Mechanism and Classification of Coal and Gas Outbursts in China

Abstract

Coal and gas outburst is a kind of complex dynamic disaster with short duration and strong explosiveness, and the modes and strength of the outburst are determined by the in situ stress, gas pressure, and physical and mechanical properties of the coal mass. In this paper, the status quo of research on the mechanism of coal and gas outburst in China is described from three aspects: the controlling effect of single factor, the controlling effect of multi-factor, and new understandings of the outburst mechanism in recent years. Firstly, controlling factors of coal and gas outburst are classified for an in-depth analysis of the main factors of the same type of disasters, and the research progress and new understandings of the mechanism of coal and gas outburst are systematically sorted out. Secondly, the influencing factors of the strength coal mass are analyzed, and the related issues of coal mass strength on coal and gas outburst disaster mechanism are discussed. The results show that the stages of incubation, occurrence, development, and stop on coal and gas outburst are affected by the coupling effects of in situ stress field, gas pressure field, and seepage field, and the coal strength becomes an important factor affecting outburst strength under the same in situ stress and gas pressure. Therefore, the scientific and reasonable improvement methods of such similar simulation experiment devices are proposed according to the existing experimental methods and devices, which is of great significance to provide ideas for the continuous transferring to deep mining and preventing coal and gas outburst in China in the future.

Fractal Pore and Its Impact on Gas Adsorption Capacity of Outburst Coal: Geological Significance to Coalbed Gas Occurrence and Outburst

“…Coalbed methane is a serious safety hazard in coal mines [1,2], while it is also an important economical natural gas supply [3,4]. The mechanism of gas occurrence, emission, and outburst is not only controlled by macroscopic geological factors [5,6] but also closely correlated to the microscopic structure in coal reservoirs [7,8]. The effects of geological factors on gas occurrence and outburst have been studied extensively [9][10][11].…”

Study on the Precursor Characteristics of Instability Failure of Gas-Bearing Coal Based on Stress and Gas Seepage Volume

“…China is currently the world's largest coal producer and consumer, with coal consumption accounting for 56.0 per cent of total energy in 2018 [1], and China's coalbed methane resources ranked third globally [2]. Most of the mines that experienced disasters associated with rockburst and gas were high gas mines, in which rockburst created conditions for a large number of rapid gas emissions, and high gas pressure also constituted the dynamic conditions for rockburst [3][4][5]. With the gradual increase of coal mining depth, the gas pressure, gas content, and ground stress of coal seam were increasing; the gas permeability was gradually decreasing, in which the deep coal seam with high gas content gradually transformed into the outburst coal seam; and the coal-gas dynamic disaster was becoming more and more serious [6,7].…”

Discussion on the Main Control Effect of Geological Structures on Coal and Gas Outburst

“…Wang proved through experiments that the change in gas release intensity caused by the change in the in situ stress is essential in inducing coal and gas outbursts . Furthermore, air pressure can change the mechanical properties of coal, which leads to higher air pressure, greater released energy, , and higher outburst intensity. Jia combined the characteristics of coal and gas outbursts in this area, discussed the influence of structural stress fields on the geological structure distribution, gas storage, and structural coal development, and further studied the influence of structural stress fields on coal and gas outbursts.…”