Analysis of Effect of Voids behind the Tunnel Lining by the Impact-Echo Method

Rongning Cao, Meng Ma, Sulei Zhang, Chao Niu

Abstract


The voids behind the tunnel lining, as one of the tunnel diseases, can influence the tunnel service life. For existing running tunnels, it is essential to evaluate the effect of the void condition. In this paper, the impact-echo method was employed to check the voids. Firstly, a tunnel-soil coupled finite element model was built. Then, an impact excitation was applied on the tunnel lining. The responses beside the impact locations were compared for the conditions with different sizes of void and without voids behind the tunnel lining. The responses of the conditions with various impact locations were also be contrasted. The signals were analysed in time domain, frequency domain, and time-frequency domain. In addition, the dynamic stiffness of the tunnel-soil structure and fractal box-counting dimensions of the vibration response were calculated as well. By analysing these responses, the results suggest that the existence of void induce a dominant frequency, lower resistivity to deformation and lower attenuate velocity. With the increase of the size of the void, the features of response are more obvious.


DOI
10.12783/dtmse/ictim2017/9941

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