Study on the Evolution Law of Fracture Field in Full-Mechanized Caving Mining of Double System and Extrathick Coal Seam

Table 3

Relationship between advancement detail and the overburden fracture surface.

Fracture type	Advancement (m)	Height (m)	Angle (°)
Fracture surface 1	100	26.9	63
Fracture surface 2	120	61.2	62
Fracture surface 3	160	108.7	67
Fracture surface 4	200	108.7	61
Fracture surface 5	240	123	61
Fracture surface 6	260	123	62
Main fracture surface 7	300	220.9	62
Fracture surface 8	320	123	62
Main fracture surface 9	360	220.9	67