Particle Breakage: Exploring the numerical and experimental approaches in crushable soil mechanics

The breakage phenomenon has gained attention from geotechnical and mining engineers primarily due to its pivotal influence on the mechanical response of granular soils. Numerous researchers performed laboratory tests on crushable soils and incorporated the corresponding effects into numerical simulations. A systematic review of various studies is crucial for gaining insight into the current state of knowledge and for illuminating the required developments for upcoming research projects. The current state-of-the-art study summarizes both experimental evidence and numerical approaches, particularly focusing on discrete element simulations and constitutive models used to describe the behavior of crushable soils. The review begins by exploring particle breakage quantification, delving into experimental evidence to elucidate its influence on the mechanical behavior of granular soils, and examining the factors that affect the breakage phenomenon. In this context, the accuracy of various indices in estimating the extent of breakage has been assessed through ten series of experiments conducted on different crushable soils. Furthermore, alternative breakage indices are suggested for constitutive models to track the evolution of particle crushing under continuous shearing. Regarding numerical modeling, the review covers different approaches using the discrete element method (DEM) for simulating the behavior of crushable particulate media, discussing the advantages and disadvantages of each approach. Additionally, different families of constitutive models, including elastoplasticity, hypoplasticity, and thermodynamically based approaches, are analyzed. The performance of one model from each group is evaluated in simulating the response of Tacheng rockfill material under drained triaxial tests. Finally, new insights into the development of constitutive models and areas requiring further investigation utilizing DEM have been highlighted.