Numerical Study of Damage to Rock Surrounding an Underground Coal Roadway Excavation

Table 2

The macro-micro parameter calibration for the strength parameters of the different lithologies.

Lithology	Macrostrength parameter			Microstrength parameter
	E (GPa)	μ	UCS (MPa)	Eb (GPa)	Ec (GPa)		τc (MPa)	σc (MPa)
Fine sandstone	0.94	0.32	13.57	0.650	0.650	2.75	7.90	7.90
Siltstone (roof)	0.48	0.26	9.24	0.320	0.320	2.23	5.50	5.50
Mudstone (roof)	0.14	0.22	2.53	0.093	0.093	1.89	1.53	1.53
4^−2 coal	0.14	0.29	1.40	0.095	0.095	2.49	0.79	0.79
Mudstone (floor)	0.14	0.22	2.53	0.093	0.093	1.89	1.53	1.53
Siltstone (floor)	0.48	0.26	9.35	0.320	0.320	2.23	5.57	5.57

E is Young’s modulus; μ is Poisson’s ratio; UCS is the unconfined compressive strength; E_b is the bond effective modulus; E_c is the contact effective modulus; is the normal-shear stiffness ratio; τ_c is the shear bond strength; σ_c is the tensile bond strength.