Feasibility study on buoyancy–weight ratios of a submerged floating tunnel prototype subjected to hydrodynamic loads

Abstract

The research progress of a novel traffic solution, a submerged floating tunnel (SFT), is reviewed in terms of a study approach and loading scenario. Among existing publications, the buoyancy–weight ratio (BWR) is usually predefined. However, BWR is a critical structural parameter that tremendously affects the dynamic behaviour of not only the tunnel tube itself but also the cable system. In the context of a SFT prototype (SFTP) project in Qiandao Lake (Zhejiang Province, China), the importance of BWR is illustrated by finite element analysis and subsequently, an optimized BWR is proposed within a reasonable range in the present study. In the numerical model, structural damping is identified to be of importance. Rayleigh damping and the corresponding Rayleigh coefficients are attained through a sensitivity study, which shows that the adopted damping ratios are fairly suitable for SFTP. Lastly, the human sense of security is considered by quantifying the comfort index, which helps further optimize BWR in the SFTP structural parameter design. Submerged floating tunnel is a novel traffic solution. In the prototype project in Qiandao Lake, the importance of buoyancy–weight ratio (BWR) is illustrated. Subsequently, BWR of 1.2 could be the most promising choice based on dynamic responses and human senses of security and comfort.