Parametric comparative analysis of curved and straight submerged floating tunnels under wave loading

초록

To date, most research on submerged floating tunnels (SFTs) has been limited to straight geometries, whereas horizontally curved geometries remain insufficiently investigated in terms of both theoretical aspects and structural behavior, despite their potential benefits in improving stiffness through arch action. To address this research gap, this study derives the equations of motion and natural boundary conditions accounting for mooring lines. Subsequently, a comparative investigation of the structural behavior of curved and straight tunnels is carried out through finite element simulations. The structural responses of a 1 km-span tunnel were evaluated under two mooring configurations-vertical (Type 1) and inclined (Type 2)-with particular focus on maximum responses and arching effects, in order to identify the most rational mooring configuration. Additional analyses under Type 2 were performed to evaluate the effects of span length (1000 m, 2000 m, and 4000 m) and rise-to-span ratio on natural frequencies, bending moments, axial forces, and von Mises stresses. The results revealed that curvature induced an arching effect, redistributing internal forces induced by waves into axial forces and thereby significantly reducing structural responses. For the 4000 m span case, the maximum von Mises stress was reduced by as much as 87 %, remaining only 13 % of that observed in the straight tunnel. These findings demonstrate the structural efficiency of curved SFTs, particularly in long-span applications.

키워드