Study on Deformation Mechanism and Supporting Countermeasures of Compound Roofs in Loose and Weak Coal Roadways

Table 1

Coal seam roof and floor properties.

Roof and floor type	Rock type	Thickness (m)	Lithologic features
Pseudotop	Shale, coal	0–1.0	Gray-black, thin layer, coal line
Direct top	Shale	1.5	Black dense shale
Main roof	Siltstone	10.0	Black thin mudstone with thin-layer siltstone
Main floor	Fine sandstone	8.0	Dark gray fine sandstone, thin layer of mudstone black carbonized smooth surface