Multi-point Shaking Table Test on Shield Tunnels in Consideration of Wave-passage Effect

In order to investigate the longitudinal seismic response law of long shield tunnel in consideration of wave-passage effect, taking the Shanghai Riverine Passage Shield Tunnel as a prototype, a series of multi-point shaking table tests were designed and conducted by the multifunctional shaking table array. In consideration of the scale of the actual shield tunnel and the capability of the multi-point shaking table system, the geometry similitude ratio was identified as 1: 60. Based on Buckingham-π theory and dimensional analysis, dynamic similitude relations of model soil and model structure used in the tests were determined. To simulate the longitudinal wave-passage input along the tunnel structure, segmental model container was designed and fabricated. The total length of the container was 22 m, made up of 4 driving boxes and 3 driven boxes. The boxes were connected by spring hinges. A mixture of sand and sawdust with the certain mass ratio was used to optimize model soil, and was validated through dynamic tri-axial tests. PE was selected as the model material and the similitude ratio of soil-structure relative stiffness was considered as a controlling index. By dint of the stiffness equivalency theorem, a multi-scale structural model of the shield tunnel was designed and fabricated. During the tests, Shanghai artificial wave was regarded as input. The seismic response regularities of shield tunnel models under wave-passage effects were evaluated through a series of multi-point shaking table tests. Test data including acceleration response of model soil and model structure as well as deformation response of circumferential joints in the tunnel was recorded. Dynamic responses of the tunnel structure under uniform input and wave-passage input were compared and analyzed. The results show that the seismic excitation considering wave-passage effect significantly aggravates the acceleration response of segments in the tunnel and the deformation response of circumferential joints, resulting in the risk of the failure of the tunnel during earthquakes. The non-uniform excitations of earthquake, especially wave-passage effect, should be particularly considered in the aseismic design of shield tunnels.