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

Table 1

Proportion of the materials in each rock stratum of the similar physical model.

Rock stratum		Material ratio (sand: calcium carbonate: gypsum)	Actual rock thickness (m)	Similar physical model thickness (cm)
	Sandy soil	6 : 7 : 3	17.04	7.10
	Medium- to coarse-grained dolomite	4 : 2 : 8	104.00	43.33
	Bedded argillaceous dolomite	4 : 5 : 5	9.00	3.75
	Quartz sandstone	3.8 : 5 : 5	17.80	7.42
	Phosphate ore	3 : 2 : 8	13.30	5.54
	Low-grade phosphorus ore	3.2 : 3 : 7	16.87	7.03
	Boundary ore	3.8 : 4 : 6	5.06	2.11
	Light grey primary dolomite	3.5 : 3 : 7	16.00	6.67
	Deep grey medium-thick layered primary dolomite	3.5 : 3.5 : 6.5	33.50	13.96