The steady state is exactly representing the critical void ratio under CSSM interpretation.
Year Researchers Developments 1940 Casagrande [11] Introduced critical void ratio, the same void ratio where contracted loose soil and dilated dense soil approach after sheared to large strains 1956 Taylor [12] Showed experimentally that dilatancy is stress dependent 1958 Roscoe et al.
The pressure-dependent critical void ratio [e.sub.cs] is expressed as
where [lambda] is the slope of the critical state line in the e - ln p' plane, [e.sup.[GAMMA]] corresponds to the critical void ratio for ln p' = 0, and p' is the mean effective pressure.
The critical void ratio of soil might be negative when the mean effective pressure p' in Equation (3) increases to a certain value, which is obviously unreasonable.