Fig 1.
Characteristics of bedding and joints of coal.
Fig 2.
Coal sample preparation (a) Core direction (b) Coal sample (c) The coal form after multi-direction sample.
Fig 3.
Mechanical testing (a) Compression test (b) Tensile test.
Fig 4.
Load-deformation curve of uniaxial compressive strength test.
Fig 5.
Load-deformation curve of uniaxial tensile strength test.
Table 1.
Test results of compressive and tensile strength.
Fig 6.
Calculation model of blasting crack.
Table 2.
The effective distances of the crushing and crack zones.
Fig 7.
The crushing and crack distances of blasting (a) The crushing and crack distances in different direction (b) The crushing and crack zones.
Fig 8.
Hole layout for blasting effect investigation.
Fig 9.
Curve diagrams of gas drainage concentration and pure methane quantity (a) No.2 gas drainage hole (b) No.2’ gas drainage hole.
Fig 10.
Ratio after and before blasting with the different distances between gas drainage hole and blasthole (a) Methane concentration (b) Pure methane quantity.
Table 3.
The measurements of blasting cracking effect.
Fig 11.
Blasting crushing-crack distance of coal seam.
Fig 12.
Simplified blasthole layout schematic diagram.
Fig 13.
Blasthole layout for a mining panel (a) Design of in this paper (b) Conventional design.
Table 4.
The layout way of parameter.
Fig 14.
The effect of gas drainage before and after blasting with the two methods (a) The methane concentration (b) Gas drainage quantity.