Influence of Low Temperature Oxidation of Coal Body on Dynamic Disasters of Coal and Rock During Coal Seam Gas Extraction

In order to study the evolution process of coal and rock dynamic disaster during gas drainage and to understand the mechanism of low-temperature oxidation of coal body, the influence of low temperature oxidation on coal rock power disasters in gas extraction was evaluated by means of water retention measuring porosity method, P wave velocity measurement, initial velocity of gas release and strength coefficient of coal rock. The results show that with the increase of the oxidation temperature of coal, the coal quality and the velocity of P-wave continuously decrease, the internal fractures develop gradually and the porosity increases by 73.3%; the structure of coal body is destroyed by the development of coal, and the firmness coefficient decreases with the increase of the oxidation temperature of the coal body; on the contrary, the fracture of the coal body provides the channel for the gas release, contrary to the solid coefficient of the coal body. The initial velocity of the gas dissipation with the coal oxidation temperature increases, and the rate of increase gradually increases. The low temperature oxidation process of coal body will lead to the decrease of coal body strength and the increase of gas emission pressure, which will lead to a significant increase of the comprehensive forecast index K of gas outburst and the possibility of coal rock dynamic disaster.