Energy Accumulation and Dissipation of Coal with Preopening under Uniaxial Loading

Figure 21

Macrofracture morphology of coal sample with different hole number. (a) Intercoal specimen, (b) N = 1, (c) N = 2, (d) N = 3, and (e) N = 4.

(a)

(b)

(c)

(d)

(e)