Soil Hinges: Macroscopic Evidence and Modeling Considerations

Abstract

The mathematical structure of a constitutive model might be defined as the collection of variables that it contains and the symmetries, relationships, dependencies, and independencies that are involved. Finding a structure that is appropriate for modeling a particular set of behaviors is probably as important as finding the right formulae to use for the relationships within the structure. This study explored whether a structure similar to one used in steel frame plasticity might apply to soils. Ample evidence was found that it does, to a good approximation. Evidence included data of transversely isotropic linear elasticity, which appears to be exhibited by most soils and which can hamper accurate prediction of settlements or of dynamic responses using isotropic models. Evidence also included data on yield points and plastic flow. Both normality and deviations from normality were shown to be deducible as consequences of the operation of soil hinges. Hinges were shown to be consistent with the familiar concept of a state boundary that is different from a yield surface, and with critical and steady states.