Investigation on the Movement and Fracture Characteristics of an Extra-Thick Hard Roof during Longwall Panel Extraction in the Yima Mining Area, China

Table 3

Physical and mechanical parameters of rock strata.

Rock strata	Thickness (m)	Density (kg·m^−3)	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesion (MPa)	Friction angle (°)	Tensile strength (MPa)
Conglomerate	39	2 865	20.33	17.50	11.85	40	10.32
Fine sandstone	2.0	2 873	9.18	8.75	7.51	30	6.65
Conglomerate	3.0	2 865	20.33	17.50	11.85	40	10.32
Fine sandstone	2.0	2 873	9.18	8.75	7.51	30	6.65
Siltstone	2.0	2 707	12.82	10.02	8.97	30	8.65
Mudstone	2.0	2 461	6.11	5.49	4.49	20	4.30
Fine sandstone	1.0	2 873	9.18	8.75	7.51	30	6.65
Mudstone	24	2 461	6.11	5.49	4.49	20	4.30
Coal seam	5.0	1 440	4.67	4.47	3.40	26	3.06
Siltstone	10	2 873	9.18	8.75	7.51	30	6.65