Research On Vibration Of Shanghai-Nanjing Intercity High-Speed Railway And Its Environmental Impact

ABSTRACT:With the increasing of railway network density and train speed, vibration problems induced by running trains become more serious. Excessive vibration can impacts the comfort and safety of running trains, the function and safety of surrounding structures, the normal lives of nearby residents, causes fatigue and yielding of rail, settlement of track structures, and disturbance of foundation soil, etc. The vibration problems of Shanghai-Nanjing intercity high-speed railway (SNHSR) are widely concerned, because SNHSR goes through many densely populated areas and soft soil areas, with the design speed of over300km/h. What’s more, certain sections of SNHSR are adjacent to the Beijing-Shanghai railway (BSR). The vibration problems of SNHSR are studied by combining theoretical analysis and field tests in this dissertation, and the major contents and results are as follows:(1) Vibration test of SNHSR is carried out, and the vibration response of rails, track plates, bed plates, bridge pier, subgrade and the surrounding ground are obtained by analyzing the test data in time domain and frequency domain respectively. The test results show that, train speed and structure type affect vibration obviously, while length and model of train don’t affect vibration obviously. The vibration of bed plates near bridge bearings is more intense, so more attention should be paid to the design and maintaining of the bed plates.(2) Four types of typical high-speed track spectrum density function are converted into time domain samples through the algorithm based on the equivalent power spectrum density in frequency domain. By comparing the SNHSR track irregularity with the typical high-speed track spectrums in time domain and frequency domain, the results show that, track irregularity amplitude and power spectral density of SNHSR are superior to that of the other four types of typical high-speed track spectrum.(3) A vehicle-track (ballastless track) coupling dynamics model is established, and the dynamic response of train is calculated by inputting the SNHSR track irregularity and the other four types of typical high-speed track spectrum into the model. The results show that, the dynamic response of train is increasing smoothly when track regularity is good, and rapidly when track regularity is bad with train speed. Running stability of train can be ensured at the speed of400km/h under the excitation of SNHSR track irregularity. (4) A track-foundation finite element model is established in order to calculate vibration response of ground soil, and accuracy of the model is verified by analyzing and comparing the calculated results with test results. Based on the models, the influences of soil characteristic, train speed and track irregularity to vibration are calculated and analyzed. The conclusions are as follows:the influences of foundation soil characteristics, train speed and track irregularity to vibration are obvious; the pile-geogrid structure composite foundation of SNHSR has a good reinforcing and damping effect, and the closer to the foundation reinforcement area the more obvious the effects are.10meters away from the center line of railway, the ground vibration acceleration peak value declines about33.8%.(5) A vehicle-track (ballast track) coupling dynamics model is established and the moving train axle load of BSR is calculated by using this model. A finite element model which contains the structures of SNHSR and BSR is established based on the extension of the track-foundation finite element model. The stress and cumulative plastic deformation of foundation soil are calculated under the moving train axle load of BSR and SNHSR. The results show that, under the worst condition, cumulative plastic deformation of BSR foundation soil, which are induced by the running train of SNHSR, increase about18.36%, the reduction of distance between the railway lines affect cumulative plastic deformation of BSR foundation soil obviously.The research method of combining theoretical analysis and field tests, and the theoretical models established according to the engineering situation of SNHSR, performed well when be applied to study the vibration problems of SNHSR. The research method and the theoretical models, which can also be used to study the similar engineering problems, have certain theoretical significance and reference values.