Upper Bound Solution of Safety Factor for Shallow Tunnels Face Using a Nonlinear Failure Criterion and Shear Strength Reduction Technique

Figure 4

Effect of and on the FOS for collapse failure mechanism ( = 5 kPa, = 20 kN/m³, = 10 kPa, = 24.73 kPa, = 0.2~1, = 1.0~2.0).

(a)

(b)