Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers

Table 5

Experimental model ratio.

Lithology	Thickness (cm)	Matching number (sand : lime : plaster)	Sand (kg)	Lime (kg)	Plaster (kg)	Water (kg)
Sandy mudstone	16.5	9 : 0.5 : 0.5	200.48	11.14	11.14	22.75
Siltstone	8.0	8 : 0.6 : 0.4	96.0	7.2	4.8	10.8
Mudstone	0.5	8 : 0.6 : 0.4	6.0	0.45	0.3	0.7
Quartz sandstone	7.6	7 : 0.5 : 0.5	89.8	6.4	6.4	10.3
9-2# coal	0.9	8 : 0.7 : 0.3	10.8	0.95	0.41	1.2
Mudstone	1.8	8 : 0.6 : 0.4	21.6	1.62	1.08	2.4
9-1# coal	1.9	8 : 0.7 : 0.3	22.8	2.0	0.86	2.6
Mudstone	2.5	8 : 0.6 : 0.4	30.0	2.25	1.5	3.4
Siltstone	5.2	8 : 0.6 : 0.4	62.4	4.68	3.12	7.0
Sandy mudstone	1.3	9 : 0.5 : 0.5	15.8	0.88	0.88	1.8
8# coal	3.6	8 : 0.7 : 0.3	43.2	3.78	1.62	4.9