Research On Running Safety Of High-speed Railway Bridge During Earthquake Under Different Site Conditions

China is a country with many earthquakes.Several of the high-speed lines need to cross earthquake-prone areas.As the ratio of bridges in high-speed lines increases,the probability of trains crossing bridges during the earthquake increases.In the case of a train derailment at high speed,it will cause incalculable loss of life and property.On the basis of summarizing the existing research,a dynamic model of train-bridge coupling system under earthquake is established in this thesis.The influence of site conditions on system dynamic response and running safety performance is discussed.The probability of train derailment under different seismic conditions is summarized.The main research contents are as follows:(1)Establish a coupled train-bridge vibration model.The field measurement of the simple-supported bridge of the Zhuzhou Xiangjiang Special Bridge of the Wuhan-Guangzhou Passenger Line using the interferometric radar system IBIS-FS.The vertical displacement and vertical acceleration of the 32 m span simple-supported bridge obtained from the field test measurements and model calculations were compared and analyzed.It is proved that the model can accurately analyze the dynamic response of the coupled train-bridge system,and can be used to study the influence of site conditions on the traffic safety of high-speed railway bridge under earthquakes.Finally,the first-order,second-order and third-order vibration frequencies of the 32 m span high-speed railway simple-supported bridge are obtained by Fourier transform.(2)The code response spectrum is determined according to the seismic design code.Then generate artificial seismic waves of 7-degree earthquake.The time-history response analysis of the coupled train-bridge system under earthquake action is carried out.The influence rules of different site conditions,seismic partitions and pier heights on the transverse displacement and acceleration of the high-speed railway bridges,transverse displacement and acceleration of the trains,transverse relative displacement of wheel-rail and derailment coefficients are obtained.(3)Generate randomly 30 seismic waves with different working conditions of 7-degree,8-degree and 9-degree earthquake.The effects of different seismic intensities,site conditions,seismic partitions and pier heights on the distribution of train derailment coefficients are calculated.The probability of train derailment under earthquake action is discussed.