Mechanism Analysis And Sumulation On Strcutual Vibration And Noise Caused By Urban Subway

With the construction of the urban subway and the expansion of its operation scale, it is convenient for citizens to travel in cities. However, many security issues were brought by urban subway. Vibration and noise are some of these problems which attracted more and more attention from department of metro design, construction and operation. According to the investigations about vibration and noise caused by urban subway, this paper studies the mechanism for generation of noise, propagation characteristics, and its detriment. The vibration of surface structure that generated by running metro was calculated by simulation method. And the radiated noise generated by surface structure vibration was also analyzed. The reliability of numerical simulation results was evaluated by comparing to measurement data. The research results are followed in detail:(1) Referring to references for metro vibration and noise evaluation standard available, this research investigates the mechanism for generation of noise and the regulation for propagation of vibration wave in soil scientifically, and summaries the vibration and noise reduction method in metro engineering.(2)This paper divides the whole system into two subsystems:wheel-rail coupling system and tunnel-soil-structure system. The wheel-rail coupling system was simplified as double bogie vehicle model, Euler beam, continuously discrete elastic supporting model. On the other hand, the tunnel-soil-structure system was simplified as monolithic roadbed, tunnel, layered soil, and frame structure.(3) In order to obtained the wheel-rail force and track force of metro, the vehicle vibration equation and track vibration equation and Newmark implicit integration algorithm were applied to vehicle-track coupling equation which considering the track irregularity. On the basis of tunnel-soil-structure model, relevant chapter calculate the vertical vibration acceleration for each floor and vertical vibration level.(4)In relevant part, wheel-rail force, structure vertical vibration level, and structural noise were calculated with different fastener stiffness. And the influence to environment vibration noise was investigated. It is efficient to control surface structure vibration and structural noise by reducing fastener stiffness. The calculation results show that the higher of building, the higher level of the vertical vibration and the more heavy of secondary structure noise.(5) By comparing the simulation results and measurement data, the reliability of numerical model was evaluated scientifically. There are differences between simulation results and measurement data. Some reasons were given:the high frequency and low frequency impact force that the wheel acting on rail were overestimated in double bogie vehicle model, the stiffness and damping value may be inappropriate during the simplification of track and support structure under track, the method to divide whole system into two sub system may also be inappropriate. It is hard for the layered soil model to simulate propagation of vibration wave accurately. In the surface structure, the building model ignored the pile-supported structures and accessory structure.