| Summary: | Although extensively used as core material in dams in many parts of the world, internal instability and suffusion potential of glacial till is still a relatively unexplored field. Statistically, dams with cores of glacial till have higher frequency of internal erosion incidents than dams with other types of core soils. Such potential overrepresentation may stem back to the erodibility of the glacial till itself. One mechanism that may be influential is suffusion due to internal instability. The literature offers several methods to evaluate a soils vulnerability to this mechanism, however, in terms of glacial till soils; the validity of assessment criteria is unclear. An offset in applicability may, at best, provide too conservative guidance, but at worst, it may be misleading, confusing or erroneous. Thus, the applicability of available state-of-the-art criteria for internal instability of glacial till soils is investigated in this paper. Using gradations from: laboratory tests performed by the author at Luleå University of Technology; gradations from experimental suffusion tests in the literature; and gradations from existing dams, a total of 36 glacial till gradations are evaluated. The study indicates that the approach by Kenney-Lau and its Li-Fannin adaptation provide predictions relatively more accurate in identifying glacial till gradations with unstable performance due to suffusion. Godkänd; 2015; 20150515 (hayrof)
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