ABSTRACT
ABSTRACT: We investigate the quasistatic mechanical response of soils under monotonic loading using a discrete model of randomly generated convex polygons. The biaxial test is implemented using loading platens and confining stress applied though a membrane. These boundary conditions lead to strain localization as a typical mode of failure. Shear bands result from the buckling of chain forces, the length of those chain forces giving the characteristic width of the shear bands. The incremental response before failure is calculated from the numerical simulations. This response leads to nonlinear elasticity, non-associated plasticity, and instabilities strictly inside of the plastic limit surface. We explore the connection between the anisotropy of the contact network and the stiffness, and the role of the sliding contacts in the flow rule of plasticity.
