Research Article
Small Pilot Tunnel Advance and Step Reverse Expansion in Super-Large-Section Tunnel Excavation
Table 1
Tunnel geotechnical properties.
| | Soil category | Layer thickness (m) | Density (kN/m3) | Elastic modulus (kN/m3) | Cohesion (kPa) | Internal friction angle (°) | Poisson’s ratio |
| | Miscellaneous fill | 3.0 | 18.8 | 8 | 20.00 | 16.40 | 0.29 | | Moderately weathered siltstone | 70 | 26.9 | 70 | 9210 | 52.00 | 0.20 | | Slightly weathered siltstone | 50 | 27.9 | 90 | 8000 | 50.50 | 0.20 |
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