Vibration Characteristics Study And Simulation Analysis Of Culvert-subgrade Transition Section Under High-speed Train Loading

In recent years,many countries are developing high-speed railways,among which the construction level of China's high-speed railways is in the leading position in the world.With the continuous improvement of high-speed train speed,high-speed railway lines put forward higher requirements for the smoothness and stability of subgrade structure.As an important part of high-speed railway,the roadbed of transition section affects the smoothness of the line,so the study of its dynamic characteristics is of great significance.Based on the project of National Natural Science Foundation of China,the time-domain and frequency-domain analysis of dynamic response test results of roadbed under real vehicle operation and three-dimensional dynamic simulation calculation of vehicle-track-roadbed are carried out for a culvert-roadbed transition section of Wuhan-Guangzhou high-speed railway.The vibration response characteristics of the transition section under high-speed train operation are studied.The main work and conclusions of this paper are as follows:(1)Based on the test results of the subgrade dynamic response of the transition section under actual driving conditions,the distribution law of the dynamic response time domain amplitude along the train running direction and the subgrade depth direction,and the time-domain amplitude of the vehicle speed and axle load on the subgrade dynamic response are obtained.Influence the law.The results show that the dynamic stress of the subgrade increases linearly with the increase of the vehicle speed;the dynamic response of the subgrade decreases obviously along the depth direction,and the influence of the vehicle speed on the dynamic stress of the subgrade decreases with the increase of the depth.(2)The vibration amplitude frequency curve and vibration energy distribution of the transition section are analyzed.The distribution law of the frequency domain characteristics of the subgrade dynamic response along the line is obtained.The influence of train speed on the frequency domain characteristics of the subgrade vibration is discussed.The results show that the dominant frequency of subgrade vibration is mainly caused by periodic wheel load;the increase of vehicle speed is more significant for the vibration energy of higher frequency band.(3)By comparing the dynamic response spectrum characteristics of the subgrade under the action of the EMU and the track inspection vehicle,the influence of the axle load on the dynamic response spectrum characteristics of the transition subgrade is studied.The results show that the dominant frequency of the track inspection vehicle is more concentrated than that of the EMU.(4)Based on the test part of the above transition section,the vehicle-tracksubgrade three-dimensional dynamic numerical analysis model is established and compared with the test results to verify the rationality of the model.The distribution of dynamic response along the cross section of the subgrade and along the depth of the subgrade is analyzed.The influence of train speed and axle weight on the time domain amplitude of the dynamic response is discussed.The results show that the dynamic stress and vibration acceleration of the subgrade are exponentially attenuated along the depth direction of the subgrade;the dynamic stress amplitude increases linearly with the increase of the vehicle speed.