Dynamic mechanical response mechanism of prestatic-stressed coal under dynamic loading

Abstract

To explore the influence of dynamic impacts on the creep properties of underground pillars, an underground coal sample is selected as the research material, and the mechanical response characteristics under dynamic impact are explored by the split Hopkinson pressure bar and high-speed camera. The results show that (1) when the creep stress level is higher, the initial deformation of coal is greater, and the damage to the sample through long-term creep is more severe. (2) With increasing levels of static stress, the dynamic strength and elastic modulus of the coal sample first increase and then decrease, and the dynamic elastic modulus is positively correlated with the impact velocity. (3) The static stress level determines the process of crack propagation and the degree of fracture, while the external dynamic impact determines the propagation speed of the crack. The results of this research enrich the theory of control systems for the prevention of coal pillar failure and instability and provide a theoretical basis for safe and efficient mining of working faces.