Stability Analysis and Fracture Patterns of Hard Main Roof in Longwall Top Coal Caving with Large Mining Height

<div>Composite structures of lower cantilever beam and upper voussoir beam with hard main roof. (a) Instability of lower cantilever beam. (b) Synchronous instability of lower and upper structure.</div>

Shock and Vibration

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Figure 7

Figure 7: Stability Analysis and Fracture Patterns of Hard Main Roof in Longwall Top Coal Caving with Large Mining Height 