Abstract: The modal analysis and vibration response of prefabricated middle partition walls in large-diameter shield tunnels under train vibration load and aerodynamic load are investigated. Numerical simulation methods based on fluid mechanics calculation software are used to systematically examine the influence of single-vehicle travel and double-vehicle intersection on the aerodynamic effects of the middle partition wall, obtaining aerodynamic load time-history curves. In addition, the dynamic finite element method is utilized to analyze the modal vibration mode and vibration response of the prefabricated middle partition walls. The results reveal the following: (1) When a single train travels at a speed of 160 km/h, the pressure changes at each measuring point in the tunnel are consistent, with the maximum pressure occurring at the monitoring point of 1/3 tunnel length from entrance. When two trains intersect, the pressure amplitude on both sides of the partition wall changes inconsistently, leading to differences in the pressure curves. (2) As the burial depth of the tunnel increases, the bending modal frequency of the middle partition wall slightly decreases, and the vertical displacement response is significantly stronger than the horizontal displacement response. The frequency corresponding to the first-order bending mode of the prefabricated middle partition wall ranges between 16.106 6 and 17.141 9 Hz, differing from the main frequency range of 0－2 Hz observed in the tunnel wall during on-site testing. This indicates that the prefabricated middle partition wall poses no resonance risk under fixed constraint. (3) The vibration effect of the middle partition wall is primarily influenced by the train load, whereas the aerodynamic load has a relatively minor impact on the vibration response.

Key words: large-diameter shield tunnel, prefabricated middle partition wall, train vibration load, aerodynamic load, aerodynamic effect, vibration response, numerical simulation