Testing and constitutive modelling of the mechanical behaviours of gravelly soil material

In this study, large-scale triaxial compression tests are conducted on gravelly soil material. The experimental investigation shows that gravelly soil exhibits complicated volume-dilatation/contraction behaviours that are dependent on stress level. To better describe the mechanical behaviours, an elastoplastic constitutive model is proposed within the frameworks of generalised plasticity and the critical state soil mechanics. An evolution equation of the void ratio is incorporated into the model to describe the effect of a relatively dense or loose state on the volume-change behaviours. The model has 10 material constants that could be determined using a few large-scale conventional triaxial tests. The model is then used to simulate the mechanical behaviours of gravelly soil. Comparisons between the numerical simulations and the test data show that the model is capable of capturing the mechanical behaviours of gravelly soil under various confining pressures. This research can be beneficial for understanding the mechanical behaviours of gravelly soils.