Parameter Sensitivity Analysis of the Manzari-Dafalias Model for Modelling the Cyclic Response of a Sand

Abstract

In this paper, the numerical work that has been done to calibrate the Manzari-Dafalias model and to identify its more relevant parameters is presented. The model parameters, their respective reference values and the tests that were performed to determine most of the parameters are introduced. A parameter sensitivity analysis through numerical simulation of a triaxial monotonic drained test, using an OpenSees model with a single 1x1x1 m3 SSPbrickUP 3D element, is described and the results analyzed. The sensitivity analysis is conducted for each parameter individually, for several pairs of physically related parameters and of the most relevant ones. It is considered the final influence upon the peak values of the shear strain, shear stress ratio and dilatancy and upon the critical state volumetric strain. Furthermore, a parameter sensitivity analysis through numerical simulation of a cyclic undrained torsional test is implemented, both for the pre-liquefaction and liquefaction phases. In the former, the variation of some response parameters (namely the damping ratio, the shear modulus, the shear stress amplitude, the average shear stress, the shear strain amplitude and the average p) with the model parameters is evaluated for three different cycles.