Modelling of Dynamic Soil Problems

Abstract

Some possibilities for the modelling of dynamic soil problems are described. Two basic features of constitutive models to be used in numerical analysis to simulate soil response under non-monotonic loading are: a description of the small strain elastic behaviour which will evolve and develop its own anisotropies as the stress or strain history unfolds; and provision for plasticity on reversal of stress or strain path. Laboratory geophysical techniques provide one possibility for tracking the evolution of stiffness anisotropy but have uncertainties of interpretation. Macroelement modelling is a form of numerical simulation using simple elemental systems which introduce important features from constitutive modelling. It lends itself to rapid parametric study of effects of geotechnical and seismic nonlinearity. Physical modelling can provide controlled data for validation of numerical modelling: the design of such models requires consideration of scaling laws. Results of some model tests on a single degree of freedom structure with a special isolating foundation are shown.