Constitutive model for soil-rock mixtures in the light of an updated skeleton void ratio concept

Abstract

As a type of special geological body, soil-rock mixtures (SRMs) are widely found in nature and used in civil engineering. Many structures, such as rockfill dams, highways and tunnels, have used SRMs as building materials. Proper modeling of SRMs is of great importance to capture the complex behavior of this heterogeneous material. In this manuscript, a simple constitutive model incorporating the skeleton void ratio concept is proposed for SRMs with varying soil contents (sc). A prominent feature of the model is a unified description of the behavior of SRMs with varying sc such that only model parameters of pure rock and of pure soil are required. After calibration, the model shows a good capacity to predict the stress–strain response of SRMs under a wide range of sc, void ratios, and confining pressures. In particular, it captures well the non-associated behavior of rock-dominated SRMs with different sc. Furthermore, the sc-value is shown to modify the plastic flow direction of the material without influencing its yield surface.