Experimental and Numerical Study on the Seismic Response of a Surface Frame Structure–Soil–Double-Tunnel System

Abstract

The interaction mechanisms of the underground tunnel passing through the surface structure for a short distance are complex, and there are hidden dangers, with the interaction between the two tunnels having a nonnegligible impact on the seismic performance of the structural system. To explore the interaction law of seismic response between the double tunnel and the surface structure, this study conducted a shake-table test on a surface frame structure–soil–double-tunnel interaction system with a basement, using an actual tunnel project in Zhengzhou, China, as the background. A three-dimensional (3D) numerical model of the system was established using the finite-element analysis software ABAQUS (2021) with the equivalent linear method, and the numerical model's reliability was verified by comparing with the test results. The verified numerical simulation was used to study the interaction between the structures in the system under six different prototype model cases. The research findings revealed that the tunnel's presence reduced the dynamic response of the structural system while amplifying the far-field dynamic response, and the interaction between the two tunnels increased the degree of this reduction and amplification. The frame structure reduced the soil dynamic response while amplifying the acceleration response and shear force of the tunnel. Additionally, the location of weak layers of the frame structure was influenced by the type of seismic wave inputted, while the diameter and crossing location of the tunnel had nonnegligible influences on the dynamic response of the structural system. The research results can serve as a reference to preliminarily determine the interaction laws of the seismic responses of a double-tunnel and adjacent surface frame structures.