State-of-the-Art Seismic Studies of Loess Tunnels in China

Large earthquakes occur frequently around the world. Due to the fragility of loess, the effects of seismic events on loess tunnel projects have received considerable in-depth research attention. In this paper, we systematically review recent seismic research on loess tunnels and highlight deficiencies that require further study with a focus on the following topics: site selection, tunneling through landslides, shallow-buried tunnels with bias pressure, dynamic analysis, and seismic liquefaction. For tunnels constructed through loess landslides, comprehensive prevention measures should be implemented to ensure the stability of the landslide and tunnel. For shallow-buried loess tunnels with bias pressure, the lining of the deep-buried side should receive more attention than that of the shallow-buried side. It is necessary to consider the combined effects of seismic activity, rainfall, and train load on the stability and fortification of loess tunnels. The stress state of the surrounding loess should also be considered in further studies on tunnel liquefaction. Finally, the laboratory planar strain method should be simplified to address the discrepancy between laboratory and field results.