The Static Breaking Technique for Sustainable and Eco-Environmental Coal Mining

Figure 5

The expansion status of the first occurring cracks A and B.

(a) 𝑡=0 min

(b) 𝑡=15 min

(c) 𝑡=20 min

(d) 𝑡=30 min

(e) 𝑡=40 min

(f) 𝑡=50 min

(g) 𝑡=60 min

(h) 𝑡=80 min