Evolution Law of Coal Seam Abutment Pressure under the Influence of Shallow Buried Complex Strata: A Case Study

Table 3

Material ratio of the model rock layer.

Lithology	Thickness of protolith (m)	Model delamination thickness (mm)	Matching number	Bulk density (g/cm^3)	Weight (kg)	Material consumption per layer (kg)
						Sand	Calcium carbonate	Gypsum	Water
Aeolian sand	3.78	19	05 : 01	1.08	10.15	10.15	Sawdust 1.54	1.05
Conglomerate	40.26	200	7 : 5 : 5	1.6	182.2	159.4	11.4	11.39	18.2
Sandy mudstone	12.50	63	8 : 6 : 4	1.5	46.8	41.6	3.1	2.08	4.7
Medium grained sandstone	22.03	110	7 : 7 : 3	1.6	87.1	76.2	7.6	3.27	8.7
Mudstone	5.12	26	8 : 6 : 4	1.5	12.6	11.2	0.84	0.56	1.3
Sandy mudstone	3.47	18	8 : 6 : 4	1.5	5.2	4.6	0.35	0.23	0.52
Fine grained sandstone	14.48	72	7 : 8 : 2	1.6	23	20.1	2.3	0.57	2.3
Mudstone	8.5	42	8 : 6 : 4	1.5	6.7	6	0.45	0.3	0.67
Sandy mudstone	4.55	23	8 : 6 : 4	1.5	6.7	6	0.45	0.3	0.67
2-2 coal	5.5	28	8 : 6 : 4	1.35	17.4	15	1.16	0.77	1.74
Sandy mudstone	4.03	20	8 : 6 : 4	1.5	5.2	4.6	0.35	0.23	0.52
Fine grained sandstone	8.15	41	7 : 8 : 2	1.6	33.3	29.1	3.32	0.84	3.3
All	132.37	662			517.96	456.35	38	23.6	52