A Case Study of Tunnel Reinforcement Measure during Traffic Upgrading in Chongqing City, China

Table 1

Physical and mechanical parameters of surrounding rock.

Rock classification	Density, γ (kg/m^3)	Elastic modulus, E (MPa)	Poisson’s ratio, (μ)	Cohesion, c (kPa)	Friction angle, φ (°)
Ⅳ	2,500	1,050	0.33	350	19.6

Notes. Classification of the surrounding rock was based on the specification [38], which considered the joints, rock strength, groundwater, etc.