A Rock Mass Classification Method for Tuff Tunnel Based on the High-Pressure Gas Expansion Method

Table 1

Rock mass integrity index and rock volume nodule number .

(strip/)
<3	>0.75
3∼10	0.75∼0.55
10∼20	0.55∼0.35
20∼35	0.35∼0.15
≥35	≤0.15