Low-threshold coal and gas outburst dynamic phenomenon and mechanism in Xinmi coal mining area

The mechanism and geological control of the low-threshold coal and gas outburst dynamic phenomenon in Xinmi coalfield were investigated from regional tectonic evolution, structural characteristics, "three soft" coal seam, gas occurrence and the gas desorption ability at initial stage. Our investigation revealed that the tectonic evolution of Xinmi coalfield was reformed by multistage tectonic activities, the "three soft" coal seam was widespread in the whole coalfield and controlled by gravitation gliding structure which was developed in extensional-chiasmic environment since Meso-Cenozoic. At the same time, the combined styles of "three soft" coal seam in gravitation gliding structure influences the gas occurrence and tectonic stress heterogeneous distribution; the scale and intension of coal-seam faults and rheology, and the development of tectonically deformed coal are the controlling factors of low-threshold coal and gas outburst dynamic phenomenon; the internal energy release of tectonically deformed coal in high stress environment is the key to low-threshold coal and gas outburst; the low-threshold coal and gas outburst area can be predicted by studying the rheology of coal seam and the early stage of gas desorption ability.