Excavation Sequence and Surrounding Rock Mass Stability of Large-Scale Underground Engineering with 8 Tunnels

Table 1

Geomechanical property parameters of the surrounding rock mass.

Grade	Density (g/cm^3)	Poisson’s ratio	Deformation modulus (GPa)	Friction coefficient	Cohesion (MPa)	Tensile strength (MPa)
I	2.6	0.18	12.0∼8.0	1.20∼1.10	2.00∼1.50	1.80∼1.20
II	2.6	0.20	8.0∼5.0	1.10∼0.90	1.50∼1.00	1.20∼0.80
III	2.6	0.25	5.0∼3.0	0.80∼0.75	0.80∼0.65	0.64∼0.52
IV	2.4	0.30	3.0∼1.0	0.70∼0.65	0.60∼0.40	0.48∼0.32