The deformation of columnar ($2) saline ice under triaxial compression was investigated at a temperature of-10 °C and a constant strain rate of 3.9×10−5 s−l using a true multiaxial testing system. The ice was proportionally loaded under confinement ratios of R21=σ22/σ11=0.25 and R31=σ33/σ11 which varied between 0 and 1. The stresses σ11 and σ22 are normal stresses applied in two orthogonal directions across the columns and σ33 was applied along the columns. The behavior of the ice was macroscopically ductile and most of the deformation occurred perpendicular to the direction of the columns, which is consistent with deformation through basal slip. The flow curve is characterized by a linear region with an ill defined yield point and by a slowly varying post-yield region. The ice exhibited a small amount of across-column cracking under all along-column confinements. Volume was generally not conserved. The triaxial yield stress σl l, y and the triaxial peak stress σ11.p can be described by Hill's (1950) criterion for the failure of plastically orthotropic materials.
This work contributes to that need. It deals specifically with $2 ice because it is from such a material that first-year ice sheets are made. Ice undergoes a ductile-to-brittle transition as the rate of loading increases. Smith and Schulson (1994) showed that a truncated Coulombic-type failure criterion describes the biaxial brittle failure stress of $2 saline ice when compressed across the columns, and Schulson and Nickolayev (1995) demonstrated that Hill's (1950) criterion describes its ductile failure stress under similar loading. Gratz and Schulson (1996) showed that the brittle compressive failure stress of $2 saline ice under moderate triaxial loading can be described by a similar Coulombic criterion, and both Hausler (1983) and Timco and Frederking (1986) attempted to describe its ductile failure stress under such loading in terms of n-type yield functions.
