Compressive deformation and energy dissipation of crushed coal gangue

Crushed gangue, an inhomogeneous and discontinuous medium, is accompanied with the absorption and dissipation of energy under compression. In order to study the compressive deformation and energy dissipation of gangue in the loading process under conditions of different particle sizes, loading rates, and first-time stress loads, a SANS testing machine and steel cylinder were used to conduct experiments in this paper. The following conclusions were drawn from the investigation: 1) The gangue underwent three separate stages of compressive deformation, which included rapid, slow, and stable; 2) The energy density of the gangue increased nonlinearly as the strain increased, and the dissipated energy accounted for 10%, 20%, and 70% of the total energy, respectively, of the three compressive deformation stages; 3) Particle size and loading rate had significant effects on the deformation and energy dissipation of the gangue. The smaller the particle size or loading rate were, the more energy was required to produce the same level of deformation; 4) When the second stress load was smaller than the first-time stress load, the strain of the gangue increased approximately linearly. When the second stress load was greater, the strain of the gangue showed a logarithmic increase with the stress. Furthermore, under a greater first-time stress load, the gangue presented smaller strain under secondary compression, showed more resistance to deformation, and consumed more energy to produce the same deformation. (C) 2016 Elsevier B.V. All rights reserved.