Research Article
Study on Roof-Coal Caving Characteristics with Complicated Structure by Fully Mechanized Caving Mining
Table 3
Mechanical parameters of contact surface between hard seam and coal seam in different layers of top coal.
| | Rock stratum | Normal stiffness, jkn (GPa) | Shear stiffness, jks (GPa) | Internal friction angle, f (°) | Cohesive force, C (MPa) | Tensile strength, t (MPa) |
| | Hard coal gangue (hard coal) | 4 | 3.5 | 27 | 0.04 | 0 | | Hard coal gangue (gangue) | 14 | 5 | 29 | 0.05 | 0 | | Top coal | 4 | 3 | 14 | 0.02 | 0 | | Overlying strata | 16 | 6 | 31 | 0.07 | 0 | | Basic roof | 16 | 6 | 31 | 0.07 | 0 | | Immediate roof | 7 | 5 | 0 | 0 | 0 | | False roof | 6 | 4.5 | 0 | 0 | 0 | | Direct bottom | 5 | 6 | 28 | 0.06 | 0 | | Previous bottom | 5 | 6 | 32 | 0.1 | 0 |
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