Reasonable Scope of Kilometer Drilling in Lower Layer of Extrathick Coal Seam: A Case Study of Tingnan Coal Mine, China

Figure 12

Figure of plastic zone under different depths of working face. (a) 1 m under the floor. (b) 3 m under the floor. (c) 6 m under the floor. (d) 9 m under the floor. (e) 12 m under the floor. (f) 14 m under the floor. Legend: none: no shear failure occurred in the unit; shear-p: shear failure occurred in the element; shear-n: the unit is generating shear failure; tension-p: units were damaged by tension; tension-n: the unit is undergoing tensile damage.

(a)

(b)

(c)

(d)

(e)

(f)