Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

Figure 4

Nephograms of deviatoric stress after mining of N8707 and N8709 coal faces in No. 7-4 coal seam: (a) nephogram of deviatoric stress after mining of the N8707 coal face in No. 7-4 coal seam; (b) nephogram of deviatoric stress after mining of the N8709 coal face in No. 7-4 coal seam.

(a)

(b)