ABSTRACT
Continuum theories such as elasticity and plasticity have been applied to analyze the behavior of soil in the engineering length scale, and the classical theories have been extended to a generalized one to include a granular structure such as a Cosserat body and/or a higher order strain gradient dependent model. In particular, extended models such as the Cosserat model and strain gradient-dependent models are presented in some detail since they are considered to be continuum theories in which particulate nature of granular materials can be taken into account as a first order approximation. The volume change caused by plastic deformation is often called dilatancy, which is considered to be one of the characteristics of granular materials. However, the stress-strain rate relationships based on the associated flow rule usually produce a huge volume expansion owing to this dilatancy, particularly for a large value.
