Analysis of Stability Factors of Roadway Roof and Determination of Unsupported Roof Distance

Table 3

Distribution of 8^# coal and roof and floor strata.

No.	Lithology	Thickness (m)	Lithology description
5	Fine sandstone	7.74	Gray, grayish white, mainly composed of quartz, containing dark minerals and muscovite fragments and argillaceous siliceous cementation
4	Sandy mudstone	1.15	Gray, dense, brittle, flat section, containing more phytochemical fragments
3	8 coal	3.54	It is mainly powdery, belonging to semidark and semibright briquette, and some contain coal gangue and carbonaceous shale
2	Mudstone	3.01	Gray-dark gray, dense, brittle, rich in rooted fossils
1	Siltstone	4.35	Gray-light gray, dense, brittle, containing plant fossils and vein bedding, with siderite sandstone at the bottom