Distribution Features of the Minimum Rock Cover Thickness of the Surrounding Rock Self-Stability of the Metro Tunnel in the Soil-Rock Dualistic Stratum

Table 1

The physical and mechanical parameters.

Types of stratum	Cohesion (MPa)	Internal friction angle (°)	Modulus of elasticity (GPa)	Poisson’s ratio	Density (kg/m^3)
Soft soil stratum	0.032	20	0.05	0.38	22.5
Rock stratum	0.60	35	5.0	0.25	24.5