Dynamic response characteristics and failure mode of a bias loess tunnel using a shaking table model test

The shallow bias section at the tunnel portal is one of the most seriously damaged areas under earthquake conditions. The seismic responses of the loess slope and the tunnel structure interact in a bias tunnel-loess slope coupling system. In this study, a 1:25 large-scale shaking table model test on the bias loess tunnel is conducted, and the seismic responses and failure modes of the loess slope and bias tunnel are analyzed. Additionally, the interaction between the tunnel structure and loess slope is studied. The experimental results show: (1) Tunnel structure influences on the acceleration distribution characteristic of the slope. The closer the soil at the slope surface is to the tunnel, the higher the peak ground acceleration (PGA) amplification factor. (2) Slope also has an impact on the seismic response of the tunnel structure. The peak accelerations of the tunnel vault and the sidewall at the shallow-buried side are larger than those of the tunnel invert and the sidewall at the deep-buried side. (3) Under earthquake conditions, several tensile cracks appear in the slope top, and shear failure appear along the slope foot to the slope surface above the tunnel vault. (4) Hances and arch feet are easily damaged in an earthquake, and the seismic damage of lining at the deep-buried side is more severe than that at the shallowburied side.

Automated summary

The study found that the tunnel structure influences the acceleration distribution characteristic of the slope, while the slope also affects the seismic response of the tunnel structure. Under earthquake conditions, both the slope and tunnel exhibit varying degrees of damage.