Study on Stability of Stope Surrounding Rock under Repeated Mining in Close-Distance Coal Seams

Table 2

Model of similar material ratio of rock strata.

Lithology	Model thickness/(cm)	Layer number	Layer thickness/(cm)	Ratio	Sand (kg)	Lime (kg)	Gypsum (kg)
Fine sandstone sandstone	8.00	2	4	655	8.49	0.71	0.71
Silty mudstone	20.00	4	5	755	8.67	0.66	0.66
Mudstone	20.00	5	4	764	8.67	0.75	0.5
15# coal seam	6.00	1	6	855	8.81	0.55	0.55
Sandy mudstone	10.00	2	5	764	8.67	0.75	0.5
Fine sandstone	20.00	5	4	655	8.49	0.71	0.71
16# coal seam	8.00	1	8	855	8.81	0.55	0.55
Siltstone	25.00	5	5	664	8.49	0.85	0.56
Fine sandstone	15.00	5	3	655	8.49	0.71	0.71
17# coal seam	18.00	1	18	855	8.81	0.55	0.55