Three-Dimensional Elasto-Plastic Analysis for Soils.

Abstract : This report presents accomplishments in perfecting the elasto-plastic constitutive equations of Hardin (1978) and their implementation into EPSAP (elasto-Plastic Soil Analysis Program). Essential features of soil behavior that result from the soil skeleton being particulate are included in the soil model. It is recognized that the plastic behavior of particulate materials depends on direction of the effective stress increment as well as state of effective stress. Two classes of stress increment directions are defined with different plastic potential and hardening functions for each class. Specific research dealt with: 1) crushing of soil particles; 2) modeling soil strength in terms of effective stress; 3) modifications of the Class 1 plastic potential function; 4) modeling work softening behavior for Class 1 plastic hardening; 5) formulating a model for triaxial compression of soils including construction and analysis of the database; 6) development of the theory and basis for defining Class 1 hardening in terms of triaxial compression; 7) modeling Class 2 plastic hardening; 8) formulating models for one-dimensional strain in soils including construction and analysis of the database. 9) development of the theory and basis for defining Class 2 hardening in terms of 1D-strain.