Relationship between Porosity and the Constitutive Model Parameters of Rockfill Materials

Abstract

In this study, triaxial tests are performed on rockfill material (weakly weathered fresh tuff) with different porosities in order to obtain the stress–strain curves of the test specimens. The confining pressure and porosity are found to affect the rockfill material. The suitability of the Duncan–Chang model is assessed, and it is found that this model is not suitable for analyzing the mechanical behavior of rockfill materials with low porosities subjected to low confining pressures. Two models are proposed to overcome the limitations of the Duncan–Chang model: (1) an exponential–parabolic nonlinear elastic model, and (2) a modified Nanshui double yield surface model. Both of these models fit better with the stress–strain data obtained from experiments. Following this, regression models are developed to predict the parameters of the constitutive models as a function of the porosity of rockfill materials with high accuracy, which will enable researchers to obtain fast and reliable estimates of the parameters. The results can be used to lay the theoretical groundwork for finite-element simulations of rockfill dams, taking into account the differences in the constitutive model parameters due to spatial variability in the compaction quality of rockfill materials.