The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

306 / 2018-05-03 10:44:51

Experimental research on occurrence laws and mechanism of gassy coal extrusion

Gassy coal extrusion,Occurrence laws,Occurrence mechanism,Simulation experiment

Gas of Coal Mine & Coal and Gas Outburst > Coal and gas outburst

Coal, rock and gas dynamic disasters are the major threats in the mining of highly gassy coalmine. During shallow mining, stress is small and the main disaster is coal and gas outburst. With the increasing of mining depth, the influence of stress on coal and gas dynamic disaster is becoming increasingly apparent. Gassy coal extrusion that has characteristics different from coal and gas outburst occurs more and more frequent. To study on the occurrence laws and mechanism of gassy coal extrusion, an analogous test device was developed to simulate gassy coal extrusion under different conditions, and a series of experiments were conducted. The results show that gassy coal extrusion develops gradually from shallow to deep coals and is accompanied by stress transferring, coal fracturing, and sequential gas pressure releasing. The developing process of gassy coal extrusion can be divided into rapid stripping stage and slow fracturing stage. During the rapid stripping stage, gas pressure and stress decrease rapidly, and the coal is stripped and broken into fragments. During the slow fracturing stage, gas pressure is slowly released, and stress shows a trend of decreasing after increasing, and the coal fractures slowly, forming an arc layered fracture. The causes of coal failure in the process of coal extrusion include the gradual unloading of radial support force in the direction of extrusion, releasing of gas pressure and transferring of stressed. The occurrence of gassy coal extrusion takes a long time and has weak dynamic effect.