Research Article
Stability Analysis and Fracture Patterns of Hard Main Roof in Longwall Top Coal Caving with Large Mining Height
Table 4
Ultimate fracture span of key stratum in No. 8100 longwall face.
| Seam no. | Lithology of key stratum | Position of key stratum | Ultimate fracture span | Distance from the coal seam (m) | Cantilever beam | Voussoir beam |
| 17 | Glutenite | Upper key strata | 91.4 | 91.4–109.7 | 338.0 | 16 | Fine-grained sandstone | | 90.0 | 90.0–108.0 | 258.0 | 12 | Fine-grained sandstone | | 55.1 | 55.1–66.1 | 118.0 | 8 | Fine-grained sandstone | | 37.2 | 37.2–44.6 | 58.0 | 4 | Fine-grained sandstone | Lower key strata | 33.1 | 33.1–39.7 | 18.0 | 2 | Medium conglomerate | | 24.7 | 24.7–29.6 | 4.0 |
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