Shaking table tests on the seismic performance of prefabricated T-shaped cross utility tunnel

Abstract

The seismic performance of the intersection of a T-shaped cross utility tunnel is weak under earthquake excitation. This study is the first to perform 1/20 scaled shaking table tests on the seismic performance of prefabricated T-shaped cross utility tunnel based on an actual utility tunnel project. Micro-concrete was used to create prefabricated utility tunnel models, and a prefabricated T-shaped cross utility tunnel was assembled by a T-shaped intersection and prefabricated utility tunnel segments using bolts. The laminar shear model box was used in the tests, and earthquake excitations along the two principal axes of the prefabricated T-shaped cross utility tunnel were inputted respectively at the bottom of shear box. The model soil acceleration, prefabricated utility tunnel strains, and opening and dislocation of joints were tested and analysed. Numerical simulation was conducted on the test cases, the test and numerical results were in good agreement. The results showed that the significant strain concentration on the T-shaped intersection or its adjacent utility tunnel was found under earthquake excitations along the two principal axes of the T-shaped utility tunnel, owing to incompatible deformation caused by the difference in lateral stiffness between two intersecting utility tunnels. The amplification of the axial strain at the T-shaped intersection or its adjacent utility was up to 5.2–6.4 times. Under earthquake excitations along the two principal axes of the T-shaped utility tunnel, the significant opening or dislocation of joint between the T-shaped intersection and prefabricated utility tunnel was found. The closer the joint was to the T-shaped intersection, the larger the opening or dislocation of joint. The amplification of the dislocation or opening of joint between the T-shaped intersection and prefabricated utility tunnel was 5.7–10 times. This study provides a certain reference for the seismic design of T-shaped cross utility tunnel.