Dynamic response analysis of submerged floating tunnel - canyon water system under earthquakes

Abstract Submerged Floating Tunnel (SFT) is one new type of infrastructure, representing a challenge in structural engineering, both on the theoretical and operational fields. Several research work focused on this innovative structure, especially on effects of dynamic loadings such as earthquakes and sea waves. So far, the dynamic response of SFT under vertical seismic ground motion input and secondary hydrodynamic pressure has been studied deeply using theoretical and numerical methods. However, the dynamic response characteristics of SFT-Canyon water system under surging caused by the canyon horizontal sloshing motion remain unclear. In this paper, a new mathematical model for analyzing the dynamic response characteristics of SFT-Canyon water system caused by horizontal sloshing motion was proposed, which considered the transmission effect of canyon water to the original horizontal input seismic wave. Firstly, the canyon was simplified as a rectangular water tank and hydrodynamic potential flow theory was used to study the dynamic input to SFT through canyon water. After that, based on the theory of structural dynamics, SFT was simplified as an elastic support beam, and the action of horizontal seismic input was considered as the load transmitted through the fluid in the canyon to study the response of SFT transmitted through water. Finally, we used verified MATLAB coding to achieve Duhamel integration to solve the mathematical model of the system dynamic response under the action of sine wave and seismic wave respectively. Besides, the factors affecting the maximum vertical displacement response of SFT under hydrodynamic pressure caused by horizontal seismic input to the canyon were discussed.