Determination of the Ultimate Underground Mining Depth considering the Effect of Granular Rock and the Range of Surface Caving

Table 2

The basic quality indexes of the southeast mining area in the Gongchangling Iron Mine.

Material	(MPa)	GSI	a	m	mb	s
Hanging wall	55.5	67	0.5	8	2.46	0.026
Foot wall	100	77	0.5	25	11	0.078
Ore body	113.4	82	0.5	24	12.6	0.135