Burst Failure Characteristics and Energy Evolution Law of Coal with Prefabricated Cracks at Different Angles

Figure 11

Coal fracture propagation under different crack angles: (a) 0° crack; (b) 15° crack; (c) 30° crack; (d) 45° crack; (e) 60° crack; (f) 75° crack; (g) 90° crack.

(a)

(b)

(c)

(d)

(e)

(f)

(g)