The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra-Thick Coal Seams: A Typical Case Study

Figure 12

Structure failure process of key stratum in different cycles. (a) Cycle 10000. (b) Cycle 50000. (c) Cycle 80000. (d) Cycle 120000.

(a)

(b)

(c)

(d)