Slug Test Analysis in Vertical Cutoff Walls with Consideration of Filter Cake

The Bao Nguyen, Chulho Lee, Hangseok Choi

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In constructing a vertical cutoff wall, bentonite-water slurry is frequently used to maintain the stability of sidewalls during excavation before backfilling the trench with less permeable materials to complete the cutoff wall construction. This procedure leads to a thin but relatively impermeable layer, called a filter cake, on the excavation surface. The aim of this paper is to examine the effect of a filter cake on evaluating hydraulic conductivity of the cutoff wall backfill through a slug test analysis with the aid of the verified numerical program, Slug_3D. As an upper bound solution for evaluation of the hydraulic conductivity of the cutoff wall backfill, no-flux boundary conditions for the boundaries of cutoff walls are imposed to consider the effect of filter cakes. The type-curve method and modified line-fitting method are employed to reanalyze the case of EMCON/OWT, Inc., as an example. The previous analysis, without consideration of a filter cake, is compared with the current results that consider the filter cake to reveal the necessity of considering the effect of a filter cake in the slug test analysis. The comparison shows that the hydraulic conductivity of the cutoff wall backfill will be underestimated in a slug test analysis if the filter cake is not properly considered.

Original languageEnglish
Pages (from-to)785-797
Number of pages13
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume137
Issue number8
DOIs
Publication statusPublished - 2011 Aug 3

Keywords

  • Backfills
  • Bentonite
  • Core walls
  • Filters
  • Hydraulic conductivity

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Environmental Science(all)

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