Investigation on Surrounding Rock Stability Control Technology of High Stress Roadway in Steeply Dipping Coal Seam

Table 4

Classification of coal roof types.

Classification type	Characteristics of roof types	Thickness between coal seams (m)
I	Broken loose roof	H ≤ 1.5
II	Crack through roof	1.5 < H ≤ 2.5
III	Fractured roof	2.5 < H ≤ 3.5
IV	Partially complete roof	H ＞ 3.5