Variable modulus model for inelastic finite element analysis

A variable modulus modeling procedure for nonlinear analysis of soils is presented. The procedure accounts for stiffening behavior under volumetric strain, strain softening behavior under distortional strain, the influence of hydrostatic stress on shear strength, and the shear dilation effect. A numerical modeling process based on piecewise linear behavior (piecewise constant moduli) is used, without the use of analytical expressions for material properties. The modulus values are determined from the results of hydrostatic and triaxial tests. The theoretical basis of the method is presented, and the procedure for calculating the tangent moduli is described. Computational techniques for the state-determination problem and the linearization phase are developed and implemented in a general purpose computer program.