Shaking table test on damping layer applied in tunnel crossing #br#
soft and hard surrounding rock
Fan Kaixiang1 Shen Yusheng1 Gao Bo1 Zheng Qing1 Yan Gaoming1 Wang Shuaishuai1,2 Huang Haifeng1
1. Key Laboratory of Transportation Tunnel Engineering of the Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China;
2. CCCC Second Highway Engineering Co., Ltd., Xi’an 710065, China
Abstract：A certain case of a shallow road tunnel in high-intensity area of western China is taken as an example, the dynamic response characteristics of tunnel trunk and the segment crossing the hard-soft interface were studied based on the large-scaled shaking table tests and verified by the numerical simulation. The results show that there is an optimal thickness of damping layer for tunnel trunk and the soft-hard rock section. The increase of the thickness of damping layer will reduce the differences in the dynamic response toward the longitudinal direction. The acceleration response spectrum curves of the tunnel crown surrounding rock and lining show the phenomenon of “three peaks”. Spectral features of the surrounding rock can not be changed significantly by installing damping layer. The responses of the lining mainly depend on the dynamic feature of the outside rock without reflecting its self-vibration characteristics distinctly. The dynamic responses of tunnel can be reduced by absorbing low-frequency components with the damping layer of optimal value. The setting of the damping layer can significantly reduce the stress of the second lining with different degrees of amplification in initial support. With the increase of the thickness of the damping layer, the dynamic stress of the second lining decreases first and then increases while that of initial support shows the opposite trend. By observing the damage form of lining, it is found that the crown, arch foot, and arch of the tunnel are easy to crack. After installing the damping layer, he invert arch is relatively easy to crack, so more attention should be paid. The research results can provide a reference for aseismic design of shallow tunnels in the western high-intensity earthquake area.
