Research Article
Small Pilot Tunnel Advance and Step Reverse Expansion in Super-Large-Section Tunnel Excavation
Table 2
Maximum settlement value of each key construction sequence.
| | Key construction steps | Maximum settlement value (mm) | Percentage of settlement value (%) | Accumulated percentage of settlement value (%) |
| | Excavation of the left pilot tunnel | 2.34 | 45.2 | 45.2 | | Excavation of the upstairs | 4.64 | 44.4 | 89.6 | | Excavation of the middle stairs | 4.91 | 5.2 | 94.8 | | Invert excavation | 5.02 | 2.1 | 96.9 | | Second lining | 5.18 | 3.1 | 100 |
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