Multi-scale physical model of shield tunnels applied in shaking table test

Experimental simulation of long-distance shield tunnels is difficult due to the enormous volumes of segments and complexity of joints. In this paper, a multi-scale method is proposed to simulate the test model of shield tunnels, which discretizes the entire model structure into the segmental equivalent ring portion (SER) and the equivalent uniform tube portion (EUT). The EUT model is employed to capture seismic response characteristics of the entire tunnel system, whereas the SER model is employed to describe in detail the deformation responses in lining segments and joints at positions of potential damage or interest. The proposed multi-scale physical model for shield tunnels is validated through shaking table tests, in which a full refined model is set as benchmark for comparison. Results show that: 1) the multi-scale physical model demonstrates the same macroscopic dynamic response, such as acceleration responses of model linings, as the full refined model; and 2) dynamic responses such as the extension of joints in the central zone of SER portion of the multi-scale model is consistent with those in the full refined model. The proposed multi-scale method provides an effective way for the design of complex segmental tunnel models applied in shaking table tests.