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

Table 2

Physical mechanics and hydrodynamic parameters of rock mass in the fracture zone of the collapse column.

Collapse column (from bottom to top)	Elastic modulus, (GPa)	Shear modulus, (MPa)	Poisson’s ratio,	Cohesive force, (MPa)	Internal friction angle, (°)	Permeability, (×10^−11 m·s^−1)	Porosity,
First paragraph	19.3	11.2	0.35	3.9	33.20	7.87	0.5
Second paragraph	10.74	6.6	0.3	3.0	28.60	2.475	0.24
Third paragraph	11.7	6.96	0.32	3.3	28.40	5.28	0.3
Fourth paragraph	14.56	9.84	0.32	3.3	41.20	7.425	0.36