Dynamic response analysis of submerged floating tunnel with flexible boundary under impact loading and cable-force adjustment study

This study, concentrating on the submerged floating tunnel (SFT) with flexible boundary, proposed a threedimensional coupled vibration model for the anchor cables and the tube under impact loading. The flexible boundary cable-tube coupled vibration model took into account the angular displacement of the tube and the variance in the dynamic cable forces experienced by the anchor cables on the both sides, utilizing Lagrange's equations for its formulations. The accuracy of the theory model was verified through finite element analysis, showing a great agreement. Building upon these findings, the study investigated the differences of the responses of the SFT with various boundary stiffnesses under impact loading, and explored the influence of cable-force adjustment on them, revealing that when the boundary stiffness was less than a certain critical value kc, the structural performance of the SFT after cable adjusting was worse than before adjusting. Furthermore, an analytical approach was proposed in this study to figure out the critical value kc.