Intelligent Autofeedback and Safety Early-Warning for Underground Cavern Engineering during Construction Based on BP Neural Network and FEM

Table 2

The design value of physical and mechanical parameters.

Rock type	Young’s modulus (GPa)	Poisson ratio	Cohesion (MPa)	Friction degree (°)	Density (kg/m^3)
III	6.5	0.21	0.95	43.4	2500
IV	4.5	0.23	0.60	36.5	2520
V	1.5	0.25	0.25	24.2	2610