Study on seismic response of a large-scale shield tunnel with an innovative loading device based on shaking table test

This paper presents the development of a large-scale tunnel model using an innovative loading device, which is then subjected to longitudinal seismic response analysis through a shaking table test. The loading device, designed to support the tunnel with springs, applies seismic loads from the shaking table and simulates the soil-structure interaction. Initially, the rationality and accuracy of the loading device were validated through numerical and analytical methods. Experimental results reveal that, under various seismic excitations, the acceleration response is significantly lower at the tunnel ends compared to the middle. The tensile strain response at the arch waist exhibits a U-shaped deformation along the longitudinal axis, while the compressive strain response exhibits a bending deformation with multiple inflection points. Furthermore, both tensile and compressive strain responses at the arch bottom show more pronounced bending deformations along the longitudinal direction. The findings indicate that the peak value of the input seismic excitation does not alter the deformation pattern of the tunnel. Within the longitudinal length L of the tunnel, the tensile zone reaches a maximum strain value ε_max, whereas the compressive zone reaches a minimum strain value ε_min. These experimental insights offer valuable references for the seismic design of tunnels.