Mechanical model and analytical solution for stiffness in the joints of an immersed-tube tunnel

Stiffness is one of the most important parameters in representing the performance of joints of an immersed tunnel. At present, neither analytical solutions nor experimental data are available to study joint stiffness in immersed tunnels. A mechanical model for element joints is proposed with assumptions based on the design characteristics of immersed joints, in which springs are assumed to model behaviors of GINA rubber and non-deformable rigid plates are assumed for segments. An analytical solution for joint stiffness is derived according to equations of stress equilibrium and deformation compatibility. A benchmark model, a three-dimensional refined model of an immersed joint, is used to calibrate the presented model and the derived closed-form solution for joint stiffness. Comparison under the same geometrical and material parameters shows a high degree of consistency between the two, which verifies both the presented model and analytical solution. Finally sensitivity analyses of parameters for joints are carried out using the proposed model, and potential influences of parameters on joint stiffness are predicted.