Experimental Investigation of Suffusion in Dam Core Soils of Glacial Till

The main objectives of this study were to determine the susceptibility to suffusion of widely graded, non-plastic glacial till; to identify potential factors influencing susceptibility; and conversely, to determine grading characteristics that potentially eliminate suffusion susceptibility. A laboratory experimental program was performed on 12 non-plastic glacial till specimens. Four were natural glacial tills sourced from the cores of four existing embankment dams in Sweden, and the remaining eight were mixtures based on these tills with adjusted particle size distributions to obtain target gradations. Four specimens failed by suffusion. By comparing against stable specimens, these were characterized by fines content <20 %, sand fraction <25 %, and finer fraction <30 %. Conversely, gradations with higher fines content (>25 %), which in this study corresponds to finer fraction >35 %, may provide additional limits to suffusion susceptibility of this kind of soil.