Rib Spalling 3D Model for Soft Coal Seam Faces with Large Mining Height in Protective Seam Mining: Theoretical and Numerical Analyses

Table 1

The proportions of materials to simulate various lithologies available between the two working faces.

Lithology	Weight proportion
	Fine river sand	Lime	Gypsum	Water
Coal	10	0.5	0.5	1.1
Mudstone	10	0.7	0.3	1.1
Fine sandstone	6	0.6	0.4	0.7
Sandy mudstone	7	0.7	0.3	0.8
Coarse sandstone	8	0.6	0.4	0.9
Siltstone	9	0.5	0.5	1.0