Shaking table test study on dynamic response of tunnel crossing through slope

To study the seismic dynamic response characteristics of the tunnel crossing slope，a shaking table test was designed and carried out. The acceleration and dynamic strain responses of the cross tunnel and the slope are analyzed based on the test results. The spectral characteristics of the slope are analyzed quantitatively by introducing the Hilbert-Huang transform. The conclusions are as follows：(1) The acceleration responses of cross tunnel structure exhibit significant regional differences. Furthermore，the acceleration response is particularly intense at the crown and invert of the upper-span tunnel，the intersection，and the portal section of the under-crossing tunnel. (2) The tunnel lining is subjected to tensile-compression cyclic loading under earthquake. Additionally，the crown and invert of the upper-span tunnel bear relatively large pressure. The seismic additional moment is mainly concentrated in the left arch waist and invert，which should be the main seismic fortification area. (3) There is a synergistic deformation effect between the tunnel structure and the slope when the tunnel crosses the slope. The presence of the upper-span tunnel will accelerate or worsen the seismic damage in the middle and upper parts of the slope. Simultaneously，the seismic inertia force and landslide thrust are counteracted on the tunnel structure in the process of slope deformation and instability，resulting in lining damage or even failure. (4) The marginal spectral amplitude of each measurement point increases with the increase of elevation. The filtering effect of seismic waves is different for rock stratum interface such as bedrock，weak interlayer，slope，and lining structure. Furthermore，the spectral composition of seismic wave has transformed，resulting in a sharp change of marginal spectral amplitude. (5) The seismic energy response of each measuring point migrates to a relatively low frequency with the increase of the input seismic amplitude. The marginal spectral amplitudes of the crown of the upper-span tunnel and top of the slope show multiple peaks whose abrupt changes are the most pronounced. It shows that the upper part of the slope，especially the crown of the upper-span tunnel and top of the slope，is a sensitive area under seismic loading. © 2022 Academia Sinica. All rights reserved.