Experimental Study on Failure Characteristics and Energy Release Evolution of Coal Under Microwave Irradiation

In order to reveal the failure characteristics and burst tendency of coal after microwave irradiation, the microstructure damage effect of microwave irradiation on coal was explored. The microstructure damage, burst tendency and acoustic emission energy characteristics of coal samples before and after microwave irradiation were quantitatively evaluated, and the mechanisms behind porosity growth and the weakening effect of microwave irradiation were revealed. The results show that the damage amount DE of coal samples after microwave irradiation is 0.018, the crack damage amount DP is 0.015, and the crack damage amount accounts for 83.3% of the damage of coal samples. It is determined that the damage-weakening effect of microwave-irradiated coal is affected by the increase in cracks. The monitoring data show that the acoustic emission signals generated by its development are concentrated in the crack compaction stage and elastic stage, the energy dissipated by crack failure is proportional to the number of cracks, and the ability of coal samples to accumulate energy is inversely proportional to the number of cracks. After microwave irradiation, the mechanical properties of coal samples are weakened, the uniaxial compressive strength index is reduced by 67.66%, and the burst energy index is reduced by 66.67%, indicating that microwave irradiation can effectively reduce the bursting tendency of coal.