Load responses of semirigid and semiflexible segment joints in submerged floating tunnels

Abstract

Submerged floating tunnels (SFTs) have garnered significant attention because of their application potential. The joints between segments of a submerged floating tunnel are critical and vulnerable components of the overall structure. The mechanical properties of the joints significantly impact tunnel safety and service life. The structural configuration of semirigid and semiflexible joints in SFTs has been introduced and preliminarily studied. However, there are currently few publications discussing the analysis methods for the load responses of these joints in SFTs under external combined loads, as well as the mechanical mechanisms underlying structural behavior. Therefore, a three-dimensional numerical model for semirigid and semiflexible joints in SFTs is established in this paper, and the stress-strain characteristics of the flexible material (gasket) have been accurately simulated based on the hyperelastic constitutive relationship. A three-dimensional numerical simulation method is proposed to assess the load-bearing responses of semirigid and semiflexible joints, and stress states of segment joints in complex marine service environments are considered. Furthermore, the load-bearing responses of the segment joint structure under various loading conditions were explored, including axial load‒axial load, axial load‒shear load, axial load‒moment load, axial load‒torsion load, and axial load‒shear load‒moment load. The findings reveal that the axial load on the segment joint predominantly influences the load modes under composite loading. After exceeding the threshold, composite loads will lead to excessive stress in the segment joint, gasket failure, and excessive rotation angles within the segment joint structure. The research results of this paper yield valuable reference data and a theoretical foundation for practical design in SFTs engineering.