Mechanical and Deformation Characteristics and Optimization of Support Parameters for Superlarge-Span Tunnel: A Case Study from Laohushan Tunnel

Table 7

Optimized parameters of primary support.

Parameter	Steel rib model	Steel rib spacing (cm)	Shotcrete thickness (cm)	Primary support equivalent reduction material parameters
				Deformation modulus E (GPa)	Steel rib gravity (kN/m^3)	Poissonratio µ
1	I25b	80	30	27.7	23.3	0.22
2	H175 × 175	80	26	28.2	23.4	0.22
3	I22b	75	28	27.6	23.2	0.22