Dynamic responses of loess tunnels with different cross sections under the action of earthquakes, rainwater seepage and trains

Four tunnel models with different cross sections were established, and the models were coupled with fluid models to investigate rainwater seepage-, earthquake- and train-induced effects. The displacements, stresses and pore water pressures of key points in the loess tunnels were analyzed, and the dynamic response patterns of loess tunnels under the influence of earthquakes, rainwater seepage and train loading were obtained. The results show that the dynamic responses of loess tunnels with different cross sections vary. Although the patterns of acceleration and displacement in the four loess tunnel sections are basically identical, the peaks of acceleration and displacement are lowest in the circular tunnel and highest in the rectangular tunnel. Furthermore, obvious stress differences exist among the different sections. The stress is lowest in the circular loess tunnel, intermediate in the curved-wall and straight-walled arch tunnels, and highest in the rectangular tunnel. The pore water pressures of loess tunnels increase with increasing depth, but the differences are not large. Shaking-table testing of a curved tunnel was carried out, and the results were consistent with the numerical results.