Fig 1.
Air leakage from surface mining fractures in the 6104 working face.
Fig 2.
Layout of the SF6 release points and collection points.
Table 1.
Air leakage test analysis.
Fig 3.
Distribution of the surface air leakage speed contours.
Fig 4.
Predicted air leakage speeds at the working face of 6104.
Fig 5.
Porosity distribution in goaf.
Fig 6.
Numerical calculation model of goaf.
(a) Physical model face; (b) Meshing.
Fig 7.
Distribution of the pressure, air leakage velocity and air leakage flow field in goaf.
(a) relative pressure; (b) air leakage speed; (c) air leakage flow field.
Fig 8.
Distribution of oxygen concentration in the goaf.
Fig 9.
Layout of measuring points of pre-embedded beam tube in working face.
Fig 10.
Distribution of O2 and CO at different locations in the goaf.
Fig 11.
Distribution of pressure and air leakage flow field in goaf under different pressure differences between the ground surface and mining face.
(a) ΔP = 800 Pa; (b) ΔP = 600 Pa; (c) ΔP = 400 Pa; (d) ΔP = 200Pa; (e) ΔP = 0 Pa; (f) ΔP = -200 Pa.
Fig 12.
"Three zones" of spontaneous combustion in the goaf under different pressure differences between the mining face and ground surface.
Fig 13.
Air leakage of the working face and upper corner CO concentration during pressurization.
Fig 14.
Prediction of air leakage in the 6104 working face.