Dynamic response of underpass tunnel in soft soil subgrade beneath airfield pavement during aircraft taxiing loads

With the increasing number of shield tunnels constructed beneath airport taxiways, research on the long-term impact of aircraft taxiing loads on tunnel safety remains inadequate. Taking an airport project in East China as the background, a 3D coupled finite element-infinite element model is established in ABAQUS, in which aircraft taxiing loads are simulated by moving constant loads, and the dynamic response of the foundation and the mechanical characteristics of the tunnel structure are systematically investigated. Results show that the moving loads induce continuous rotation of the principal stress axis in the foundation, forming a typical "heart-shaped" deviatoric stress path and nonlinear stress attenuation with depth. Reinforcement with high-pressure jet grouting piles reduced the maximum vertical and horizontal displacements of the tunnel by 30.4% and 26.5%, respectively, demonstrating a remarkable reinforcement effect. These findings provide reference for the dynamic assessment and design of similar projects.