Simulation and Experimental Study on the Discontinuous Dynamic Impact on Unidirectional Confined Coal‐Rock Damage

Abstract

The deformation and the damage characteristics of coal and rock under different restraint static load and different impact velocity were studied with the FEM software LS-DYNA. Based on this, the influence of impact load on the damage of coal rock under one-dimensional constraint condition was studied by using the self-developed constrained pendulum impact dynamic loading test device and ultrasonic testing device. The results show that the deformation of coal and rock increases with the increase of impact velocity and decreases firstly and then remains constant with the increase of constraint static load; when the constraint static load exceeds the compression strength, the displacement increases rapidly and the coal collapses at a strike; the damage quantity of coal and rock has a cumulative effect, and the damage quantity increases with the increase of impact number; when the constraint static load is identical, the increase of impulse contributes to microcrack propagation, and the damage quantity of coal and rock accelerates with the increase of single impact impulse; when the impulse is identical, the constraint static load restrains the microcrack propagation, and the damage quantity of coal and rock decelerates with the increase of constraint static load; the complete damage quantity range of coal and rock is 0.65∼0.75. In order to fully destroy the coal and rock, if the single horizontal impulse is greater, the number of shocks needed is less; if the constrained static load is greater, the more impact times are needed.

Dynamic Response of the Steel Plate Under the Impact of High-Speed Coal Projectile

“…It is difficult to observe the crater formation of the target plate through experiments, but the crater formation process of the target plate can be fully understood with the help of numerical simulation. Numerical simulation can qualitatively simulate the transient phenomenon of the projectile-steel plate interaction and give the numerical solution of the entire interaction process, which makes people have a clear and specific perceptual understanding of the armor-piercing process [20,21]. ere are few researches on the above process; in this study, the damage effects formed by coal-rock projectiles hitting steel plates of different thickness with different velocities in a forward direction were revealed based on the LS-DYNA numerical simulation method.…”

Research Progress of Coal Damage under Unsteady Load in China

“…Studies have simplified the related problems on the dynamic impact on coal and rock damage, that is, the effects of the impact load on coal. Primary cracks subsequently develop into macroscopic cracks [29].…”

“…The damage caused by the following is categorised into two categories, namely, "rapid jump" damage, which is caused by large tensile shear stress, and "slow stepped" damage, which is caused by the alternating tension-shear-compression-shear action. Wang et al [29] used the finite-element software LS-DYNA to investigate the deformation and damage charac-teristics of coal and rock under various constrained static loads and impact velocities and determined that coal damage increased with the increase in impact velocity and with the increase in constrained static load. Coal damage was first reduced and then remained unchanged.…”