Research Article
Risk Assessment of an Existing Metro Tunnel in Close Proximity to New Shield Tunnels following Construction
Table 7
Classification of structural cracking.
| Impact degree | Maximum width of cracks (mm) | Safety status of existing tunnel structures |
| I | > 0.4 | Unsafe | II | 0.2 < ≤ 0.4 | Relatively unsafe | III | 0.1 < ≤ 0.2 | Relatively safe | IV | ≤ 0.1 | Safe |
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