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

<div>Modes of composite structure of lower and upper voussoir beam with hard main roof. (a) Instability of lower voussoir beam. (b) Synchronous instability of lower and upper beams.</div>

Shock and Vibration

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Figure 8

Figure 8: Stability Analysis and Fracture Patterns of Hard Main Roof in Longwall Top Coal Caving with Large Mining Height 