Similar Physical Modeling of Roof Stress and Subsidence in Room and Pillar Mining of a Gently Inclined Medium-Thick Phosphate Rock

Table 2

Materials used in the rock strata of the similar physical model.

Rock stratum	Sand (kg)	Calcium carbonate (kg)	Gypsum (kg)	Water (kg)	Borax (kg)
Sandy soil	88.73	10.35	4.44	11.50	115.00
Medium- to coarse-grained dolomite	505.40	25.27	101.09	70.19	701.90
Bedded argillaceous dolomite	43.74	5.47	5.47	6.07	60.70
Gravel quartzite	85.64	11.27	11.27	12.02	120.20
Phosphate ore	60.58	4.04	16.16	8.97	89.70
Low-grade phosphorus ore	78.10	7.32	17.08	11.39	113.90
Boundary ore	24.35	2.56	3.85	3.42	34.20
Light grey primary dolomite	75.64	6.48	15.13	10.81	108.10
Deep grey medium-thick layered primary dolomite	158.31	15.83	29.40	22.62	226.20