Calculation Method of Overburden Damage Height Based on Fracture Mechanics Analysis of Soft and Hard Rock Layers

Table 5

Fracture numbers with different borehole depths before and after mining.

Different borehole depth range (m)	Fracture number (bars)
	Before mining	After mining
0~10	0	2
10~20	6	21
20~30	9	32
30~40	6	38
40~50	4	33
50~60	5	21
60~70	4	9
70~80	1	6