Research on the First Breaking Mechanism of the Main Roof of Coal Seam with High Dip Angle
Table 1
Features of coal seam roof and floor.
Roof or floor
Rock type
Thickness (m)
Lithological characteristics
Main roof
White sandstone
Light gray sandstone with medium grains, hard, with vertical fracture, undeveloped joint, compressive strength 84.8 MPa, inclination 29°
Immediate roof
Mudstone
Black mudstone with bright strip, brittle, developed joint, compressive strength 15.8 MPa, inclination 29°
Immediate floor
Mudstone
Grayish black mudstone, dense and massive, mainly composed of argillaceous components, containing a large amount of plant fossil, developed joint, compressive strength 18.5 MPa, inclination 29°
Main floor
Sandstone
Gray white sandstone, mainly composed of quartz, with carbon chips and carbon stripes, undeveloped joint, compressive strength 38 MPa, inclination 29°