Influence of Coal Caving Time and Tail Beam Swing Angle on the Evolution of the Coal Gangue Boundary Line during Top Coal Caving

Figure 6

Comparison curve of the coal gangue boundary at different angles. (a) The boundary curve at 3 s. (b) The boundary curve at 5 s. (c) The boundary curve at 7 s. (d) The boundary curve at 9 s.

(a)

(b)

(c)

(d)