Three-Dimensional Physical Simulation and Control Technology of Roof Movement Characteristics in Non-Pillar Gob-Side Entry Retaining by Roof Cutting

Figure 4

Dip excavation of the coal seam. Coal seam excavation: (a) 5 m; (b) 20 m; (c) 45 m; (d) 80 m.

(a)

(b)

(c)

(d)