Table 2 PPV thresholds of rock blasting damage under different mineral composition conditions.
From: Cumulative damage characteristics of tunnel initial support concrete under blasting load
Types of rocks | σc /MPa | RQD/% | PPV/cm·s-1 | ||
|---|---|---|---|---|---|
Minor injury area | Moderate damage area | Serious injuries | |||
Soft gneiss | 14 ~ 30 | 20 | 13 ~ 15.5 | 15.5 ~ 35.5 | >35.5 |
Hard gneiss | 49 | 50 | 23 ~ 35 | 35 ~ 60 | > 60 |
Shultze granite | 30 ~ 55 | 40 | 31 ~ 47 | 47 ~ 170 | > 170 |
Phenocryst granite | 30 ~ 85 | 40 | 44 ~ 77.5 | 775 ~ 1240 | > 1240 |
