Table 1 PPV thresholds for rock blasting damage.
From: Cumulative damage characteristics of tunnel initial support concrete under blasting load
PPV/cm·s-1 | Effects of rock mass damage |
|---|---|
< 25 | Intact rock will not fracture |
25  ~ 63.5 | The rock mass will undergo slight tensile cracking |
63.5 ~ 254 | Severe tensile cracks and radial cracks |
> 254 | The rock mass is completely broken |
