关键词: 散粒体, 能量耗散, 抗转动, 离散元法

Abstract: Energy storing and dissipation are the underlying mechanisms of the macromechanical responses of granular materials subjected to shear failure, while they are difficult to measure in laboratory. We implemented a user-defined contact model considering rolling resistance to the commercial software PFC2D, and made a calculable method to count the energy components based on the first law of thermodynamics. Then the energy storing and dissipation through the whole sample are investigated in a series of numerical biaxial compression tests by discrete element method (DEM). Four kinds of friction are adopted, i.e. sliding and rolling (S-R), sliding and non-rolling (S-NR), non-sliding and rolling (NS-R) and non-sliding and non-rolling (NS-NR). The results show that the energy is mainly dissipated in the type of sliding rather than rolling. And at a small biaxial strain, the input energy is mainly stored as elastic energy with a small portion dissipated and the dissipated energy is globally distributed through the whole sample. While a large biaxial strain is achieved, the dissipated energy gradually turns dominant and the majority of energy dissipated in a narrow zone, showing the significant localization. In addition, the main direction in which the energy is dissipated shows strong anisotropy at all loading stages.

Key words: granular materials, energy dissipation, rolling resistance, DEM