Research Article
Instability Process of Crack Propagation and Tunnel Failure Affected by Cross-Sectional Geometry of an Underground Tunnel
Table 4
The depth and total length of cracks during tunnel excavation, loading, and stabilization.
| | Initial stress | The occurrence of cracks during excavation | The occurrence of cracks during loading and stabilization |
| | T1 | 4.94 MPa | Excavation depth (mm) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | Stress (MPa) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | | 100 | — | — | — | — | 5.4 | 57.6 | 600.3 | 52 | 569.7 | | 200 | — | — | — | — | 5.52 | 69.2 | 731.8 | 67 | 711 | | 300 | 24 | 206 | 28.1 | 181 | 6.06 | 91 | 932.1 | 83 | 950.9 | | 400 | 42.7 | 469.5 | 41 | 448.5 | 6.3 | 92 | 980.8 | 97 | 1011 |
| | T2 | 4.94 MPa | Excavation depth (mm) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | Load (MPa) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | | 100 | — | — | — | — | 5.43 | 13.4 | 168.9 | 15.5 | 232.1 | | 200 | — | — | — | — | 5.50 | 18.2 | 211.7 | 22.9 | 300.9 | | 300 | — | — | — | — | 5.56 | 24.5 | 298.3 | 23.7 | 346.5 | | 400 | 3.4 | 43.8 | 7.2 | 58.8 | 5.84 | 39.5 | 550.4 | 44.3 | 616.4 |
| | T3 | 5.63 MPa | Excavation depth (mm) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | Time of stabilization (min) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | | 100 | — | — | — | — | 8 | 65.6 | 633.3 | 63 | 660 | | 200 | — | — | — | — | 18 | 74.7 | 685.5 | 78 | 810.7 | | 300 | 28.5 | 192 | 20.9 | 202.7 | | | | | | | 400 | 64.7 | 590.2 | 58.5 | 621.6 | | | | | |
| | T4 | 5.36 MPa | Excavation depth (mm) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | Time of stabilization (min) | Left depth (mm) | Left length (mm) | Right depth (mm) | Right length (mm) | | 100 | — | — | — | — | 4 | 39.31 | 351.6 | 44.76 | 252.3 | | 200 | — | — | — | — | 23 | 40.67 | 467.0 | 44.76 | 347.2 | | 300 | 10.2 | 41.3 | 9.5 | 40.9 | 240 | 40.67 | 501.6 | 44.76 | 390.0 | | 400 | 23.6 | 178.2 | 23.5 | 168.8 | | | | | |
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