Similar Material Simulation Study on Protection Effect of Steeply Inclined Upper Protective Layer Mining with Varying Interlayer Distances

Table 4

Proportioning parameters and mechanical parameters of similar materials for each stratum.

Stratum number	Lithology	Density (kg·m^−3)	Sand-binder ratio	Elastic modulus (MPa)	Compressive strength (MPa)
			Sand : cement
1	Limestone	1.656	6 : 1	178.61	0.63
2	Allitic shale	1.637	6 : 1	162.31	0.63
3	C6 coal seam	1.513	9 : 1	10.19	0.04
4	Composite medium stratum	1.551	6.5 : 1	140.80	0.70
5	C4 coal seam	1.513	9 : 1	10.09	0.04
6	Siltstone	1.539	7 : 1	110.81	0.54
7	Limestone	1.656	6 : 1	178.61	0.63