Ground Vibration Induced By High-Speed Train Running Inside Underground Tunnel Using Wheelset-Dropping Excitation Experiment And Numerical Study

With the rapid development of high–speed railway in China and the acceleration of urbanization,underground sections have inevitably appeared in high–speed railway.Due to the high operating speed of high–speed trains,the dynamic interaction between wheels and rails is very intense,and the propagation and attenuation laws of vibration via the path of "track–tunnel–soil" are different from previous studies.Therefore,it is important to study the ground vibration induced by high–speed train running inside underground tunnel.In this thesis,numerical and experimental investigations are carried out focusing on the ground vibration induced by underground high–speed railway.The main research work of the thesis includes:(1)The development of high–speed railway in China and the environmental vibration problem caused by moving train are briefly introduced,and then the research status of the environmental vibration problem caused by moving train are summarized from two aspects:theoretical research and experimental research,respectively.(2)An in-situ wheelset dropping excitation test is carried out in a double–line tunnel of a high–speed railway to obtain the excitation force and the ground vibration,the propagation and attenuation laws of ground vibration in the longitudinal,lateral and vertical directions are analyzed.(3)The train–track vertical coupled dynamics model and the track–tunnel–soil three–dimensional finite element model are established based on the vehicle–track coupled dynamics theory and finite element theory respectively.The dynamic wheel–rail force is used as a link to connect the two subsystems,further,the model is verified using measurement data to ensure the reliability of the calculation results.(4)The ground vibration caused by underground high–speed railway is simulated,then the ground acceleration and displacement under typical working conditions are analyzed,and the influence laws of train operation speed and tunnel buried depth on ground vibration are studied.The results show that the ground vibration caused by underground high–speed railway mainly concentrates within 100 Hz,and the vibration attenuates obviously during the propagation from vibration source to far field.With the increase of train speed,the ground vibration will also increase.For every 25 km/h increase in speed,the vibration level of longitudinal,lateral and vertical vibration increases about 1.5 dB,1.1 dB and 1.2 dB respectively.The ground vibration will also gradually decrease with the increase of tunnel burial depth.Meanwhile,the tunnel burial depth has a certain influence on the location of the vibration amplification zone existing in the soil.The ground displacement is less affected by train speed and tunnel burial depth.(5)On the basis of the aforementioned model,a numerical model is established using wave impeding block(WIB)for vibration control,and the influence law on their vibration reduction effect of key parameters of WIB is analyzed.The research results show that the WIB can effectively reduce the ground vibration caused by the train operation in the tunnel.The wider and deeper the burial WIB(when the vibration source is located below the WIB),the better the vibration reduction effect.However,when the width and depth are too large,there will be an amplifying effect on the ground vibration in the far field.In this thesis,the best vibration reduction effect is achieved when the width of the WIB is 15 m and the burial depth is 13 m(the tunnel burial depth is 14 m).According to the analysis of the WIB material,rubber and porous polystyrene have the best vibration reduction effect.In the close place to the vibration source,the WIB has a good vibration reduction effect above 5 Hz.In the far field positions,the WIB has a significant vibration reduction effect from 5 Hz to 12 Hz,but has no obvious influence on the high–frequency components.