Effect of Mining Thickness on Overburden Movement and Underground Pressure Characteristics for Extrathick Coal Seam by Sublevel Caving with High Bottom Cutting Height

Table 6

Rock pillar height which needs to be controlled under different conditions of main roof movement in different thick coal seams.

State of the roof	Actual height of rock pillar should be controlled (m)
	9 m	15 m	25 m
Normal circumstance	18.47∼27.12	24.27∼39.73	31.63∼50.22
Lower main roof pressure	35.40∼39.08	51.23∼59.69	52.24∼68.89
Higher main roof pressure	50.22∼50.68	68.34∼71.75	82.51∼93.64