Research on a Numerical Simulation and Prediction Model of Floor Mining Failure Depth in the Chenghe Mining Area

Table 1

List of rock mass parameters.

Lithology	Thickness (m)	Cumulative thickness (m)	Bulk modulus (GPa)	Shear modulus (GPa)	Density (kg·m^-3)	Cohesion (MPa)	Internal friction angle (°)	Tensile strength (MPa)
Overlying rock	28	28	4.67	4.34	2670	4.67	39	1.34
Sandy mudstone	8	36	3.65	3.28	2640	2.25	38	1.55
Medium-grained sandstone	6	42	3.38	3.32	2650	5.00	40	1.10
Sandstone	6	48	4.22	4.03	2620	3.98	39	1.11
Sandy mudstone	2	50	3.65	3.28	2640	2.25	38	1.55
No. 5 coal seam	4	54	1.43	0.44	1400	1.52	28	0.10
Quartz sandstone	3	57	4.54	4.31	2660	4.72	40	1.21
Interbedding of sandy mudstone and quartz sandstone	7	64	4.20	4.15	2640	4.58	39	1.24
No. 6 coal seam and sandy mudstone interbeds	2	66	3.65	3.28	2640	2.25	38	1.55
Medium-grained sandstone	4	70	3.38	3.32	2650	5.00	40	1.10
K2 limestone	4	74	22.6	11.1	2090	3.65	37	1.71
No. 10 coal seam	2	76	1.43	0.44	1400	1.00	25	0.10
Aluminous mudstone	6	82	4.86	4.78	2620	4.71	30	1.51
Ordovician limestone	8	90	8.78	5.23	2770	4.32	37	1.32