Occurrence Mechanism of Roof-Fall Accidents in Large-Section Coal Seam Roadways and Related Support Design for Bayangaole Coal Mine, China

Figure 8

Detection results of different drilling holes on roof and two sides of monitoring section 1. (a) Observations in drilling hole 1, (b) observations in drilling hole 2, (c) observations in drilling hole 3, and (d) observations in drilling hole 4.

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(b)

(c)

(d)