Simulation of triaxial test data on Auckland residual soil using a bubble stress-strain model

This paper presents an application of a bubble model (a non-linear multi-surface kinematic hardening soil model), implemented in the FLAC software, to simulate the stress-strain behaviour measured in an undrained triaxial compression of Auckland residual clay. The workings of the model are explained in a qualitative manner and the differences between this model and modified Cam clay model are explained. It is shown that the model represents the overall stress-strain behaviour of the soil well. The extent of the small strain elastic behaviour is controlled by the size of the bubble. The results show that the softening just beyond the bubble is too severe and that further work is needed to optimise the selection of values for plastic modulus part of the bubble model.