Calculation Model and Influencing Factors of Surrounding Rock Loosening Pressure for Tunnel in Fold Zone

Figure 14

Relationship between the friction angle () and vertical surrounding rock loosening pressure (q). 1— = 1.0; 2— = 1.1; 3— = 1.2; 4— = 1.3; 5— = 1.4; 6— = 1.5.