Optimization for U-Shaped Steel Support in Deep Tunnels under Coupled Static-Dynamic Loading

Figure 24

Vertical stress variation under different stress concentration factors at different spacings. The black curve represents the equivalent stress of U-shaped steel under the concentration stress coefficient of 1, the red curve represents the case where the concentration stress coefficient is 3, the blue curve represents the case where the concentration stress coefficient is 6, the pink curve represents the concentration stress coefficient of 9, the green curve represents the concentration stress coefficient of 12, and the brown represents the yield stress of U-shaped steel.