Study on the Upper Limit of Roof Failure in Soft Rock Roadway

Table 2

Physical and mechanical parameters and ratio number of each rock stratum.

Strata sequence	Lithologic characters	Thickness (m)	The thickness of the model (cm)	Proportion number sand : gypsum : calcium carbonate	Sand quality (kg)	Gypsum quality (kg)	Calcium carbonate (kg)
1	Siltstone	1.00	10.0	8 : 3 : 7	11.94	0.45	1.05
2	Oil shale	5.95	59.5	8 : 3 : 8	11.62	0.42	1.20
3	Siltstone	1.28	12.8	8 : 3 : 7	11.94	0.45	1.05
4	5 #coal	2.12	21.2	(Coal) 20 : 20 : 1 : 5	0.14	0.73	2.94
5	Mudstone	2.00	20.0	8 : 2 : 8	11.94	0.45	1.05