English：

During the construction of a new highway underpassing the existing high⁃speed railway bridge,the foundation disturbance may cause the deformation of the superstructure and affect the safety of thetrain operation. Based on a bridge project of the Yinchuan⁃Xi􀆳an High⁃speed Railway, from theTaiyangshan Development Zone to the Pengyang Section of the Yinchuan⁃Kunming Expressway, combinedwith on⁃site monitoring data and simulation, the dynamic response characteristics of high⁃speed railwaybridge structure caused by underpassing construction are systematically analyzed. By establishing a three⁃dimensional finite element model, the construction stages of highway foundation pit excavation, pilefoundation pouring, structural layer paving, etc. , are simulated, and a train running load of 200 ~350km / h is considered. The results indicate that the highway construction leads to obvious upwarp andsettlement changes in the main girder and rail top of the bridge, and the maximum vertical displacementis up to ± 1. 5mm. The increase in train speed will amplify the vertical vibration response of the mainbeam and the fluctuation of the tensile stress at the bottom of the beam, and the influence of theconstruction stage on the structural stress is significantly different.