Analysis of progressive damage and energy consumption characteristics of gas-bearing coal under cyclic dynamic loads

To explore the mechanical responses and failure patterns of coal samples subjected to various gas pressures and cyclic dynamic loads, a split Hopkinson pressure bar (SHPB) test system of gas-bearing coal was used to conduct cyclic impact tests on the coal samples. The findings indicate that: 1. With an increase in the initial gas pressure (0-0.5-1 MPa), the dynamic strength of the coal samples progressively drops. 2. The number of dynamic load cycles sustained by a coal sample under an impact velocity of 3 m/s and a gas pressure of 0 MPa is six, while that at an impact velocity of 5 m/s and a gas pressure of 1 MPa is two, indicating that the number of dynamic load cycles sustained by coal samples shows an overall decreasing trend under the coupling effect of dynamic load and gas. 3. The larger the impact velocity, the higher the resulting gas pressure. After the second impact, the dynamic strength of coal samples (at an impact velocity of 5 m/s and a gas pressure of 1 MPa) decreases from 45.7 MPa to 32.7 MPa, and its dynamic mechanical strength reduces by as much as 28.88 %. 4. The energy dissipation during the dynamic impact of coal samples is around 0.2–0.35 J/cm3, 0.3–0.5 J/cm3, and 0.5–0.7 J/cm3, when the impact velocity increases steadily from 3 m/s to 5 m/s, respectively, showing a gradually ascending trend. 5. An expression for determining the dynamic disaster of gas-bearing coal-rock under cyclic disturbance is proposed, which has significant guiding relevance for evaluating dynamic disasters involving coal-rock gas.