Physical model test and numerical simulation for the interaction analysis between tunnel and masonry arch bridge

Masonry arch bridges serve as essential transport infrastructure and are often protected as cultural heritage sites. While most studies emphasize their response to vertical loading, limited attention has been given to their behavior under the influence of nearby tunnel excavation. This study investigates the interaction between tunnel-induced ground movement and masonry arch bridges through physical model tests and numerical simulations. Two typical arch bridge types are examined to assess deformation patterns caused by tunneling. A coupled discrete element and finite difference method is proposed to simulate soil–structure interactions, and the model is validated against experimental results. The results highlight that the arch span has a major impact on soil behavior. Larger spans lead to wider settlement zones and more uniform stress distribution but increase structural vulnerability. Semi-circular arches develop tensile strain at the crown and compressive strain at the foot under tunneling. Meanwhile, the joint displacements follow a three-dimensional Gaussian distribution, influenced by tunnel volume loss and burial depth, especially in circular arches. Increasing Young’s modulus and joint shear stiffness of masonry arch bridges through technical means, such as grouting, is helpful to reduce deformation and cracking. These findings support risk assessment and design improvements for masonry bridges in tunneling environments.