Critical state soil mechanics

Critical State Soil Mechanics is the area of soil mechanics that encompasses the conceptual models that represent the mechanical behavior of saturated remolded soils based on the Critical State concept.

The Critical State concept is an idealization of the observed behavior of saturated remoulded clays in triaxial compression tests, and it is assumed to apply to undisturbed soils. It states that soils and other granular materials, if continuously distorted (sheared) until they flow as a frictional fluid, will come into a well-defined critical state. At the onset of the critical state, shear distortions ${\displaystyle \ \varepsilon _{s}}$ occur without any further changes in mean effective stress ${\displaystyle \ p'}$, deviatoric stress ${\displaystyle \ q}$ (or yield stress, ${\displaystyle \ \sigma _{y}}$, in uniaxial tension according to the von Mises yielding criterion), or specific volume ${\displaystyle \ \nu }$:

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