Cap Model Guided by Energy Concept

Abou-Sayed, A.S., and Yamada, S.E.
J Geotech Eng Div Ame Soc Civil Eng Proc V 105, No GT2, pg 183-200, Feb 1979.



The mathematical equivalence between the cap model in general and the constant pseudo-complementary energy surface defined by the stress deviation from a certain hydrostatic stress state is shown. This hydrostatic stress is proportional to the so-called “hardening parameter” in other literature. Consequently, the determination of a material parameter (the aspect ratio of the elliptical cap) is reduced to the measurement of the unloading elastic constants. Based on this analysis, a simple experimental approach to determine the parameters required for the cap model to represent polyaxial behavior of soils and rocks is presented