Research Article
A Rock Mass Classification Method for Tuff Tunnel Based on the High-Pressure Gas Expansion Method
Table 4
Tunnel rock mass classification for HPGEM.
| Rock mass grades | (MPa) | | Quantitative indices (BQ value) |
| | 150∼100 | 0.86∼0.7 | 637.2∼554 | | 100∼60 | 0.7∼0.55 | 554∼417.5 | | 60∼30 | 0.55∼0.4 | 417.5∼290 | | ≥150 | ≥0.86 | ≥637.2 | | ≤30 | ≤0.4 | ≤290 |
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