Interesting question. If you place a heavy load on ice,measured in pressure, the ice there melts. One example is the pressure under a blade of an ice skate. When is that pressure so low that there is no melting and the skate doesn't side? Now mix in some clay and it becomes more complicated.
the strength of ice depends on the temperature. Bearing in mind that adfreeze shear is the more reliable strength parameter and also bearing in mind that there's a reason ice skating works. The pressure being applied actually reduces the strength.
They can support some fairly good loadings if stiff or very stiff. This can increase with freezing and can reduce with applied loading and thaw under pressure (a feature of ice called regulation). Depending on the soil particle size and the type of clay particle, they can have supercooled liquid in them at -40C/F.
