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

Figure 3

Coal samples. (a) No. 1 coal sample. (b) No. 2 coal sample. (c) No. 3 coal sample. (d) No. 4 coal sample. (e) No. 5 coal sample. (f) No. 6 coal sample. (g) No. 7 coal sample.

(a)

(b)

(c)

(d)

(e)

(f)

(g)