Study on the Evolution Law of Fracture Field in Full-Mechanized Caving Mining of Double System and Extrathick Coal Seam

Table 2

Physical and mechanical parameters of coal and rock layers.

Lithology	Thickness (m)	Burial depth (m)	Density (kg/m^3)	Tensile strength (MPa)	Compressive strength (MPa)	Elastic modulus (GPa)	Poisson ratio
Fine-grained sandstone	6.44	346.13	2700	6.4	175.01	44.65	0.124
Siltstone	8.21	354.34	2604	4.89	151.49	37.29	0.164
Sandy mudstone	6.48	372.29	2681	4.4	143.98	38.07	0.291
Medium-grained sandstone	4.3	376.59	2654	5.72	161.96	38.9	0.221
Mudstone	4.2	380.79	2752	2.72	116.01	29.4	0.326
Coarse-grained sandstone	3.64	384.43	2540	2.56	61.76	18.28	0.219
Coarse sandstone with gravel	4.57	492.61	2528	3.2	54.75	15.33	0.232
Coal seams 3–5#	14.05	592.18	1426	4.2	24.8	4.2	0.32