Research Article
Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams
Table 4
Parameters of the indoor physical model.
| Lithology | Thickness (cm) | Compression strength (MPa) | Volume-weight (KN/m3) | Water ratio |
| Unconsolidated formation | 36 | 31.2 | 25 | 1/8 | Main key stratum | 6 | 34.3 | 28 | 1/6 | Immediate roof | 9 | 29.9 | 25 | 1/8 | 1ā2 upper coal seam | 3.5 | 12.0 | 14 | 1/8 | Subcritical strata | 5 | 34.0 | 28 | 1/8 | Immediate roof | 6 | 29.8 | 25 | 1/8 | 1ā2 coal seam | 4.5 | 10 | 14 | 1/8 |
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