The Effect of Key Design Parameters on the Global Performance of Submerged Floating Tunnel under Target Wave and Earthquake Excitations

• Published in: Computer modeling in engineering & sciences Vol. 128; no. 1; pp. 315 - 337
• Main Authors: Jin, Chungkuk, Kim, MooHyun
• Format: Journal Article
• Language: English
• Published: Henderson Tech Science Press 01.01.2021
• Subjects: Boundary conditions; Bwr; Design parameters; Design waves; Earthquake; Earthquakes; Excitation; Finite element method; Formability; Mathematical models; Mooring; Mooring Interval; Mooring Tension; Parameter sensitivity; Performance evaluation; Random waves; Resonant frequencies; Seismic response; Snap Loading; Springs (elastic); Submerged Floating Tunnel; Submergence Depth; Tunnel Length; Wave
• ISSN: 1526-1492; 1526-1506; 1526-1506
• DOI: 10.32604/cmes.2021.016494

This study presents a practical design strategy for a large-size Submerged Floating Tunnel (SFT) under different target environments through global-performance simulations. A coupled time-domain simulation model for SFT is established to check hydro-elastic behaviors under the design random wave and earthquake excitations. The tunnel and mooring lines are modeled with a finite-element line model based on a series of lumped masses connected by axial, bending, and torsional springs, and thus the dynamic/structural deformability of the entire SFT is fully considered. The dummy-connection-mass method and constraint boundary conditions are employed to connect the tunnel and mooring lines in a convenient manner. Wave- and earthquake-induced hydrodynamic forces are evaluated by the Morison equation at instantaneous node positions. Several wave and earthquake conditions are selected to evaluate its global performance and sensitivity at different system parameters. different BuoyancyWeight Ratios (BWRs), submergence depths, and tunnel lengths (and mooring intervals) are chosen to establish a design strategy for reducing the maximum mooring tension. Both static and dynamic tensions are critical to find an acceptable design depending on the given target environmental condition. BWR plays a crucial role in preventing snap loading, and the corresponding static tension is a primary factor if the environmental condition is mild. The tunnel length can significantly be extended by reducing BWR when environmental force is not that substantial. Dynamic tension becomes important in harsh environmental conditions, for which high BWR and short mooring interval are required. It is underscored that the wet natural frequencies with mooring are located away from the spectral peaks of design waves or earthquakes.