Abstract: Joints in immersed tunnels typically exhibit low stiffness and are prone to significant deformation during earthquakes, posing serious risks to tunnel safety. Previous studies have demonstrated that dampers can effectively reduce the dynamic response and earthquake-induced damage to segment joints. The authors propose a novel damper utilizing nanofluidic material, designed to enhance the energy dissipation characteristics of immersed tunnel segment joints. Using the open-source finite element computational platform OpenSees, a three-dimensional simplified mechanical model of the joint is developed. In this model, the rigid end heads on both sides of the joint are represented using defined nodes, while the GINA gasket and shear keys are simulated using nonlinear springs connecting these nodes. The model accurately describes the mechanical behavior of the joint. The authors further compare the energy dissipation characteristics of joints with and without the nanofluidic damper. The results reveal the following: (1) The equivalent spring model effectively simulates the nonlinear behavior of various components within the immersed tunnel joint. (2) The inclusion of the nanofluidic damper significantly enhances the joint′s energy dissipation capacity, improves the performance of vertical and horizontal shear keys, and markedly increases the axial stiffness of the joint.

Key words: immersed tunnel, segment joint, nanofluidic dampers, energy dissipation characteristics