Soil Mechanics and Work-Hardening Theories of Plasticity

Soils having cohesion and internal friction are often considered to be perfectly plastic solids. A consistent approach has been proposed on the basis of the mathematical theory of perfect plasticity, and several interesting results were obtained. However, such an idealized treatment will often result in a marked difference between prediction and experimental fact. In particular, the strong dependence of the volume change under shearing action on the prior history of the soil cannot be properly taken into account. It is suggested herein that soil be treated as a work-hardening material which may reach the perfectly plastic state. A remarkable qualitative agreement is then obtained with the known behavior of soils in triaxial tests; additional study along similar lines appears most promising.