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

Figure 12

Roof failure process: (a) promotion of the second-level recycling route; (b) promotion of the sixth-level recycling route; (c) promotion of the tenth-level recycling route; and (d) promotion of the sixteenth-level recycling route.

(a)

(b)

(c)

(d)