Research Article
Gob-Side Entry Retaining Technology with Advanced Empty Hole Butterfly-Shaped Weakening in Three-Soft Coal Seam in China
Figure 20
Change curve of the observed roof to floor convergence: (a) No. 1 measurement point; (b) No. 2 measurement point; (c) No. 3 measurement point; (d) No. 4 measurement point; (e) No. 5 measurement point; (f) No. 6 measurement point.
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