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

Table 1

Mechanical indicators of similar materials of the surrounding rock.

Parameter	Specific weight γ (kN/m^3)	Elastic modulus E (GPa)	Cohesion C (kPa)	Poisson’s ratio μ	Internal friction angle φ (°)	Uniaxial compressive strength σc (MPa)
Prototype	25–27	20–33	1500–2100	0.2–0.25	50–60	57.33–76.95
Model	25–27	0.33–0.55	25–35	0.2–0.25	50–60	0.95–1.28
Material	22.28	0.524	27.16	0.19–0.22	58.38	1.104