A Discrete Numerical Simulation Of Micromechanics For Dense Coal Granular Systems: Implication For Coal And Gas Outbursts

Coal and gas outbursts mostly occur in tectonic coal occurrence areas. Tectonic coal can be seen as an aggregate of particles. In this study, the discrete element method is used to investigate mechanical properties of tectonic coal under biaxial loading. The results are as follows: Macroscopically, the stress and strain of tectonic coal exhibit strain-softening and volumetric shrinkage, and shear failure is observed during loading. Microscopically, the inner porosity of the shear band is greater than that on the outside. The particle movement and the structural variation of force chains in the shear zone lead to rising porosity. The elastic potential energy stored in the particle system is calculated, accounting for about 1/7 of the external work. Most of the external work is consumed by particle friction. This characteristic is significant for understanding the effect of ground stress in gas outbursts, as well as gas desorption coupled with coal instability. (c) 2021 Published by Elsevier B.V.