Characteristics of Coal and Gas Outburst within Gas Geological Units in Qidong Mine
The precise mechanism of the coal and gas outburst is still unresolved, but productive practices in Qidong mine have testified that the coal and gas outburst accidents are predominantly associated with the belt of geological structure, the zone of tectonic coal occurrence and the area of the stress concentration. So it is very important to study characteristics of coal bed gas geology for coal bed gas prediction and prevention. Using gas-geology theory and method, the research focused on the factors of coal and gas outburst, such as coal bed gas occurrence, stress distribution, tectonic coal occurrence and magmatic rock presence within Qidong mine. The result shows that: Qidong mine district could be divided into 4 geological units by 3 faults as the boundary, the faults of Weimiao fault, F 2 , and F 5 ; there are different conditions and main controlling factors of coal bed gas occurrence within four geological units. The unit I of geology: coal bed gas occurrence conditions are simpler, mainly contacted with the coal burial depth; the unit II: the conditions are more complex, predominantly associated with fault structures; the unit III: as a result of the presence of igneous intrusions, coal bed gas content in unit III is the highest within the whole mine; the unit IV: major factor of the conditions is the fold caused by strata uplift, which also leads to a large number of gas emissions. 25 coal and gas outburst accidents all occurred within the unit II of geology.