Model representation of sand tests

A non-associated plasticity model for friction materials was presented by Krenk (1999) and an efficient calibration procedure developed by Ahadi & Krenk (1999). The ability of the model to represent the behaviour of sand was verified by calibrating the model from different sets of triaxial drained tests for both loose and dense sand performed at different confining pressures. This
paper is a collection of calibration and prediction examples. The model was calibrated according to the procedure described in Ahadi & Krenk (1999) and results were compared to experimental data from Borup & Hedegaard (1995) and Ibsen & Jakobssen (1996). The obtained material parameters indicate that the shear modulus $G$
should increase with the mean stress, while the increase of the
bulk stiffness should be less than linear. The dependency on mean
stress is studied by fitting a power law function for both $G$ and
$kappa$. Finally prediction for undrained (constant volume) test
at different initial pressures are presented with material
parameter determined from drained triaxial test data.