Failure Depth of a Floor of a Fully Mechanized Working Face When Passing a Collapse Column

Table 1

Mechanical properties of coal and rock.

Lithology	Cohesive force (MPa)	Internal friction angle (°)	Uniaxial compressive strength (MPa)	Elastic modulus (GPa)	Poisson’s ratio	Tensile strength (MPa)
K8 sandstone	12.89	34.70	92.10	25.35	0.20	15.54
Mudstone	3.16	41.30	34.51	9.87	0.25	4.93
K2 limestone	15.50	47.20	91.75	27.56	0.21	15.82
Siltstone	5.36	42.50	35.28	10.45	0.24	5.19
#10 coal	0.48	43.70	7.65	2.96	0.30	0.86
Fine sandstone	7.69	40.60	45.68	15.36	0.23	7.85