Study on Dynamic Characteristics and Electromagnetic Signal Variation Characteristics of Coal Under Impact Loading

In order to reveal the dynamic properties and electromagnetic signal variation characteristics of outburst coal seam, the dynamic mechanical properties of coal samples under impact loading were studied by using SHPB bar technology with a cross section of 50 mm. The results show that with the increase of strain rate, the dynamic response of coal materials transits from hardening to softening, and the coal samples are destroyed. The electromagnetic signal released during the process lasts less than 1 seconds and its frequency ranges from 0 Hz to 40 Hz. The electromagnetic signal shows the characteristics of straight-line rise, exponential decline and small oscillation at the end, and increases with the increase of impact velocity, average strain rate and maximum strain rate, while decreases with the increase of failure strain.