Stress analysis of crack characteristic of anthracite under dynamic loading

The coal dynamic characteristic stress identification under dynamic load is important for guiding underground mineral mining and predicting underground dynamic disasters. In this article, the dynamic compression test of anthracite under five strain rates is carried out, the evolution law of three kinds of crack characteristic stress is analyzed, and a prediction model of the crack characteristic stress threshold considering the strain rate effect is established. Then, the rationality of crack characteristic stress under dynamic loading is discussed from the damage evolution standpoint, and the crack extension response mechanism during dynamic compression of anthracite is discussed. The result shows that the crack characteristic stress threshold is significantly influenced by the strain rate. The three characteristic stress thresholds are positively correlated with the strain rate, but the ratios to the crest stress gradually decrease. The increase in the strain rate strongly contributes to the crack extension behavior of anthracite. In the crack unstable extension phase, because of the increase of the strain rate, anthracite shows more energy dissipation under the same deformation in association with the stress concentration effect and the dynamic strength enhancement effect. The crack propagation rate is increased, the crack propagation path of the section is more complex, and more severe damage occurs before the dynamic failure of anthracite, which leads to even more severe damage.