Force and Deformation Characteristics during the Reconstruction and Expansion of Shallow Single-Tube Tunnels into Large-Span Multiarch Tunnels

Table 2

Thickness and mechanical parameters of the prototype and model of the lining and middle partition wall.

Parameter	Initial support thickness (mm)	Secondary lining thickness (mm)	Middle partition wall thickness (mm)	Elastic modulus E (GPa)	Compressive strength Rb (MPa)
Prototype	250 + 80.4	450	2400	23–29.5	12.5–16.7
Model	5.5	7.5	40	0.38–0.49	0.21–0.28

Note. The initial support thickness of 80.4 mm is converted to the thickness of the shotcrete with the same compressive stiffness (EA).