Mathematical Problems in Engineering / 2015 / Article / Tab 4

Research Article

Collapsed Shape of Shallow Unlined Tunnels Based on Functional Catastrophe Theory

Table 4

PFC parameters of the surrounding rock after calibration.

NameNotation Value

Ball density (kg/m3)2940
Ball minimum radius (m)0.05
Ratio of maximum to minimum radius1.5
Normal contact stiffness of the ball (Pa)5.6 × 108
Contact stiffness ratio of the ball10
Ball-ball contact modulus (Pa)5 × 109
Ball friction coefficient0.5
Normal strength of the contact bond (Pa)2 × 104
Contact-bond strength ratio/1

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