Effects of material properties on the mobility of granular flow

Abstract

In this study, we investigate the influence of material properties on the mobility of granular flow through granular column collapse experiments using the Smooth Particle Hydrodynamics method and a continuum constitutive model capable of describing the nonlinear responses of granular materials. Numerical simulations are systematically compared with available experimental data and well-established empirical laws to validate the capability of this numerical approach for simulating the dynamics of granular flow. Based on this validation, a series of numerical experiments is conducted to investigate the effects of strength properties (i.e. friction and dilation), density and stiffness properties (i.e. Young’s modulus and Poisson’s ratio) on the run-out distance and energy evolution of granular flows, which were unclear or contradictorily reported in previous experimental studies. We found that as the friction angle increases, the material is less mobilised and hence the run-out distance is shorter. In addition, a denser state (i.e. more dilation) facilitates its mobilisation associated with a greater volume expansion during the collapse. The density and stiffness properties of granular materials, nonetheless, have negligible effects on the deposit morphology and run-out distance of granular flow. To further quantify the effects of material properties, the run-out scaling law of granular flow, which describes the relationship between the run-out distance and the initial geometry of granular columns, is analysed and shown to be significantly influenced by the friction and dilation of the materials.