Effects of brine content on the strength of frozen Ottawa sand

Strength of frozen saline soils

“…content is observed. However, the strengths presented by Ogata et al (1983) and Pharr and Merwin (1985) were significantly higher since the strain rates used in their studies were more than 50 times those used in this study. …”

“…4 represents the (1 -R) value for 8, = 1. The c values for the sand from this study and the Ottawa sand tested by Pharr and Merwin (1985) are of the same order of magnitude (0.67 vs. 1.02).…”

“…The amount of unfrozen water is controlled by the initial pore fluid salinity and soil temperature. The unfrozen water content increases with increasing temperature and salinity generally resulting in a decrease in strength (Ogata et al 1983;Pharr and Merwin 1985;Stuckert and Mahar 1984). Ogata et al (1983) suggested that for granular soils, the unfrozen water content provides a method for predicting the compressive strength at temperature warmer than the eutectic point (-2 1.3"C for NaCl).…”

“…For cohesive (fine-grained) soils, Ogata et al (1983) observed that using only the unfrozen water content did not provide a unique relationship for different soil types and that the thickness of the unfrozen water film could be used to better explain the decrease in strength with an increase in unfrozen water content. Pharr and Merwin (1985) used the concept of volumetric brine content, v,, to predict the behavior of saline S is the salinity of solution before freezing; pi is density of ice at given temperature; and S,, p, are the salinity and the density of brine in equil i b r~u m with ice at given temperature (from phase diagram). The review of previous works suggests that a further understanding of the relationship between unfrozen water content and strength is needed for both saline and nonsaline frozen soils.…”

“…First, the best fit between the measured unfrozen water content and strength will be established using linear polynomial regressions. Secondly, the approach proposed by Pharr and Merwin (1985) based on the use of a brine porosity within the frozen soil will be examined. Figure 16 shows the variation of strength versus measured unfrozen water content for each soil.…”