1. Audible omen: muffled thunder, firecrackers, machine gun sound, hum, gas anomaly, gas fluctuation, blowhole, airflow reversal, whistle sound and buzzer sound.
2. Silent omen: coal structure bedding disorder, coal blackening, rapid change of coal thickness, soft and dry coal body, coal seam cracking, bedding inversion, coal wall cracking, slag falling, peeling, coal wall protruding, serious deformation of drilling hole, cross-hole, blasting hole unable to hold explosives, temperature drop, coal wall cooling, special smell, etc.
Extended data:
The gas component emitted is usually methane (CH4) and in some cases carbon dioxide. Coal and gas outburst is called coal and gas outburst, and rock and gas outburst is called rock outburst. Coal (rock) and gas outburst damage roadway and equipment, often causing casualties.
The intensity of coal (rock) and gas outburst is usually expressed by primary coal (rock) outburst. /kloc-below 0/00t is a general outburst,/kloc-below 0/00 ~ 500t is a serious outburst, below 500 ~1000t is a big outburst, and above1000t is a very big outburst.
There are three kinds of gas outburst:
1, outburst, produced under the joint action of ground pressure and gas, which participated in the process of coal and rock crushing and migration.
2. Extrusion is mainly caused by ground pressure, with less gas and pulverized coal.
3. Dumping: After the coal and rock are dumped, the included angle between the hole axis and the horizontal plane is greater than 45, and the angle of coal accumulation is close to the angle of repose of the coal pile.
References:
Baidu encyclopedia-gas outburst