Abstract: To study the seismic dynamic response of overlapped tunnels crossing through landslide body, a 1∶100 vibration platform test is conducted. The dynamic strain and acceleration are used to evaluate the dynamic response of tunnel lining and analyze the dynamic response of surrounding rock respectively, and then the fast Fourier transform and wavelet packet are used to discuss the spectrum response. The results show the following: (1) The sensitivities of the overlapped tunnels′ lining structures to the seismic waves vary. The strain response of the outer surface of the tunnel lining mainly occurrs at the right arch waist and left arch foot. However, the damage of the inner surface of the upper tunnel lining is mainly in the left arch waist, while the damage of the lower tunnel lining is mainly in the right arch waist. The stresses on the inner and outer surfaces of tunnel lining vary, which will easily induce lining damage. (2) The upper tunnel structure has a certain amplification effect on the seismic wave when the ground motion input is large (0.3g~0.6g), and the acceleration response of each measuring point has an obvious amplification effect along the elevation direction. Furthermore, the acceleration response of the crown and invert of the upper tunnel is greater than that of the lower tunnel, indicating that the upper tunnel should be the focus of attention in the process of earthquake resistant design. (3) The crown and invert of the tunnels are mainly affected by the seismic waves in the 1st2nd frequency band (0.20~12.52 Hz), while the seismic waves above 25.02 Hz have little impact on the overlapped tunnels. Additionally, the band energy distribution characteristics of the upper and lower tunnels are significantly different.

Key words: overlapped tunnels, vibration platform test, strain response, acceleration response, spectrum response