Research Article
Study on Identification of Construction Method for Ultra-Large-Span Tunnel
Table 5
Criterion and quantitative standard of surrounding rock stability state.
| No. | Conditions of the plastic zone | Stability of surrounding rock | Quantitative score |
| 1 | Communicated plastic zones occur in both joint planes and rock blocks | Unstable | 1 | 2 | Plastic zones occur in both joint planes and rock blocks, but only communicate in joint planes | Unstable | 2 | 3 | Communicated plastic zones only occur in joint planes | Unstable | 3 | 4 | Noncommunicated plastic zones occur in both joint planes and rock blocks | Stable | 4 | 5 | Noncommunicated plastic zones occur in joint planes | Stable | 5 | 6 | No plastic zones occur in both joint planes and rock blocks | Stable | 6 |
|
|