Description of flow of sand using state parameters

Abstract

The concept of “Critical State” as originally envisaged [1] is extended to include the influence of the third invariant of the stress deviation tensor. The concept of “Steady State of Flow” as proposed by Poulos and Castro [2,3] is also examined in some detail and it is concluded that the two concepts are substantially equivalent. It is pointed out that both nomenclatures are unfortunate: a more appropriate terminology is the “Ultimate State” as all samples when distorted far enough would ultimately tend to approach this state. The framework for a unified approach to the formulation of the constitutive law for cohesionless granular media utilizing the state parameters is discussed. Within this framework a number of observations such as the curvature of the yield surface and the state boundary surface and the laws of similarity under the so called 1-g testing conditions [4] are accounted for.