Acoustic Emission Experimental Research of the Damage Characteristics of Raw Coal under Different Loading and Unloading Rates

Figure 10

Destruction status of coal samples at different unloading rates. (a) No. 4 coal sample. (b) No. 5 coal sample. (c) No. 6 coal sample. (d) No. 7 coal sample.

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(b)

(c)

(d)