Investigation of the Optimal Layout of the Roadway in Closely Spaced Ultra-Thick Coal Seams Mining with Remaining Coal Pillars

Figure 3

Drilling peep results of 30503 repaired roadway roof. (a) Cracks at 2.9 m in no. 01 borehole. (b) Cracks at 3.4 m in no. 02 borehole. (c) Cracks at 5.4 m in no. 03 borehole. (d) Cracks at 1.5 m in no. 04 borehole. (f) Cracks at 2.5 m in no. 04 borehole. (e) Cracks at 6.5 m in no. 05 borehole.

(a)

(b)

(c)

(d)

(e)

(f)