Experimental and numerical investigation on the dynamic damage behavior of gas-bearing coal

The study of the dynamic mechanical properties of gas-bearing coal and its mechanical feedback is of great importance for coal mining operations. Herein, we investigate the influence of methane pressure on the mechanical and dynamic failure properties of gas-bearing coal. Dynamic impact experiments were performed and analyzed numerically with a modified Holmquist-Johnson-Cook (HJC) model. In addition, the dynamic failure behavior and deformation mode of gas-bearing coal samples are examined in detail. The experimental and simulation results showed that (1) higher methane pressure at the same impact velocity led to a greater fractal dimension factor of crushed coal; (2) methane gas can weaken the elastic modulus, mechanical strength, and strain rate of coal and influence its dynamic damage characteristics; (3) under the same methane pressure, a higher impact velocity results in drastically more severe damage in gas-bearing coal, and a transition from tension-compression failure to compression stress dominated failure was observed with the increasing impact velocity; and (4) higher methane pressures resulted in more significant damage. A method for determining the HJC parameters of gas-bearing coal is presented, and mechanical alterations in coal triggered by interactions with methane are simulated. This research provides an improved understanding of complex and catastrophic underground dynamic disasters.