Evolution Law of Overburden Longitudinal Connected Fissures in a Shallowly Buried Coal Face with Thin Bedrock

Figure 5

Entire opening and closing process of a longitudinal connected fissure in bedrock. (a) Fissure begins to open. (b) Fissure at its maximum extent. (c) Fissure closes quickly. (d) Fissure closes completely.

(a)

(b)

(c)

(d)