An experimental study of the mechanism of coal and gas outbursts in the tectonic regions

Abstract

To reveal the mechanism of coal and gas outbursts in tectonic regions, a gas-driven multi-physics coal and gas outbursts experimental apparatus was developed. Based on the experimental results, the damage characteristics and the mechanism of outbursts of tectonic raw coal under different gas pressures and stress conditions are quantitatively investigated. The experimental results show that the damage to coal samples increases with the increase in gas pressure. When the gas pressure is 2.0 MPa, the damage to the coal sample tends to decrease with increases in the confining and axial stress. When the gas pressure exceeds the critical value of 2.2 MPa, a strong outburst phenomenon occurs, in which the pulverized coal is ejected and the outbursts cavern is blocked. However, when the gas pressure is 2.4 MPa, the coal samples are completely broken down after the tests, and the outbursts intensity becomes larger as the axial stress or the confining stress increases. In addition, the evolution of gas pressure and the degree of fragmentation of coal samples are also discussed quantitatively in the process of coal and gas outbursts. The present study of the mechanism of coal and gas outbursts in the tectonic regions is helpful for the assessment and forecasting of potential outbursts.