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Characteristics of Bentonite Filter Cake on Vertical Cutoff Walls Evaluated by Modified Fluid Loss Test

수정 fluid loss 시험을 이용한 연직 차수벽에 생성된 벤토나이트 필터케익 특성 평가

  • Nguyen, The-Bao (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Park, Moon-Seo (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Lim, Jee-Hee (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Choi, Hang-Seok (School of Civil, Environmental, and Architectural Engrg., Korea Univ.) ;
  • Han, Shin-In (R&D Center, Seoyeong Engrg. Co., Ltd.)
  • 웽테바오 (고려대학교 건축.사회환경공학부) ;
  • 박문석 (고려대학교 건축.사회환경공학부) ;
  • 임지희 (고려대학교 건축.사회환경공학부) ;
  • 최항석 (고려대학교 건축.사회환경공학부) ;
  • 한신인 ((주)서영엔지니어링 연구소)
  • Received : 2010.10.01
  • Accepted : 2011.01.06
  • Published : 2011.02.28

Abstract

During the construction of vertical cutoff walls, filtration of bentonite slurry into the adjacent soil formation fabricates a layer of bentonite filter cake on the wall surface. The bentonite filter cake possesses much lower hydraulic conductivity compared to that of backfill materials in the cutoff wall. Hydraulic conductivity of bentonite filter cakes formed with three different types of bentonites has been measured by performing the modified fluid loss test under various pressure levels. Three different mixture ratios, 4, 6, and 8%, were selected for fabricating bentonite filter cakes to represent common field conditions. Two analysis methods for interpreting the experimental data from the modified fluid loss tests were employed to estimate hydraulic conductivity of the bentonite cakes. The range of hydraulic conductivities of the three bentonite cakes is between $2.15{\times}10^{-11}\;m/s$ and $2.88{\times}10^{-10}\;m/s$ which is 1 to 2.7 orders of magnitude lower than that of the design cutoff wall backfill. The stress distribution and thickness of the bentonite cakes were also evaluated in this paper.

Acknowledgement

Supported by : 학술진흥재단, 한국건설교통기술평가원

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