Study on the Evolution Characteristics of Two-Zone Failure Mode of the Overburden Strata under Shallow Buried Thick Seam Mining

Figure 3

The evolution process of “two zone.” (a) 60 m. (b) 90 m. (c) 135 m. (d) 135 m, after 10 minutes. (e) 50 m. (f) 165 m. (g) 180 m

(a)

(b)

(c)

(d)

(e)

(f)

(g)