 온도 차이는 관찰되지 않았으나, 상대적으로 낮은 열전도도를 갖는 점성토의 경우 국부적 온도 차이가 관찰되었으며, 온도 변화에 따른 재료의 강성 변화를 평가하였다.

This study adopts high resolution 3D X-ray CT imaging technique to visualize and evaluate the internal structure of experimentally frozen soils. Temperature and elastic wave velocity are also measured during the freezing process. The X-ray images of frozen specimens reveal that no changes in internal structure are observed for sand specimen, whereas systematic growth pattern of pore ice is observed within clay specimen. The freezing patterns are then quantified by a set of X-ray images with the aid of two-point correlation method by computing characteristic length Lr. The results reveal that characteristic length for pore ice freezing pattern in clay linearly increases with respect to the distance from the cooling source, so that Lr at the bottom layer is 2.5 times greater than the top layer when freezing process is completed. Furthermore, during the freezing process, local temperature differences are not observed in sand, but observed in clay specimen due to its relatively low thermal conductivity.

키워드

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