Coal spontaneous combustion and gas coupling disasters
are the
highest percentage of serious accidents in coal mines, causing the
most serious disasters. China is one of the countries with the most
serious coal spontaneous combustion and gas coupling disasters in
goaf, and it is of great significance to explore the evolution law
of coal spontaneous combustion and gas coupling disasters in goaf
for disaster prevention and control. To study the three-dimensional
spatial characteristics of the hazardous area of the coupling coal
spontaneous combustion and gas disaster in goaf, a discrete element
method-computational fluid dynamics (DEM-CFD)-based hazardous area
reconstruction method was proposed. Taking a fully mechanized caving
face of a coal mine in Shandong, China, as an example, first, the
working face mining model was established by PFC3D, and
the porosity of different horizontal and vertical positions of goaf
after mining was extracted. Second, the porosity extracted was imported
into computational fluid simulation software FLUENT by UDF. Finally,
the distribution laws of oxygen and gas concentration during the real
goaf mining process were simulated and analyzed. The results showed
that the oxygen concentration in the intake roadway at a depth of
50.7 m in goaf decreased to 12%, and the gas concentration at a depth
of 42.0 m in goaf increased to 16%. The oxygen concentration in the
return airway roadway was reduced to 12% at 17.3 m depth in goaf,
and the gas concentration increased to 16% at 6 m in the direction
of goaf. The gas concentration was higher at the return air corner.
The three-dimensional shapes of the hazardous area in goaf were constructed
to satisfy the coupling of O2 concentration field, CH4 explosion limit concentration field, and fracture field and
so were the laws of hazardous area analyzed qualitatively and quantitatively.
It has important research significance for the rapid identification
and determination of the coal spontaneous combustion and gas coupling
disasters hazardous area.