Experiment on Mine Ground Pressure of Stiff Coal-Pillar Entry Retaining under the Activation Condition of Hard Roof

Figure 5

Roof activation characteristics. (a) Roof bending. (b) Roof fracture. (c) Roof caving. (d) Cantilever construction. (e) Cantilever construction fracture. (f) Cantilever construction caving. (g) Cantilever construction. (h) Cantilever construction fracture. (i) Upper roof condition. (j) Suspended upper roof. (k) Upper roof fracture. (l) Upper roof fracture and caving.

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