Q=qSLη
Where: S—well section size, m 2 ;
L—average blasthole depth, m;
η—The utilization of the blasthole is generally 80% to 95%.
q—Unit explosive consumption
 Explosive consumption of tunneling unit ( kg·m - 3 ) 　　　　　　　　
Excavation sectional area / m 2 | Rock's firmness coefficient | ||||
2~3 | 4~6 | 8~10 | 12~14 | 15~20 | |
<4 4~6 6~8 8~10 10~12 12~15 15~20 >20 | 1.23 1.05 0.89 0.78 0.72 0.66 0.64 0.60 | 1.77 1.50 1.28 1.12 1.01 0.92 0.90 0.86 | 2.48 2.15 1.89 1.69 1.51 1.36 1.31 1.26 | 2.96 2.64 2.33 2.04 1.90 1.78 1.67 1.62 | 3.36 2.93 2.59 2.32 2.10 1.97 1.85 1.80 |
After obtaining the total circulating dose, the dosage is distributed according to the action and conditions of each blasthole in the blasting. Among them, the sulcus is the most important, and the blasting conditions are the worst. More doses should be allocated. The amount of auxiliary eye drops is second, and the distribution of peripheral eye drops is the least.
The determination of the number of blastholes is mainly related to the roadway section, rock properties, explosive properties and other factors. Generally, the number of eyes is reduced as much as possible while ensuring a reasonable blasting effect.
The depth of the blasthole is related to the area of ​​the tunneling section, the degree of mechanization of the tunneling and the level of blasting technology. Under the existing conditions, the depth of the blasthole of the monorail canopy is between 1.5 and 2.5 m.
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