Research On Influence Of Vibration Propagation By Common Monolithic Track Bed Type In Urban Rail Transit Tunnel

At present,urban rail transit is developing towards high speed,high density,large axle load and large traffic volume.The impact of wheel rail on track structure is more and more serious.Some diseases of metro track structure are inevitable,such as excessive vibration of ballastless track in specific section,deterioration of wheel rail relationship caused by wear of rail and wheel tread,and damage of vehicle and track components-The vibration of track tunnel has become one of the most important problems concerned by scholars.The structure of the tunnel itself has a significant impact on the vibration of the track and tunnel system under the train load.This dissertation mainly studies the influence of the difference of the design position of the tunnel drainage ditch on the vibration response of the vehicle track tunnel system,so as to provide engineering practice experience for alleviating the tunnel vibration and reducing the damage of the track components.Based on the finite element dynamic theory,the static,modal and dynamic responses of the tunnel are calculated by using the finite element analysis method.The research results show that the track slab,invert center,lining,side wall,vault and ground of the tunnel structure of the double side ditch The vibration acceleration of the tunnel is reduced by 14.7%,1.67%,8.81%,12.27%,8.72% and 1.39% respectively,which indicates that the vibration stability of the central ditch tunnel structure is better,and the vibration attenuation ability is better.Secondly,the vehicle track tunnel simulation model is established by using the co simulation of finite element and multi-body dynamics,and the dynamic characteristics of the train passing through the double side ditch tunnel and the central ditch tunnel are calculated.The acceleration and displacement of different vibration pick-up points of the tunnel structure are analyzed,and the acceleration is processed by frequency spectrum.Finally,the effect of different damping fasteners on reducing the vibration transmission of the tunnel is analyzed The recurrence characteristics are studied.The results show that the two-sided ditch has a certain damping effect,and it has a significant effect on reducing the vibration of the tunnel structure,and the vibration response of the two-sided ditch tunnel is smaller than that of the central ditch tunnel under the same damping fastener.Then,based on the vehicle track tunnel soil coupling dynamic interaction theory,a coupling dynamic model considering different types of track bed is established,and the dynamic behavior and vibration reduction performance of common track bed and composite track bed with different drainage ditch structures under train load are compared and analyzed.Compared with the common monolithic track bed,the vibration acceleration of the rail,track bed and tunnel wall of the composite track bed is significantly reduced,and the acceleration is reduced by 34.48%,48.7% and 38.3% respectively.Compared with the central ditch,the stability of the bilateral ditch is better,which is conducive to the composite track bed to play a good damping effect.The double side ditch tunnel structure not only meets the strength and stability,but also has a certain vibration reduction effect,which perfectly meets the requirements of urban rail transit for vibration reduction and noise reduction,and becomes the underground tunnel structure design of composite practical engineering.