Analysis on the Influence of the Bridge Foundation under Scouring on the Natural Vibration Characteristics of Piers

In order to analyze the natural vibration characteristics change of the pier when the bridge foundation was scoured,the 5th pier of the 2K+614 m bridge on the Xiachengzi-Jixi Railway was tested by the impact vibration test method (IVTM),and the scouring effects on the pier were simulated by excavating different depths of the covering subsoil around the pier.Test analysis shows that the natural vibration frequency of the pier decreases and the rigid body swing characteristics of the pier strengthen with the decrease of the covering subsoil depth around the pier,and the decrease of the soil body near land surface is more effective to the natural vibration frequency of the pier.The finite element model is presented by simulating the constraints of the subsoil around the pier with elastic coefficients.The effect of the covering subsoil depths on the constraints of the subsoil around the pier can be described by adjusting the elastic coefficients.The results can be obtained from the finite element model,energy method,and regression method by comparing with the measured results.It shows that the finite element model can better forecast the effect on the natural vibration characteristics under the pier scouring than the other two methods.