Table 2 Physical and mechanical calculation parameters.

From: Mechanisms and optimization of system bolts in shallow four-track HSR tunnels based on deformation pressure theory

Materials

Elasticity modulus (GPa)

Density(kg/m3)

Poisson’s ratio

Cohesive force(kPa)

Internal friction angle (°)

Primary support

27.33

2550

0.2

–

–

Temporary support

29.65

2500

0.2

–

–

Class III rock

1.72

2300

0.26

2232

24.3

Class IV rock

0.73

2200

0.30

1372

16.9

Class V rock

0.35

2000

0.33

245

9.1

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