Research Article
Failure Mechanism and Control of Lower Retracement Channel in Close-Distance Double-Thick Coal Seams
Table 3
Coal pillar safety factor.
| Safety factor (FOS) | 0 ≤ FOS < 0.8 | 0.8 ≤ FOS ≤ 1 | 1 < FOS ≤ 1.5 | FOS ≥ 2 |
| Coal pillar state | Unstable | Critical stable | Stable | Absolute stable |
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