Environmental Vibration Induced By Rail Transit And Vibration Reduction Measures

In recent years,the rapid development of rail transit facilitates the travel of people.But at the same time the high-speed train will lead to greater environmental vibrations.Because of elevated rail needs small footprint and helps control sedimentation,high-speed railway often constructes in the form of elevated track when it passes the area of densely industrial or populated in residential.So the study of vibration characteristics caused by elevated rail is extremely important.Therefore,this paper discusses the the vibration characteristics of high-speed railway viaduct by the FEM and results of field trials.Based on the purpose of vibration control,this paper uses the Zhejiang University full scale model test equipment for high speed railway to study the vibration characteristics of the floating slab track on high speed railway subgrade.The damping effect of the slab is also analyzed.The main contents and research results are as follows:(1)This paper establishs a viaduct foundation-soil coupled finite element model according to Tainan Science Park excitation field test which is done by Cheng-Hsing Chen.The boundary all around is modelled by viscous boundary to simulate vibration propagates to infinity.This paper finds that pile-soil coupling affects vibration transmission in the ground.The effect of vertical vibration is greater than horizontal vibration.Either vertical vibration attenuation coefficient or horizontal vibration attenuation coefficient increases with the frequency increases.Finally,the model is applied to the field tests in Shanghai-Hangzhou high-speed railway.This paper finds that the the main frequencies of the vibration induced by the train runs on the viaduct are 3.15,6.3,10,40Hz.(2)This paper uses the substructure method to analyse the vibration characteristics of the viaduct.The entire viaduct-ground vibration system is divided into two sub-structures:the viaduct foundation-soil coupling model and the train-viaduct coupling model.For the vibration response at the ground,this paper superimposes the results obtained for several of its neighboring piers in vibration response at that location.By compared the viaduct field test results in Jiaxing,the result obtained from dynamic substructure method agrees with the result of the field test.This paper finds that the vibration of the span center is higher than span end.The substructure method can simulate the damping effect of vibration damper.(3)This paper applies vertical fatigue load on rubber bearing floating slab with full scale model test equipment.At the same time a series of experiments are done to study the vibration characteristics and damping effect of the slab.Experimental data show that during the fatigue test,the damping effect of the slab changes little.Dynamic stiffness test and acceleration test shows that the natural frequencies of the slab is 14Hz.The vibration damping of the slab mainly through the rubber pad.When the rubber pad remobed,the fastener plays a role in reducing vibration.It is shown that the rubber pad significantly improves the damping effect of the slab.(4)This paper uses the 2.5 dimensional finite element method to analyze the vibration isolation effect of the isolation trench,the isolation wall and the elastic foundation.IS02631 was applied to evaluate how the prarmeters influence the vibration isolation effect.