Research on the Reasonable Width of the Waterproof Coal Pillar during the Mining of a Shallow Coal Seam Located Close to a Reservoir

Figure 6

Roof caving when the working face advances to 58 cm (a), 99 cm (b), 128 cm (c), 139 cm (d), 155 cm (e), 221 cm (f), and 246 cm (g), respectively.

(a)

(b)

(c)

(d)

(e)

(f)

(g)