Behaviors and Overlying Strata Failure Law for Underground Filling of a Gently Inclined Medium-Thick Phosphate Deposit

Figure 11

Roof failure process: (a) promotion of the second-level mining approach; (b) promotion of the sixth-level mining approach; (c) promotion of the tenth-level mining approach; and (d) promotion of the seventeenth-level mining approach.

(a)

(b)

(c)

(d)