Research Article
Gob-Side Entry Retaining Technology with Advanced Empty Hole Butterfly-Shaped Weakening in Three-Soft Coal Seam in China
Table 1
Physical and mechanical parameters of rock mass.
| Lithology | Bulk weight (kN/m3) | Compressive strength (MPa) | Tensile strength (MPa) | Elastic modulus (MPa) | Cohesion (MPa) | Internal friction angle (°) | Poisson’s ratio |
| Siltstone | 26.7 | 39.3 | 3.12 | 3.0 × 104 | 6.5 | 33 | 0.22 | Argillaceous siltstone | 26.6 | 34.8 | 3.72 | 3.1 × 104 | 5.7 | 38 | 0.16 | No. 3 coal seam | 13.8 | 7.9 | 0.39 | 0.5 × 104 | 1. 7 | 31 | 0.24 | Siltstone | 26.1 | 21.0 | 1.15 | 1.4 × 104 | 3.5 | 35 | 0.20 | Next slice of no. 3 coal seam | 13.6 | 7.5 | 0.31 | 0.5 × 104 | 1.6 | 31 | 0.23 | Siltstone | 24.9 | 30.3 | 2.65 | 3.4 × 104 | 3.6 | 30 | 0.22 |
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