Numerical analysis of partial impact forces of offshore submerged floating tunnel encountered submarine slide hazards

Abstract

Submerged floating tunnels (SFT) provide novel and practical solutions for cross-sea transportation. However, the operating environment of undersea infrastructures is complex. Easily triggered and widespread hazards, particularly submarine slides, may cause devastating damage to submerged floating tunnels. In this study, the forces caused by a submarine slide mass impacting a tunnel structure and the effect of the slide mass thickness on these forces were determined. A computational fluid dynamics (CFD) approach was employed to analyse the submarine slide-tunnel interaction, covering Reynolds numbers of 0.36–208. There is a significant difference between impact forces under the partial impact state (i.e., the thickness of slide mass is not enough to flood a tunnel structure) and the flooded impact state (i.e., the slide flow reaches symmetrical on the upper and lower sides of the tunnel). The effect of the slide mass thickness on the impact forces is limited to a well-defined range of approximately −1.5–8.0 times the tunnel diameter (considering the tunnel bottom as 0) for instantaneous impact forces and −0.5–4.0 times the tunnel diameter for continuous impact forces. An evaluation approach for determining the forces for partial submarine slide-tunnel impact is proposed.