Experimental study on the mechanical response model of the vertical shear key under typical deformation of segmental joints of the in-service immersed tunnel

To investigate the mechanical response characteristics of the shear key of segmental joints in the in-service immersed tunnel under differential deformation conditions, this study conducted the physical model test with the similarity ratio of 1:10 on the self-developed large-scale model test platform for immersed tunnel joint deformations based on the immersed tunnel of Hong Kong-Zhuhai-Macao Bridge. After investigating the mechanical response characteristics of the vertical steel shear key of segmental joints in the typical deformation mode, this study proposed the mechanical response characteristics and weak bearing positions of the shear key in vertical shear, vertical bending, and lateral torsion deformation modes. After the comprehensive comparative analysis of multiple working conditions, the most unfavorable deformation working conditions for structural service were proposed. Furthermore, after tackling the bearing mechanical response of shear key combinations and shear force distribution. This study revealed the collective bearing mechanism of multiple shear keys in different joint deformation modes, and it proposed the shear force distribution ratio of shear keys in different positions under differential deformation conditions. The research findings can serve as a basis for the joint shear key design, bearing mechanical characteristics evaluation, monitoring indicator selection and monitoring point layout. Additionally, this study can provide an experimental platform, accumulate experimental experience, and offer guidance and reference for similar experimental studies.