Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Analysis of Improved Shear Stiffness and Strength for Sandy Soils Treated by EICP

EICP 방법으로 처리된 사질토의 전단 강성도 및 강도 증가 분석

  • Song, Jun Young (Dept. of Civil and Environmental Engrg., Yonsei Univ.) ;
  • Ha, Seong Jun (Dept. of Civil and Environmental Engrg., Yonsei Univ.) ;
  • Jang, Jae Won (Dept. of Civil and Environmental Engrg., Hanyang Univ.) ;
  • Yun, Tae Sup (Dept. of Civil and Environmental Engrg., Yonsei Univ.)
  • 송준영 (연세대학교 건설환경공학과) ;
  • 하성준 (연세대학교 건설환경공학과) ;
  • 장재원 (한양대학교 건설환경공학과) ;
  • 윤태섭 (연세대학교 건설환경공학과)
  • Received : 2019.11.11
  • Accepted : 2020.01.16
  • Published : 2020.01.31
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Abstract

This study presents the experimental results of ground improvement efficiency induced by enzyme-induced carbonate precipitation (EICP) in soils. First, the optimal mixture ratio of EICP solution was determined by comparing the amount of induced carbonate depending on the different ratio among urea, CaCl2, and urease. Next, we evaluated the shear stiffness and strength of EICP-treated sandy soil by performing shear wave velocity measurement and triaxial shear test. Furthermore, induced carbonate in treated soil was visually investigated by X-ray CT and SEM analysis. The results showed that the maximum shear stiffness evolved 19~30 times after 6 hours of reaction time compared with non-treated sands. Also, the cohesion and the friction angle tended to increase and decrease, respectively, as the amount of induced carbonate increased.

본 연구는 효소에 의한 요소 분해를 통해 생성되는 탄산칼슘 침전(EICP)을 지반 내에 유도했을 때의 지반개량 효과를 실내실험으로 분석하였다. 먼저, EICP 용액의 최적 혼합비를 결정하기 위하여 용액 주 재료인 요소, 염화칼슘, 우레아제 농도를 달리했을 때 생성된 탄산칼슘 양을 비교하였다. 다음으로, 산정된 최적 혼합비의 EICP 용액으로 처리된 사질토의 전단 강성도 및 강도를 전단파 속도 측정과 삼축압축시험을 통해 평가하였다. 전단파 속도 측정은 EICP 반응 시간 동안 수행되었으며, 이를 통해 탄산칼슘 침전에 따른 전단 강성도의 발달을 확인할 수 있었다. 삼축압축시험은 압밀배수조건에서 EICP 처리된 시료 그리고 처리되지 않은 시료에 대하여 수행되어, 최종적으로 마찰각 및 점착력을 비교하였다. 마지막으로 X-ray CT 및 SEM 촬영을 통하여 EICP 처리된 시료 내의 탄산칼슘을 시각적으로 조사하였다. 실험 결과, EICP 반응 시작 후 6시간이 지나면 처리된 시료의 전단 강성도는 처리되지 않은 시료에 비하여 19~31배 증가하였다. 또한 EICP 반응에 의해 생성되는 탄산칼슘의 양이 증가할수록 점착력은 증가하는 반면 마찰각은 감소하는 경향을 관찰하였다.

Keywords

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