Dynamic Effect and Control of Key Strata Break of Immediate Roof in Fully Mechanized Mining with Large Mining Height

Table 2

Modelling material ratio.

Lithology	Accumulated height/cm	Model height/cm	Layer volume/cm^3	Sand weight/kg	Gypsum weight/kg	CaCO3 weight/kg	Water weight/kg
Packsand	140	4.5	22500	32.8	3.9	2.2	4.6
Medium sandstone	135.5	5	25000	36.4	3.6	3	5.1
Sandy mudstone	130.5	6	30000	44.6	4.5	2.6	6
Packsand	124.5	4	20000	29.1	3.5	1.9	4.1
Medium sandstone	120.5	2	10000	14.6	1.5	1.2	2
Sandy mudstone	118.5	4	20000	29.8	3	1.7	4
Mudstone	114.5	7.5	37500	55.8	4.8	4	7.5
Coal	107	1	5000	7.4	0.5	0.6	1
Sandy mudstone	106	5.5	27500	40.9	4.1	2.4	5.5
Packsand	100.5	1	5000	7.3	0.9	0.5	1
Mudstone	99.5	10	50000	74.4	6.3	5.3	10
Coal	89.5	1.5	7500	11.2	0.8	1.0	1.5
Sandy mudstone	88	7.5	37500	55.8	5.7	3.2	7.5
Medium sandstone	80.5	5	25000	36.4	3.6	3	5.1
Limestone	75.5	3	15000	21.3	2.6	2.1	3.6
Sandy mudstone	72.5	6.5	32500	48.4	4.9	2.8	6.5
Packsand	66	5.5	27500	40.1	4.8	2.7	5.6
Mudstone	60.5	4.5	22500	33.5	2.9	2.4	4.5
Limestone	56	6	30000	42.5	5.1	4.3	7.3
Coal	50	1	5000	7.4	0.5	0.6	1
Sandy mudstone	49	6	30000	44.6	4.5	2.6	6
Mudstone	43	4.5	22500	33.5	2.9	2.4	4.5
Limestone	38.5	5	25000	35.4	4.3	3.5	6.1
Mudstone	33.5	6	30000	44.6	3.8	3.2	6
Packsand	27.5	2	10000	14.6	1.7	1	2
Sandy mudstone	25.5	3	15000	22.3	2.3	1.3	3
Packsand	22.5	6	30000	43.7	5.2	2.9	6.1
Mudstone	16.5	6	30000	44.6	3.8	3.2	6
15# coal	10.5	5.5	27500	40	4	2.6	5.2
Sandy mudstone	5	5	25000	37.3	3.6	2.5	4.7